Germ cell tumors


Editorial Board Member: Jennifer A. Bennett, M.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Aurelia Busca, M.D., Ph.D.
Carlos Parra-Herran, M.D.

Topic Completed: 17 July 2020

Minor changes: 5 January 2021

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed Search: Ovary teratoma immature [title] free full text[sb]

Aurelia Busca, M.D., Ph.D.
Carlos Parra-Herran, M.D.
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Cite this page: Busca A, Parra-Herran C. Teratoma-immature. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarytumorteratomaimmature.html. Accessed October 28th, 2021.
Definition / general
  • A malignant germ cell tumor consisting of a teratoma containing variable amounts of immature tissue (typically primitive neuroectodermal)
Essential features
  • Malignant germ cell tumor of the ovary composed of cells from the three germ layers, containing variable amounts of mature and immature tissue
  • Affects mostly young females < 20 years old
  • Grossly solid ovarian tumor mass with necrosis and hemorrhage on cut sections
  • Grading is performed based on the amount of immature neuroepithelium
  • Can have associated nodal or peritoneal gliomatosis (presence of mature neural tissue), which increases risk of recurrence
  • Grading and stage are the most important factors for prognosis, greatly improved after chemotherapy
  • Immature teratoma
ICD coding
  • ICD-O: 9080/3 - teratoma, malignant, NOS
  • Ovary
  • Abnormal differentiation of fetal germ cells
  • 2 pathogenetic models for ovarian teratomas, similar to their testicular counterparts:
    • Pure mature and immature teratomas derived from no transformed ovarian germ cells
    • Teratomatous components of mixed germ cell tumors derived from their associated nonteratomatous components
  • Pure mature and immature teratomas do not have i(12p) or 12p amplification but these abnormalities are identified in both teratomatous and nonteratomatous components of mixed germ cell tumors, supporting a different pathogenesis for pure versus mixed tumors (Mod Pathol 2006;19:766)
  • 25% of cases with immature teratoma have peritoneal implants composed of mature glial tissue (gliomatosis peritonei); this phenomenon is thought to arise from metaplasia of submesothelial cells in response to growth factors secreted by the ovarian tumor, rather than a true metastatic process (Hum Pathol 1976;7:625, Hum Pathol 2004;35:685, Int J Gynecol Cancer 2015;25:244, Mod Pathol 2015;28:1613)
  • Rarely, also have mature glial tissue present in lymph nodes (nodal gliomatosis), usually with associated gliomatosis peritonei
  • Prognosis is good and the presence of nodal gliomatosis does not warrant chemotherapy (J Ovarian Res 2016;9:45, Mod Pathol 2015;28:1613)
  • No known causative agents
Clinical features
  • Associated with symptoms of rapidly growing abdominal mass, pain, distention, torsion
  • Growing teratoma syndrome: immature teratoma status post neoadjuvant chemotherapy and consists of persistence or enlargement of ovarian tumor with normalization of serum markers
  • A combination of clinical, radiological and laboratory findings: rapidly enlarging adnexal mass in a young patient with mildly elevated AFP and typical radiological findings raises the possibility of immature teratoma
  • Requires histological examination for confirmation of diagnosis and grading
  • Low level increase of alpha fetoprotein (AFP)
  • High levels of AFP suggest the presence of a yolk sac tumor component (mixed germ cell tumor)
Radiology description
Radiology images

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Complex ovarian mass

Prognostic factors
  • Older age at diagnosis, higher stage and grade confer worse prognosis but overall improved after chemotherapy, with 72% survival for stage IV disease (Gynecol Oncol 2016;142:261, Gynecol Oncol 2016;142:446)
  • Grade is the most important risk factor for relapse across all age groups
  • In a study of 98 pediatric patients and 81 adult patients, there were no relapses in grade 1 patients, irrespective of stage or age and only 1 adult patient with a grade 2 tumor relapsed (Cancer 2016;122:230)
  • In patients with grade 3 tumors, recurrence rate was 21% in the pediatric cohort and 20% in the adult cohort, and was significantly associated with stage (Cancer 2016;122:230)
  • Higher risk of recurrence with presence of gliomatosis peritonei or lymph node gliomatosis but similar overall survival (Virchows Arch 2012;461:299, J Ovarian Res 2016;9:45)
Case reports
Gross description
  • Usually unilateral ovarian masses with mean size 16 cm (range 5 - 42 cm) (Int J Gynecol Pathol 1994;13:283)
  • Solid with cystic areas or mostly solid; hemorrhage and necrosis on cut sections
  • Contralateral ovary with mature teratoma in 9% of cases
Gross images

