View source for Teratoma

{{Short description|Type of germ cell tumor}}
{{Infobox medical condition
| name = Teratoma
| image = Mature cystic teratoma of ovary.jpg
| caption = A small (4 cm) [[dermoid cyst]] of an ovary, discovered during [[cesarean section]]
| field = [[Gynecology]], [[oncology]]
| symptoms = Minimal, painless lump<ref name=Raj2007/><ref name=NORD2007/>
| complications = [[Ovarian torsion]], [[testicular torsion]], [[hydrops fetalis]]<ref name=Raj2007/><ref name=NORD2007/><ref name=Sab2014/>
| onset = 
| duration = 
| types = Mature, immature<ref name=NCI2017/>
| causes = Unknown<ref name=NORD2007/>
| risks = 
| diagnosis = [[Tissue biopsy]]<ref name=NORD2007/>
| differential = [[Lipoma]], [[dermoid]], [[myelomeningocele]]<ref name=Dav2012/>
| prevention = 
| treatment = Surgery, [[chemotherapy]]<ref name=Dav2012/><ref name=Pri2008/>
| medication = 
| prognosis = 
| frequency = 1 in 30,000 newborns ([[coccyx]])<ref name=Cor2014/>
| deaths = 
}}
<!-- Definition and symptoms -->

A '''teratoma''' is a [[neoplasia|tumor]] made up of several types of [[biological tissue|tissue]], such as [[hair]], [[muscle]], [[Human tooth|teeth]], or [[bone]].<ref name=NCI2017>{{cite web|title=NCI Dictionary of Cancer Terms|url=https://www.cancer.gov/publications/dictionaries/cancer-terms?cdrid=44248|website=National Cancer Institute|access-date=20 December 2017|date = 2011-02-02}}</ref> Teratomata typically form in the [[tailbone]] (where it is known as a [[sacrococcygeal teratoma]]), [[ovary]], or [[testicle]].<ref name="NCI2017" /> 
{{TOC limit|3}}

==Symptoms==
Symptoms may be minimal if the tumor is small.<ref name="NORD2007" /> A testicular teratoma may present as a painless lump.<ref name="Raj2007" /> Complications may include [[ovarian torsion]], [[testicular torsion]], or [[hydrops fetalis]].<ref name="Raj2007">{{cite book| vauthors = Raja SG |title=Access to Surgery: 500 single best answer questions in general and systematic pathology|date=2007|publisher=PasTest Ltd|isbn=978-1-905635-36-8|page=508|url=https://books.google.com/books?id=p2VzWJBpHDAC&pg=PA508|language=en}}</ref><ref name="NORD2007" /><ref name="Sab2014">{{cite book | vauthors = Millet I, Perrochia H, Pages-Bouic E, Curros-Doyon F, Rathat G, Taourel P | chapter = CT and MR of Benign Ovarian Germ Cell Tumours | veditors = Saba L, Acharya UR, Guerriero S, Suri JS |title=Ovarian Neoplasm Imaging|date=2014|publisher=Springer Science & Business Media|isbn=978-1-4614-8633-6 |page=165 | chapter-url=https://books.google.com/books?id=AjLBBAAAQBAJ&pg=PA165|language=en}}</ref>

===Cause and diagnosis===
They are a type of [[germ cell tumor]] (a tumor that begins in the cells that give rise to [[sperm]] or [[egg cell|eggs]]).<ref name=NCI2017/><ref name=NCI2017Mat>{{cite web |title=Mature teratoma |url=https://www.cancer.gov/publications/dictionaries/cancer-terms?cdrid=443575 |website=National Cancer Institute |access-date=20 December 2017 |date = 2011-02-02}}</ref> They are divided into two types: mature and immature.<ref name=NCI2017/> Mature teratomas include [[dermoid cyst]]s and are generally [[benign tumor|benign]].<ref name=NCI2017Mat/> Immature teratomas may be [[cancer]]ous.<ref name=NCI2017/><ref>{{cite book |veditors=Noor MR, Hseon TE, Jeffrey LJ |chapter=Ovarian Germ Cell Tumors |title=Gynaecologic Cancer: A Handbook for Students and Practitioners |date=2014 |publisher=CRC Press |isbn=978-981-4463-06-5 |page=446 |chapter-url=https://books.google.com/books?id=5-bMAwAAQBAJ&pg=PA446 |language=en}}</ref> Most ovarian teratomas are mature.<ref name=Fal2007>{{cite book |vauthors=Falcone T, Hurd WW |title=Clinical Reproductive Medicine and Surgery |date=2007 |publisher=Elsevier Health Sciences |isbn=978-0-323-03309-1 |page=749 |url=https://books.google.com/books?id=fOPtaEIKvcIC&pg=PA749 |language=en}}</ref> In adults, testicular teratomas are generally cancerous.<ref>{{cite book |vauthors=Oyasu R, Yang XJ, Yoshida O |title=Questions in Daily Urologic Practice: Updates for Urologists and Diagnostic Pathologists |date=2009 |publisher=Springer Science & Business Media |isbn=978-4-431-72819-1 |page=253 |url=https://books.google.com/books?id=mD5iUSqheb8C&pg=PA253 |language=en}}</ref> Definitive diagnosis is based on a [[tissue biopsy]].<ref name=NORD2007>{{cite web |title=Sacrococcygeal Teratoma |url=https://rarediseases.org/rare-diseases/sacrococcygeal-teratoma/ |website=NORD (National Organization for Rare Disorders) |access-date=20 December 2017 |date=2007}}</ref>

===Treatment===
Treatment of coccyx, testicular, and ovarian teratomas is generally by surgery.<ref name=Dav2012/><ref name=Pri2008>{{cite book |vauthors=Price P, Sikora K, Illidge T |title=Treatment of Cancer |edition=Fifth |date=2008 |publisher=CRC Press |isbn=978-0-340-91221-8 |page=713 |url=https://books.google.com/books?id=KYIYF2MAUP4C&pg=PA713 |language=en}}</ref><ref>{{cite book |vauthors=Hillard PJ, Hillard PA |title=The 5-minute Obstetrics and Gynecology Consult |date=2008 |publisher=Lippincott Williams & Wilkins |isbn=978-0-7817-6942-6 |page=140 |url=https://books.google.com/books?id=fOoFIQOdIhkC&pg=PA140 |language=en}}</ref> Testicular and immature ovarian teratomas are also frequently treated with [[chemotherapy]].<ref name=Pri2008/><ref name=Fal2007/>

===Epidemiology===
Teratomas occur in the coccyx in about one in 30,000 newborns, making them one of the most common tumors in this age group.<ref name=Dav2012/><ref name=Cor2014>{{cite book |vauthors=Corton MM, Leveno KJ, Bloom SL, Hoffman BL |title=Williams Obstetrics 24/E (EBOOK) |date=2014 |publisher=McGraw Hill Professional |isbn=978-0-07-179894-5 |page=Chapter 16 |url=https://books.google.com/books?id=TlPOAgAAQBAJ|language=en}}</ref> Females are affected more often than males.<ref name=Dav2012>{{cite book |vauthors=Davies M, Inglis G, Jardine L, Koorts P |title=Antenatal Consults: A Guide for Neonatologists and Paediatricians - E-Book |date=2012 |publisher=Elsevier Health Sciences |isbn=978-0-7295-8108-0 |page=298 |url=https://books.google.com/books?id=soTU42jrIkUC&pg=PA298 |language=en}}</ref> Ovarian teratomas represent about a quarter of [[ovarian tumor]]s and are typically noticed during middle age.<ref name=Fal2007/> Testicular teratomas represent almost half of [[testicular cancer]]s.<ref>{{cite book |vauthors=Hart I, Newton RW |title=Endocrinology |date=2012 |publisher=Springer Science & Business Media |isbn=978-94-010-9298-2 |page=157 |url=https://books.google.com/books?id=QbjUBgAAQBAJ&pg=PA157 |language=en}}</ref> They can occur in both children and adults.<ref>{{cite book |vauthors=McDougal WS, Wein AJ, Kavoussi LR, Partin AW, Peters CA, Ramchandani P |title=Campbell-Walsh Urology |edition=10th |date=2011 |publisher=Elsevier Health Sciences |isbn=978-1-4557-2317-1 |page=663 |url=https://books.google.com/books?id=tKcS1A2Q9dAC&pg=PA663 |language=en}}</ref> The term comes from the Greek word for [[Teratology|"monster"]]<ref>{{cite book |vauthors=Chang AE, Ganz PA, Hayes DF, Kinsella T, Pass HI, Schiller JH, Stone RM, Strecher V |title=Oncology: An Evidence-Based Approach |date=2007 |publisher=Springer Science & Business Media |isbn=978-0-387-31056-5 |page=848 |url=https://books.google.com/books?id=vxh6u1-ETk0C&pg=PA848 |language=en }}</ref> plus the "-oma" suffix used for tumors.

Teratomas can cause an autoimmune illness called [[Anti-NMDA receptor encephalitis]]. In this condition, the teratomas may contain B cells with NMDA-receptor specificities.<ref>{{cite journal |vauthors=Makuch M, Wilson R, Al-Diwani A, Varley J, Kienzler AK, Taylor J, Berretta A, Fowler D, Lennox B, Leite MI, Waters P, Irani SR |display-authors=6 |title=N-methyl-D-aspartate receptor antibody production from germinal center reactions: Therapeutic implications |journal=Annals of Neurology |volume=83 |issue=3 |pages=553–561 |date=March 2018 |pmid=29406578 |pmc=5925521 |doi=10.1002/ana.25173 }}</ref>

After teratoma removal surgery, a risk exists of regrowth in place, or in nearby organs.<ref>{{cite journal |vauthors=Choi KW, Jeon WJ, Chae HB, Park SM, Youn SJ, Shin HM, Sung RH, Lee SJ |display-authors=6 |title=[A recurred case of a mature ovarian teratoma presenting as a rectal mass] |language=ko |journal=The Korean Journal of Gastroenterology = Taehan Sohwagi Hakhoe Chi |volume=42 |issue=3 |pages=242–245 |date=September 2003 |pmid=14532748 |url=https://pdf.medrang.co.kr/Kjg/042/Kjg042-03-11.pdf }}</ref>

==Types==

===Mature teratoma===<!-- [[Mature teratoma]] redirects here -->
[[File:Ovarian teratoma with hair.jpg|thumb|Ovarian teratoma with hair inside]]
[[File:Mature teratoma, mediastinum.jpg|thumb|Mature teratoma of the mediastinum: A horizontal slice of the resected tumor reveals fibrofatty tissue, calcified areas, and a few cystic spaces lined with smooth membrane and containing a hair. In the left lower corner, the involved B5 bronchus is evident.]]
A mature teratoma is a grade 0 teratoma. They are highly variable in form and histology, and may be solid, cystic, or a combination of the two. A mature teratoma often contains several different types of tissue such as [[Human skin|skin]], [[muscle]], and [[bone]]. Skin may surround a cyst and grow abundant [[hair]] {{crossreference|(see: {{section link||Dermoid cyst}})}}. Mature teratomas generally are benign, with 0.17–2% of mature cystic teratomas becoming malignant.<ref name="MandalBadhe2012">{{cite journal | vauthors = Mandal S, Badhe BA | title = Malignant transformation in a mature teratoma with metastatic deposits in the omentum: a case report | journal = Case Reports in Pathology | volume = 2012 | article-number = 568062 | year = 2012 | pmid = 23082264 | pmc = 3469088 | doi = 10.1155/2012/568062 | doi-access = free }}</ref>

=== Immature teratoma ===
Immature teratoma is the malignant counterpart of the mature teratoma and contains immature tissues which typically show [[Dedifferentiation|primitive or embryonal]] [[neuroectoderm]]al histopathology. Immature teratoma has one of the lowest rates of [[somatic mutation]] of any tumor type and results from one of five mechanisms of [[meiosis|meiotic failure]].<ref name=":0">{{cite journal | vauthors = Heskett MB, Sanborn JZ, Boniface C, Goode B, Chapman J, Garg K, Rabban JT, Zaloudek C, Benz SC, Spellman PT, Solomon DA, Cho RJ | display-authors = 6 | title = Multiregion exome sequencing of ovarian immature teratomas reveals 2N near-diploid genomes, paucity of somatic mutations, and extensive allelic imbalances shared across mature, immature, and disseminated components | journal = Modern Pathology | volume = 33 | issue = 6 | pages = 1193–1206 | date = June 2020 | pmid = 31911616 | pmc = 7286805 | doi = 10.1038/s41379-019-0446-y }}</ref>

=== Gliomatosis peritoneii ===
Gliomatosis peritoneii, which presents as a deposition of mature glial cells in the peritoneum, is almost exclusively seen in conjunction with cases of ovarian teratoma. Through genetic studies of exome sequence, it was found that gliomatosis is genetically identical to the parent ovarian tumor and developed from cells that disseminate from the ovarian teratoma.<ref name=":0" />

=== Dermoid cyst ===
A [[dermoid cyst]] is a mature cystic teratoma containing hair (sometimes very abundant) and other structures characteristic of normal skin and other tissues derived from the [[ectoderm]]. The term is most often applied to teratoma on the [[skull suture]]s and in the ovaries of females.{{citation needed|date=June 2020}}