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Ovarian immature teratoma

Frozen section description
  • Extensive sampling may be needed to include areas of immature teratoma at the time of frozen section in cases where a preoperative diagnosis of immature teratoma is suspected; sample nodular, soft appearing and mass forming areas
Microscopic (histologic) description
  • Variable amounts of mature elements from all three germ layers, admixed with immature elements, mostly neuroectodermal
  • Immature neuroepithelium can be spindled (sarcomatoid) or with rosette, pseudorosette and primitive tubule formation, the latter is easier to recognize
  • Cells appear primitive, with scant cytoplasm, hyperchromatic nuclei and frequent mitoses, which helps differentiate the immature elements from mature brain tissue
  • Only immature neuroepithelium used for grading, so important to recognize as such on histological slides
  • Original grading system (Cancer 1976;37:2359)
    • Grade 1: < 1 low power field (40x) in any slide
    • Grade 2: ≥ 1 but < 3 low power fields in any slide
    • Grade 3: ≥ 3 low power fields in any slide
  • Grade 2 and 3 tumors are considered high grade, therefore the updated grading system is 2 tiered, with improved reproducibility (Int J Gynecol Pathol 1994;13:283)
    • Low grade: < 1 low power field (40x) in any slide
    • High grade: ≥ 1 low power field in any slide
  • Peritoneal and nodal gliomatosis nodules consist of mature glial tissue, considered grade 0 for grading purposes; thorough sampling is required to identify immature tissue (metastatic immature teratoma component), which has a worse prognosis
  • Small foci of yolk sac tumor or embryonal carcinoma (< 3 mm) can be seen in immature teratomas without changing prognosis; WHO does not provide guidance regarding if these cases should be classified as a mixed germ cell tumor (Int J Gynecol Pathol 1994;13:283, Cancer 1976;37:2359)
  • Fetal cartilage can be present and is not considered an immature element
  • Neural tissue can have a prominent associated benign vascular proliferation with Wagner-Meissner-like corpuscles, which should not be interpreted as an immature component (Int J Gynecol Pathol 2002;21:16, Int J Surg Pathol 2008;16:320)
  • Other germ cell components (embryonal carcinoma or yolk sac tumor) may be present if the immature teratoma is part of a mixed germ cell tumor
Microscopic (histologic) images

Contributed by Aurelia Busca, M.D., Ph.D.
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Mature component

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Immature component

Virtual slides

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Large ovarian mass, ruptured on removal

Cytology description
Positive stains
Negative stains
Molecular / cytogenetics description
  • i(12p) and 12p amplification is present in immature teratomatous components of mixed germ cell tumors but not in pure immature teratomas (Mod Pathol 2006;19:766)
Sample pathology report
  • Left ovary, oophorectomy:
    • Immature teratoma (see synoptic report)
      • Tumor grade - 1 (low grade)
      • Tumor size - 16 cm
      • Ovarian surface involvement - present
Differential diagnosis
Board review style question #1
    Which of the following is true about gliomatosis peritonei found in ovarian immature teratoma?

  1. Considered a metaplastic rather than a true metastatic process
  2. Consists of immature glial tissue
  3. Has no impact on prognosis of immature teratoma
  4. Is used for grading of the immature teratoma
Board review style answer #1
A. Considered a metaplastic rather than a true metastatic process

Comment Here

Reference: Teratoma - immature
Board review style question #2

    Which of the following is true about grading of immature teratoma of the ovary?

  1. Grade does not impact prognosis
  2. Both grade 1 and grade 2 tumors are considered “low grade” in the two tier classification system
  3. Presence of immature elements in more than one low power field is in keeping with high grade
  4. Takes into account all histologic types of immature tissue
Board review style answer #2
C. Presence of immature elements in more than one low power field is in keeping with high grade

Comment Here

Reference: Teratoma - immature
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