{{clear left}}

=== Fetus ''in fetu'' and fetiform teratoma===
[[Fetus in fetu|Fetus ''in fetu'']] and fetiform teratoma are rare forms of mature teratomas that include one or more components resembling a malformed fetus. Both forms may contain or appear to contain complete organ systems, even major body parts, such as a torso or limbs. Fetus ''in fetu ''differs from fetiform teratoma in having an apparent [[vertebral column|spine]] and [[bilateral symmetry]].<ref name="Gonzalez-Crussi1982"/>

Most authorities agree that fetiform teratomas are highly developed mature teratomas; the natural history of fetus ''in fetu'' is controversial.<ref name="Gonzalez-Crussi1982"/> It has been noted that fetiform teratoma is reported more often (by gynecologists) in ovarian teratomas, and fetus ''in fetu'' is reported more often (by general surgeons) in retroperitoneal teratomas. Fetus ''in fetu'' has often been interpreted as a [[fetus]] growing within its [[twin]]. As such, this interpretation assumes a special complication of [[twin]]ning, one of several grouped under the term [[parasitic twin]]. In many cases, the fetus ''in fetu'' is reported to occupy a fluid-filled cyst within a mature teratoma.<ref name="pmid6724790">{{cite journal | vauthors = Abbott TM, Hermann WJ, Scully RE | title = Ovarian fetiform teratoma (homunculus) in a 9-year-old girl | journal = International Journal of Gynecological Pathology | volume = 2 | issue = 4 | pages = 392–402 | year = 1984 | pmid = 6724790 | doi = 10.1097/00004347-198404000-00007 }}</ref><ref>{{cite journal | vauthors = Saito K, Katsumata Y, Hirabuki T, Kato K, Yamanaka M | title = Fetus-in-fetu: parasite or neoplasm? A study of two cases | journal = Fetal Diagnosis and Therapy | volume = 22 | issue = 5 | pages = 383–388 | year = 2007 | pmid = 17556829 | doi = 10.1159/000103301 | s2cid = 57099054 }}</ref><ref>{{cite journal | vauthors = Kajbafzadeh AM, Baharnoori M | title = Fetus in fetu | journal = The Canadian Journal of Urology | volume = 13 | issue = 5 | pages = 3277–3278 | date = October 2006 | pmid = 17076951 }}</ref><ref>{{cite journal | vauthors = Chua JH, Chui CH, Sai Prasad TR, Jabcobsen AS, Meenakshi A, Hwang WS | title = Fetus-in-fetu in the pelvis: report of a case and literature review | journal = Annals of the Academy of Medicine, Singapore | volume = 34 | issue = 10 | pages = 646–649 | date = November 2005 | pmid = 16382253 | url = https://www.annals.edu.sg/pdf/34VolNo10200511/V34N10p646.pdf }}</ref> Cysts within mature teratomas may have partially-developed organ systems: reports include cases of partial [[cranial bones]], [[long bones]] and a rudimentary, beating heart.<ref>{{cite journal | vauthors = Lee YH, Kim SG, Choi SH, Kim IS, Kim SH | title = Ovarian mature cystic teratoma containing homunculus: a case report | journal = Journal of Korean Medical Science | volume = 18 | issue = 6 | pages = 905–907 | date = December 2003 | pmid = 14676454 | pmc = 3055135 | doi = 10.3346/jkms.2003.18.6.905 | url = http://jkms.kams.or.kr/2003/pdf/12905.pdf | archive-url = https://web.archive.org/web/20110722140946/http://jkms.kams.or.kr/2003/pdf/12905.pdf | archive-date = 2011-07-22 }}<!-- also available at: http://www.biomedsearch.com/attachments/00/14/67/64/14676454/14676454.pdf and http://jkms.xmlink.kr/Synapse/Data/PDFData/0063JKMS/jkms-18-905.pdf --></ref><ref>{{cite journal | vauthors = Kazez A, Ozercan IH, Erol FS, Faik Ozveren M, Parmaksiz E | title = Sacrococcygeal heart: a very rare differentiation in teratoma | journal = European Journal of Pediatric Surgery | volume = 12 | issue = 4 | pages = 278–280 | date = August 2002 | pmid = 12369008 | doi = 10.1055/s-2002-34483 | s2cid = 260136953 }}</ref>

Regardless of whether fetus ''in fetu'' and fetiform teratoma are one entity or two, they are distinct from and not to be confused with [[ectopic pregnancy]].

=== ''Struma ovarii'' ===
{{main|Struma ovarii}}
A ''struma ovarii'' (also known as [[goitre]] of the ovary or ovarian goiter) is a rare form of mature teratoma that contains mostly [[thyroid]] tissue.<ref>{{cite journal |vauthors = Frysak Z, Schovanek J, Halenka M, Metelkova I, Duskova M, Karasek D |title = Ovarian Goiter as a Rare Cause of Hyperthyroidism |journal = Acta Endocrinologica |volume = 12 |issue = 3 |pages = 335–338 |date = 2016 |pmid = 31149110 |pmc = 6535264 |doi = 10.4183/aeb.2016.335 }}</ref>

=== Epignathus ===
{{main|Epignathus}}

Epignathus is a rare teratoma originating in the oropharyngeal area that occurs ''in utero''. It presents with a mass protruding from the mouth at birth. Untreated, breathing is impossible. An [[EXIT procedure]] is the recommended initial treatment.

==Fetal teratomas==
Teratomas may be found in babies, children, and adults. Teratomas of embryonal origin are most often found in babies at birth, in young children, and, since the advent of [[Medical ultrasonography|ultrasound imaging]], in fetuses.

The most diagnosed fetal teratomas are [[sacrococcygeal teratoma]] (Altman types I, II, and III) and cervical (neck) teratoma. Because these teratomas project from the fetal body into the surrounding [[Amniotic sac|amniotic fluid]], they can be seen during routine prenatal ultrasound exams. Teratomas within the fetal body are less easily seen with ultrasound; for these, MRI of the pregnant uterus is more informative.<ref>{{cite journal | vauthors = Danzer E, Hubbard AM, Hedrick HL, Johnson MP, Wilson RD, Howell LJ, Flake AW, Adzick NS | display-authors = 6 | title = Diagnosis and characterization of fetal sacrococcygeal teratoma with prenatal MRI | journal = AJR. American Journal of Roentgenology | volume = 187 | issue = 4 | pages = W350–W356 | date = October 2006 | pmid = 16985105 | doi = 10.2214/AJR.05.0152 }}</ref><ref>{{cite journal | vauthors = Kocaoglu M, Frush DP | title = Pediatric presacral masses | journal = Radiographics | volume = 26 | issue = 3 | pages = 833–857 | year = 2006 | pmid = 16702458 | doi = 10.1148/rg.263055102 }}</ref>

===Complications===
Teratomas are not dangerous for the fetus unless either a [[mass effect (medicine)|mass effect]] occurs or a large amount of blood flows through the tumor (known as vascular steal). The mass effect frequently consists of obstruction of normal passage of fluids from surrounding organs. The vascular steal can place a strain on the growing heart of the fetus, even resulting in heart failure, thus must be monitored by fetal [[echocardiography]].

==Pathophysiology==
{{main|Germ cell tumor}}
Teratomas belong to a class of tumors known as [[nonseminoma]]tous [[germ cell tumor]]. All tumors of this class are the result of abnormal development of [[pluripotent]] cells: [[germ cell]]s and [[embryo|embryonal cells]]. Teratomas of embryonic origin are [[congenital disorder|congenital]]; teratomas of germ cell origin may or may not be congenital. The kind of pluripotent cell appears to be unimportant, apart from constraining the location of the teratoma in the body.

Teratomas derived from germ cells occur in the [[testicle]] and [[ovary|ovaries]]. Teratomas derived from embryonic cells usually occur on the subject's midline: in the brain, elsewhere in the [[Human skull|skull]], in the nose, in the tongue, under the tongue, and in the [[neck]] (cervical teratoma), [[mediastinum]], [[retroperitoneum]], and attached to the [[coccyx]]. Teratomas may also occur elsewhere: very rarely in solid organs (most notably the heart and liver) and hollow organs (such as the stomach and bladder), and more commonly on the [[cranial sutures|skull sutures]].

Teratoma rarely include more complicated body parts such as [[Human tooth|teeth]], [[Human brain|brain matter]],<ref>{{cite journal | vauthors = Shintaku M, Sakuma T, Ohbayashi C, Maruo M | title = Well-formed cerebellum and brainstem-like structures in a mature ovarian teratoma: Neuropathological observations | language = en-US | journal = Neuropathology | volume = 37 | issue = 2 | pages = 122–128 | date = April 2017 | pmid = 28042664 | doi = 10.1111/neup.12360 | s2cid = 25588284 }}</ref> [[Human eye|eyes]],<ref name="pmid6540049">{{cite journal | vauthors = Chi JG, Lee YS, Park YS, Chang KY | title = Fetus-in-fetu: report of a case | journal = American Journal of Clinical Pathology | volume = 82 | issue = 1 | pages = 115–119 | date = July 1984 | pmid = 6540049 | doi = 10.1093/ajcp/82.1.115 }}</ref><ref name="pmid9841706">{{cite journal | vauthors = Sergi C, Ehemann V, Beedgen B, Linderkamp O, Otto HF | title = Huge fetal sacrococcygeal teratoma with a completely formed eye and intratumoral DNA ploidy heterogeneity | journal = Pediatric and Developmental Pathology | volume = 2 | issue = 1 | pages = 50–57 | year = 1999 | pmid = 9841706 | doi = 10.1007/s100249900089 | s2cid = 22847474 }}</ref> or [[torso]].<ref name="pmid19184054">{{cite journal | vauthors = Arlikar JD, Mane SB, Dhende NP, Sanghavi Y, Valand AG, Butale PR | title = Fetus in fetu: two case reports and review of literature | journal = Pediatric Surgery International | volume = 25 | issue = 3 | pages = 289–292 | date = March 2009 | pmid = 19184054 | doi = 10.1007/s00383-009-2328-8 | s2cid = 11210782 }}</ref>

===Hypotheses of origin===
Concerning the origin of teratomas, numerous hypotheses exist.<ref name="Gonzalez-Crussi1982">Gonzalez-Crussi F (1982) Extragonadal Teratomas. Atlas of Tumor Pathology, Second Series, Fascicle 18. [[Armed Forces Institute of Pathology]], Washington D.C.</ref> These hypotheses are not to be confused with the unrelated hypothesis that fetus ''in fetu'' (see below) is not a teratoma at all, but rather a [[parasitic twin]].

==Diagnosis==
[[File:Teratom 001-03.png|thumb|CT showing a teratoma of the ovary: fatty formation with a smooth boundary, with a dense part, possibly a tooth.]]
[[File:Teratoma 2 low mag.jpg|thumb|[[Micrograph]] of a teratoma showing tissue from all three [[germ layer]]s: [[mesoderm]] (immature [[cartilage]] - left-upper), [[endoderm]] (gastrointestinal glands - center-bottom) and [[ectoderm]] (epidermis - right)]]
Teratomas are thought to originate ''in utero'', so can be considered [[congenital]] tumors. Many teratomas are not diagnosed until much later in childhood or in adulthood. Large tumors are more likely to be diagnosed early on. Sacrococcygeal and cervical teratomas are often detected by prenatal [[ultrasound]]. Additional diagnostic methods may include prenatal [[magnetic resonance imaging]]. In rare circumstances, the tumor is so large that the fetus may be damaged or die. In the case of large sacrococcygeal teratomas, a significant portion of the fetus' [[blood flow]] is redirected toward the teratoma (a phenomenon called [[Cardiac steal syndrome|steal syndrome]]), causing [[Congestive heart failure|heart failure]], or [[hydrops fetalis|hydrops]], of the fetus. In certain cases, [[fetal surgery]] may be indicated.

Beyond the newborn period, symptoms of a teratoma depend on its location and organ of origin. Ovarian teratomas often present with abdominal or [[Chronic pelvic pain|pelvic pain]], caused by [[Torsion (mechanics)|torsion]] of the ovary or irritation of its ligaments. A recently discovered condition where ovarian teratomas cause encephalitis associated with antibodies against the [[N-methyl-D-aspartate]] receptor antibody (NMDAR) - often referred to as "[[anti-NMDA receptor encephalitis]]", was identified as a serious complication. Patients develop a multistage illness that progresses from psychosis, memory deficits, seizures, and language disintegration into a state of unresponsiveness with catatonic features often associated with abnormal movements, and autonomic and breathing instability.<ref>{{cite journal | vauthors = Dalmau J, Lancaster E, Martinez-Hernandez E, Rosenfeld MR, Balice-Gordon R | title = Clinical experience and laboratory investigations in patients with anti-NMDAR encephalitis | journal = The Lancet. Neurology | volume = 10 | issue = 1 | pages = 63–74 | date = January 2011 | pmid = 21163445 | pmc = 3158385 | doi = 10.1016/S1474-4422(10)70253-2 }}</ref> Testicular teratomas present as a palpable mass in the testis; [[mediastinum|mediastinal]] teratomas often cause compression of the lungs or the airways and may present with [[chest pain]] and/or respiratory symptoms.

Some teratomas contain [[yolk sac]] elements, which secrete [[alpha-fetoprotein]]. Its detection may help to confirm the diagnosis and is often used as a marker for recurrence or treatment efficacy, but is rarely the method of initial diagnosis. (Maternal serum [[alpha-fetoprotein]] is a useful [[Screening (medicine)|screening test]] for other fetal conditions, including [[Down syndrome]], [[spina bifida]], and [[Layers of the abdominal wall|abdominal wall]] defects such as [[gastroschisis]].)

===Classification===
Regardless of location in the body, a teratoma is classified according to a [[cancer staging]] system. This indicates whether [[chemotherapy]] or [[radiation therapy]] may be needed in addition to surgery. Teratomas commonly are classified using the [[F. Gonzalez-Crussi|Gonzalez-Crussi]]<ref name="Gonzalez-Crussi1982"/> grading system: 0 or mature ([[benign]]); 1 or immature, probably benign; 2 or immature, possibly [[malignant]] (cancerous); and 3 or frankly malignant. If frankly malignant, the tumor is a cancer for which additional cancer staging applies.{{citation needed|date=June 2020}}

Teratomas are also classified by their content; a solid teratoma contains only tissues (perhaps including more complex structures); a cystic teratoma contains only pockets of fluid or semifluid such as [[cerebrospinal fluid]], [[sebum]], or fat; a mixed teratoma contains both solid and cystic parts. Cystic teratomas usually are grade 0 and, conversely, grade 0 teratomas usually are cystic.

Grades 0, 1, and 2 pure teratomas have the potential to become malignant (grade 3), and malignant pure teratomas have the potential to [[metastasize]]. These rare forms of teratoma with malignant transformation may contain elements of somatic (not germ cell) malignancy such as [[leukemia]], [[carcinoma]], or [[sarcoma]].<ref name="pmid17080330">{{cite journal | vauthors = Harms D, Zahn S, Göbel U, Schneider DT | title = Pathology and molecular biology of teratomas in childhood and adolescence | journal = Klinische Padiatrie | volume = 218 | issue = 6 | pages = 296–302 | year = 2006 | pmid = 17080330 | doi = 10.1055/s-2006-942271 | s2cid = 20627932 }}</ref>
A teratoma may contain elements of other germ cell tumors, in which case it is not a pure teratoma, but rather is a mixed [[germ cell tumor]] and is malignant. In infants and young children, these elements usually are [[endodermal sinus tumor]], followed by [[choriocarcinoma]]. Finally, a teratoma can be pure and not malignant yet highly aggressive; this is exemplified by [[growing teratoma syndrome]], in which chemotherapy eliminates the malignant elements of a mixed tumor, leaving pure teratoma, which paradoxically begins to grow very rapidly.<ref>{{cite journal | vauthors = Scavuzzo A, Santana Ríos ZA, Noverón NR, Jimenez Ríos MA | title = Growing teratoma syndrome | journal = Case Reports in Urology | volume = 2014 | article-number = 139425 | date = 2014 | pmid = 25197607 | pmc = 4150507 | doi = 10.1155/2014/139425 | doi-access = free }}</ref>

==== Malignant transformation====
A "benign" grade 0 (mature) teratoma nonetheless has a risk of malignancy. Recurrence with malignant [[endodermal sinus tumor]] has been reported in cases of formerly benign mature teratoma,<ref name="pmid9781660">{{cite journal | vauthors = Ohno Y, Kanematsu T | title = An endodermal sinus tumor arising from a mature cystic teratoma in the retroperitoneum in a child: is a mature teratoma a premalignant condition? | journal = Human Pathology | volume = 29 | issue = 10 | pages = 1167–1169 | date = October 1998 | pmid = 9781660 | doi = 10.1016/S0046-8177(98)90432-4 }}</ref><ref name="pmid17564180">{{cite journal | vauthors = Utsuki S, Oka H, Sagiuchi T, Shimizu S, Suzuki S, Fujii K | title = Malignant transformation of intracranial mature teratoma to yolk sac tumor after late relapse. Case report | journal = Journal of Neurosurgery | volume = 106 | issue = 6 | pages = 1067–1069 | date = June 2007 | pmid = 17564180 | doi = 10.3171/jns.2007.106.6.1067 | s2cid = 23864999 }}</ref> even in fetiform teratoma and fetus in fetu.<ref name="pmid17561476">{{cite journal | vauthors = Chen YH, Chang CH, Chen KC, Diau GY, Loh IW, Chu CC | title = Malignant transformation of a well-organized sacrococcygeal fetiform teratoma in a newborn male | journal = Journal of the Formosan Medical Association = Taiwan Yi Zhi | volume = 106 | issue = 5 | pages = 400–402 | date = May 2007 | pmid = 17561476 | doi = 10.1016/S0929-6646(09)60326-0 | doi-access = }}{{Dead link|date=June 2018 |bot=InternetArchiveBot |fix-attempted=no }}</ref><ref name="pmid9349774">{{cite journal | vauthors = Hopkins KL, Dickson PK, Ball TI, Ricketts RR, O'Shea PA, Abramowsky CR | title = Fetus-in-fetu with malignant recurrence | journal = Journal of Pediatric Surgery | volume = 32 | issue = 10 | pages = 1476–1479 | date = October 1997 | pmid = 9349774 | doi = 10.1016/S0022-3468(97)90567-4 }}</ref> [[Squamous cell carcinoma]] has been found in a mature cystic teratoma at the time of initial surgery.<ref name="pmid18592797">{{cite journal | vauthors = Arioz DT, Tokyol C, Sahin FK, Koker G, Yilmaz S, Yilmazer M, Ozalp S | title = Squamous cell carcinoma arising in a mature cystic teratoma of the ovary in young patient with elevated carbohydrate antigen 19-9 | journal = European Journal of Gynaecological Oncology | volume = 29 | issue = 3 | pages = 282–284 | year = 2008 | pmid = 18592797 }}</ref> A grade 1 immature teratoma that appears to be benign (e.g., because AFP is not elevated) has a much higher risk of malignancy, and requires adequate follow-up.<ref name="pmid15895292">{{cite journal | vauthors = Muscatello L, Giudice M, Feltri M | title = Malignant cervical teratoma: report of a case in a newborn | journal = European Archives of Oto-Rhino-Laryngology | volume = 262 | issue = 11 | pages = 899–904 | date = November 2005 | pmid = 15895292 | doi = 10.1007/s00405-005-0917-2 | s2cid = 11556991 }}</ref><ref name="pmid15928937">{{cite journal | vauthors = Ukiyama E, Endo M, Yoshida F, Tezuka T, Kudo K, Sato S, Akatsuka S, Hata J | display-authors = 6 | title = Recurrent yolk sac tumor following resection of a neonatal immature gastric teratoma | journal = Pediatric Surgery International | volume = 21 | issue = 7 | pages = 585–588 | date = July 2005 | pmid = 15928937 | doi = 10.1007/s00383-005-1404-y | s2cid = 40147917 }}</ref><ref name="pmid7508500">{{cite journal | vauthors = Bilik R, Shandling B, Pope M, Thorner P, Weitzman S, Ein SH | title = Malignant benign neonatal sacrococcygeal teratoma | journal = Journal of Pediatric Surgery | volume = 28 | issue = 9 | pages = 1158–1160 | date = September 1993 | pmid = 7508500 | doi = 10.1016/0022-3468(93)90154-D }}</ref><ref name="pmid7692755">{{cite journal | vauthors = Hawkins E, Issacs H, Cushing B, Rogers P | title = Occult malignancy in neonatal sacrococcygeal teratomas. A report from a Combined Pediatric Oncology Group and Children's Cancer Group study | journal = The American Journal of Pediatric Hematology/Oncology | volume = 15 | issue = 4 | pages = 406–409 | date = November 1993 | pmid = 7692755 }}</ref>
This grade of teratoma also may be difficult to diagnose correctly. It can be confused with other small round cell neoplasms such as neuroblastoma, small cell carcinoma of hypercalcemic type, primitive neuroectodermal tumor, Wilm's tumor, desmoplastic small round cell tumor, and non-Hodgkin [[lymphoma]].<ref name="pmid18618728">{{cite journal | vauthors = Ramalingam P, Teague D, Reid-Nicholson M | title = Imprint cytology of high-grade immature ovarian teratoma: a case report, literature review, and distinction from other ovarian small round cell tumors | journal = Diagnostic Cytopathology | volume = 36 | issue = 8 | pages = 595–599 | date = August 2008 | pmid = 18618728 | doi = 10.1002/dc.20849 | s2cid = 21066080 }}</ref>

A teratoma with malignant transformation (TMT) is a very rare form of teratoma that may contain elements of somatic malignant tumors such as leukemia, carcinoma, or sarcoma.<ref name="pmid17080330"/> Of 641 children with pure teratoma, nine developed TMT:<ref>{{cite journal | vauthors = Biskup W, Calaminus G, Schneider DT, Leuschner I, Göbel U | title = Teratoma with malignant transformation: experiences of the cooperative GPOH protocols MAKEI 83/86/89/96 | journal = Klinische Padiatrie | volume = 218 | issue = 6 | pages = 303–308 | year = 2006 | pmid = 17080331 | doi = 10.1055/s-2006-942272 | s2cid = 260569521 }}</ref> five carcinoma, two [[glioma]], and two embryonal carcinoma (here, these last are classified among germ cell tumors).

In November 2024, the SCT-study consortium published the risk of malignancy at initial resection in sacrococcygeal teratoma increases with age reaching a plateau at 6 years of age.<ref>{{Cite journal |last=van Heurn |first=Lieke J. |last2=Derikx |first2=Joep P. M. |last3=Hall |first3=Nigel |last4=Aldrink |first4=Jennifer H. |last5=Bailez |first5=Maria M. |last6=Chirdan |first6=Lohfa B. |last7=Fumino |first7=Shigehisa |last8=Hesse |first8=Afua |last9=Soyer |first9=Tuktu |last10=StPeter |first10=Shawn |last11=Twisk |first11=Jos |last12=Yang |first12=Tianyou |last13=van Heurn |first13=Ernst L. W. |last14=Consortium |first14=The SCT-study |last15=Elfiky |first15=Mahmoud |title=Malignant transformation and tumour recurrence in sacrococcygeal teratoma: a global, retrospective cohort study |url=https://journals.lww.com/international-journal-of-surgery/fulltext/2024/11000/malignant_transformation_and_tumour_recurrence_in.35.aspx |journal=International Journal of Surgery |language=en-US |volume=110 |issue=11 |page=7177 |doi=10.1097/JS9.0000000000002045|pmc=11573091 }}</ref>

==== Extraspinal ependymoma ====
Extraspinal [[ependymoma]], usually considered to be a glioma (a type of nongerm cell tumor), may be an unusual form of mature teratoma.<ref>{{cite journal | vauthors = Aktuğ T, Hakgüder G, Sarioğlu S, Akgür FM, Olguner M, Pabuçcuoğlu U | title = Sacrococcygeal extraspinal ependymomas: the role of coccygectomy | journal = Journal of Pediatric Surgery | volume = 35 | issue = 3 | pages = 515–518 | date = March 2000 | pmid = 10726703 | doi = 10.1016/S0022-3468(00)90228-8 }}</ref>

==Treatment==

===Surgery===
The treatment of choice is complete surgical removal (''i.e.,'' complete resection).<ref>{{cite journal | vauthors = Tapper D, Lack EE | title = Teratomas in infancy and childhood. A 54-year experience at the Children's Hospital Medical Center | journal = Annals of Surgery | volume = 198 | issue = 3 | pages = 398–410 | date = September 1983 | pmid = 6684416 | pmc = 1353316 | doi = 10.1097/00000658-198309000-00016 }}</ref><ref>{{cite journal | vauthors = Göbel U, Schneider DT, Calaminus G, Haas RJ, Schmidt P, Harms D | title = Germ-cell tumors in childhood and adolescence. GPOH MAKEI and the MAHO study groups | journal = Annals of Oncology | volume = 11 | issue = 3 | pages = 263–271 | date = March 2000 | pmid = 10811491 | doi = 10.1023/a:1008360523160 | doi-access = free }}</ref> Teratomas are normally well-encapsulated and noninvasive of surrounding tissues, hence they are relatively easy to resect from surrounding tissues. Exceptions include teratomas in the brain, and very large, complex teratomas that have pushed into and become interlaced with adjacent muscles and other structures.

Prevention of recurrence does not require ''en bloc'' resection of surrounding tissues.

===Chemotherapy===
For malignant teratomas, usually, surgery is followed by chemotherapy.

Teratomas that are in surgically inaccessible locations, or are very complex, or are likely to be malignant (due to late discovery and/or treatment) sometimes are treated first with chemotherapy. {{citation needed |date=February 2016}}

===Follow-up===
Although often described as benign, a teratoma does have malignant potential. A UK study of 351 infants and children diagnosed with "benign" teratoma reported 227 with mature teratoma, 124 with immature teratoma. Five years after surgery, event-free survival was 92.2% and 85.9%, respectively, and overall survival was 99% and 95.1%.<ref name="pmid18541896">{{cite journal | vauthors = Mann JR, Gray ES, Thornton C, Raafat F, Robinson K, Collins GS, Gornall P, Huddart SN, Hale JP, Oakhill A | display-authors = 6 | title = Mature and immature extracranial teratomas in children: the UK Children's Cancer Study Group Experience | journal = Journal of Clinical Oncology | volume = 26 | issue = 21 | pages = 3590–3597 | date = July 2008 | pmid = 18541896 | doi = 10.1200/JCO.2008.16.0622 | doi-access = free }}</ref> A similar study in Italy reported on 183 infants and children diagnosed with teratoma. At 10 years after surgery, event-free and overall survival were 90.4% and 98%, respectively.<ref name="pmid17333214">{{cite journal | vauthors = Lo Curto M, D'Angelo P, Cecchetto G, Klersy C, Dall'Igna P, Federico A, Siracusa F, Alaggio R, Bernini G, Conte M, De Laurentis T, Di Cataldo A, Inserra A, Santoro N, Tamaro P, Indolfi P | display-authors = 6 | title = Mature and immature teratomas: results of the first paediatric Italian study | journal = Pediatric Surgery International | volume = 23 | issue = 4 | pages = 315–322 | date = April 2007 | pmid = 17333214 | doi = 10.1007/s00383-007-1890-1 | s2cid = 1380993 }}</ref>

Depending on which tissue(s) it contains, a teratoma may secrete a variety of chemicals with systemic effects. Some teratomas secrete the "pregnancy hormone" [[human chorionic gonadotropin]] (βhCG), which can be used in clinical practice to monitor the successful treatment or relapse in patients with a known HCG-secreting teratoma. This hormone is not recommended as a diagnostic marker, because most teratomas do not secrete it. Some teratomas secrete [[thyroxine]], in some cases to such a degree that it can lead to clinical [[hyperthyroidism]] in the patient. Of special concern is the secretion of [[alpha-fetoprotein]] (AFP); under some circumstances, AFP can be used as a diagnostic marker specific for the presence of [[yolk sac]] cells within the teratoma. These cells can develop into a frankly malignant tumor known as [[yolk sac tumor]] or [[endodermal sinus tumor]].

Adequate follow-up requires close observation, involving repeated physical examination, scanning (ultrasound, MRI, or CT), and measurement of AFP and/or βhCG.<ref name="pmid10561269">{{cite journal | vauthors = Marina NM, Cushing B, Giller R, Cohen L, Lauer SJ, Ablin A, Weetman R, Cullen J, Rogers P, Vinocur C, Stolar C, Rescorla F, Hawkins E, Heifetz S, Rao PV, Krailo M, Castleberry RP | display-authors = 6 | title = Complete surgical excision is effective treatment for children with immature teratomas with or without malignant elements: A Pediatric Oncology Group/Children's Cancer Group Intergroup Study | journal = Journal of Clinical Oncology | volume = 17 | issue = 7 | pages = 2137–2143 | date = July 1999 | pmid = 10561269 | doi = 10.1200/JCO.1999.17.7.2137 }}</ref><ref name="pmid10454682">{{cite journal | vauthors = Cushing B, Giller R, Ablin A, Cohen L, Cullen J, Hawkins E, Heifetz SA, Krailo M, Lauer SJ, Marina N, Rao PV, Rescorla F, Vinocur CD, Weetman RM, Castleberry RP | display-authors = 6 | title = Surgical resection alone is effective treatment for ovarian immature teratoma in children and adolescents: a report of the pediatric oncology group and the children's cancer group | journal = American Journal of Obstetrics and Gynecology | volume = 181 | issue = 2 | pages = 353–358 | date = August 1999 | pmid = 10454682 | doi = 10.1016/S0002-9378(99)70561-2 }}</ref>

==Epidemiology==
[[File:Ovarian tumors by incidence and cancer risk.png|thumb|320px|[[Ovarian tumor]]s by [[Incidence (epidemiology)|incidence]] and risk of [[ovarian cancer]], with mature cystic teratoma at bottom and [[immature teratoma]] at right.<ref>- {{cite journal| vauthors = Vaidya S, Sharma P, KC S, Vaidya SA |title=Spectrum of ovarian tumors in a referral hospital in Nepal|journal=Journal of Pathology of Nepal|volume=4|issue=7|year=2014|pages=539–543|issn=2091-0908|doi=10.3126/jpn.v4i7.10295|doi-access=free}}<br />- Minor adjustment for mature cystic teratomas (0.17 to 2% risk of ovarian cancer): {{cite journal | vauthors = Mandal S, Badhe BA | title = Malignant transformation in a mature teratoma with metastatic deposits in the omentum: a case report | journal = Case Reports in Pathology | volume = 2012 | article-number = 568062 | year = 2012 | pmid = 23082264 | pmc = 3469088 | doi = 10.1155/2012/568062 | doi-access = free }}</ref>]]
Embryonal teratomas most commonly occur in the sacrococcygeal region; [[sacrococcygeal teratoma]] is the single most common tumor found in newborn humans.

Of teratomas on the skull sutures, about 50% are found in or adjacent to the [[orbit (anatomy)|orbit]].<ref>{{EMedicine|oph|620|Orbital dermoid cyst}}</ref> Limbal dermoid is a [[choristoma]], not a teratoma.

Teratoma qualifies as a [[rare disease]], but is not extremely rare. Sacrococcygeal teratoma alone is diagnosed at birth in one out of 40,000 humans. Given the current human population and birth rate, this equals five per day or 1800 per year. Add to that number sacrococcygeal teratomas diagnosed later in life, and teratomas in other locales, and the [[Incidence (epidemiology)|incidence]] approaches 10,000 new diagnoses of teratoma per year.{{citation needed |date=February 2016}}

==Other animals==
Ovarian teratomas have been reported in [[mare]]s,<ref name="pmid15065985">{{cite journal | vauthors = Catone G, Marino G, Mancuso R, Zanghì A | title = Clinicopathological features of an equine ovarian teratoma | journal = Reproduction in Domestic Animals = Zuchthygiene | volume = 39 | issue = 2 | pages = 65–69 | date = April 2004 | pmid = 15065985 | doi = 10.1111/j.1439-0531.2003.00476.x | hdl = 11581/112802 }}</ref>
[[mountain lion]]s,<ref>{{cite web |url=https://www.cnn.com/2016/01/09/us/idaho-deformed-mountain-lion/ |title=Deformed Mountain Lion a mystery |author=Artemis Moshtaghian |date=January 11, 2016 |website= CNN|publisher=Cable News Network }}</ref><ref name="pmid16363331">{{cite journal | vauthors = Lefebvre R, Theoret C, Doré M, Girard C, Laverty S, Vaillancourt D | title = Ovarian teratoma and endometritis in a mare | journal = The Canadian Veterinary Journal | volume = 46 | issue = 11 | pages = 1029–1033 | date = November 2005 | pmid = 16363331 | pmc = 1259148 }}</ref> and canines.<ref>{{cite journal | vauthors = Gruys E, van Dijk JE | title = Four canine ovarian teratomas and a nonovarian feline teratoma | journal = Veterinary Pathology | volume = 13 | issue = 6 | pages = 455–459 | year = 1976 | pmid = 1006958 | doi = 10.1177/030098587601300609 | s2cid = 46250641 }}</ref> Teratomas also occur, rarely, in other species.<ref name="pmid18622858">{{cite journal | vauthors = López RM, Múrcia DB | title = First description of malignant retrobulbar and intracranial teratoma in a lesser kestrel (Falco naumanni) | journal = Avian Pathology | volume = 37 | issue = 4 | pages = 413–414 | date = August 2008 | pmid = 18622858 | doi = 10.1080/03079450802216660 | s2cid = 748134 | doi-access = free }}</ref>

== Use in stem cell research ==
Pluripotent stem cells including human induced pluripotent stem cells have a unique property of being able to generate teratomas when injected in rodents in the research laboratory.<ref>{{cite journal | vauthors = Gutierrez-Aranda I, Ramos-Mejia V, Bueno C, Munoz-Lopez M, Real PJ, Mácia A, Sanchez L, Ligero G, Garcia-Parez JL, Menendez P | display-authors = 6 | title = Human induced pluripotent stem cells develop teratoma more efficiently and faster than human embryonic stem cells regardless the site of injection | journal = Stem Cells | volume = 28 | issue = 9 | pages = 1568–1570 | date = September 2010 | pmid = 20641038 | pmc = 2996086 | doi = 10.1002/stem.471 }}</ref> The roots of this observation has been attributed to [[Leroy Stevens]] of the [[Jackson Laboratory]].<ref>{{cite web |title=A Stem Cell Legacy: Leroy Stevens |url=https://www.the-scientist.com/news/a-stem-cell-legacy-leroy-stevens-56114 |website=The Scientist Magazine® |language=en}}</ref> In 1970, Stevens noticed that the cell populations that gave rise to teratomas were very similar to the cells of very early embryos. 
For this reason, the so-called "teratoma assay" is one of the gold-standard validation assays for pluripotent stem cells.<ref>{{Cite web| vauthors = Knoepfler P |date=2021-01-14|title=What is a teratoma? Research & treatment|url=https://ipscell.com/2021/01/what-is-a-teratoma-research-prevention-treatment/|access-date=2021-02-07|website=The Niche|language=en-US}}</ref> Because differentiated human pluripotent stem cells are being developed as the basis for numerous regenerative medicine therapies, there is concern that residual undifferentiated stem cells could lead to teratoma formation in injected patients, and researchers are working to develop methods to address this concern.<ref>{{cite journal | vauthors = Lee MO, Moon SH, Jeong HC, Yi JY, Lee TH, Shim SH, Rhee YH, Lee SH, Oh SJ, Lee MY, Han MJ, Cho YS, Chung HM, Kim KS, Cha HJ | display-authors = 6 | title = Inhibition of pluripotent stem cell-derived teratoma formation by small molecules | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 110 | issue = 35 | pages = E3281–E3290 | date = August 2013 | pmid = 23918355 | pmc = 3761568 | doi = 10.1073/pnas.1303669110 | doi-access = free | bibcode = 2013PNAS..110E3281L }}</ref>

New research has looked at utilizing the human teratoma in chimeric animal studies as a promising platform for modeling multi-lineage human development, pan-tissue functional genetic screening, and tissue engineering.<ref>{{Cite journal |last1=McDonald |first1=Daniella |last2=Wu |first2=Yan |last3=Dailamy |first3=Amir |last4=Tat |first4=Justin |last5=Parekh |first5=Udit |last6=Zhao |first6=Dongxin |last7=Hu |first7=Michael |last8=Tipps |first8=Ann |last9=Zhang |first9=Kun |last10=Mali |first10=Prashant |date=2020-11-25 |title=Defining the Teratoma as a Model for Multi-lineage Human Development |journal=Cell |volume=183 |issue=5 |pages=1402–1419.e18 |doi=10.1016/j.cell.2020.10.018 |issn=1097-4172 |pmc=7704916 |pmid=33152263}}</ref>

== References ==
{{reflist}}

{{NCI-cancer-dict}}

== External links ==
{{Wikiquote}}
{{Commons category|Teratomas}}
{{wiktionary|teratoma}}
*humpath pathology images [http://www.humpath.com/spip.php?page=article&id_article=2657 #2657] {{Webarchive|url=https://web.archive.org/web/20170901031726/http://www.humpath.com/spip.php?page=article&id_article=2657 |date=2017-09-01 }} (Teratomas), [http://www.humpath.com/spip.php?page=article&id_article=4541 #4541] {{Webarchive|url=https://web.archive.org/web/20170901031732/http://www.humpath.com/spip.php?page=article&id_article=4541 |date=2017-09-01 }} (Mature teratoma), [http://www.humpath.com/spip.php?page=article&id_article=5350 #5350] {{Webarchive|url=https://web.archive.org/web/20170901031656/http://www.humpath.com/spip.php?page=article&id_article=5350 |date=2017-09-01 }} (Immature teratoma)
*{{EMedicine|med|2248|cystic teratoma}} (also [https://web.archive.org/web/20070930200400/http://www.emedicine.com/cgi-bin/foxweb.exe/searchengine@/em/searchengine?boolean=and&book=all&maxhits=100&HiddenURL=&query=teratoma search EMedicine for all articles containing the word ''teratoma''])

{{Medical resources
| DiseasesDB = 3604
| ICD10 = {{ICD10|C22.7}}, {{ICD10|C56}}, {{ICD10|C62}} ([[ILDS]] C62.930), {{ICD10|D13.4}}, {{ICD10|D27}}, {{ICD10|D29.2}}, {{ICD10|O33.7}}, {{ICD10|O66.3}}
| ICD9 = 
| ICDO = 9080
| OMIM = 
| MedlinePlus = 
| eMedicineSubj = med
| eMedicineTopic = 3449
| MeshID = D013724
| diseasesDB_mult = {{DiseasesDB2|12952}} {{DiseasesDB2|12966}}
| SNOMED CT = 36591000119102
}}

{{Germ cell tumors}}
{{Skin tumors, dermis}}
{{Genital neoplasia}}
{{Male genital neoplasia}}

{{Authority control}}

[[Category:Congenital disorders]]
[[Category:Obstetrics]]
[[Category:Male genital neoplasia]]
[[Category:Anatomical pathology]]
[[Category:Pediatric cancers]]
[[Category:Dermal and subcutaneous growths]]
[[Category:Gynaecological cancer]]
[[Category:Induced stem cells]]
[[Category:Wikipedia medicine articles ready to translate]]