CNS & pituitary tumors
Germ cell tumors
Germinoma
Author: Nat Pernick, M.D.
Last author update: 1 January 2006
Last staff update: 18 May 2023
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Germinoma CNS
Table of Contents
Definition / general | Staging / staging classifications | Case reports | Treatment | Gross description | Microscopic (histologic) description | Cytology description | Positive stains | Negative stains | Electron microscopy description | Differential diagnosis | Additional referencesCite this page: Pernick N. Germinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumorgerminoma.html. Accessed September 28th, 2023.
Definition / general
- Most common intracranial germ cell neoplasm
- Often teenagers and young adults
- Two - thirds male
- May be mixed with other germ cell tumors
- May derive from ectopic rests, transformation of resident germ cells or migration of germ cells late in development
- Most common site is pineal region
- Also anterior or posterior third ventricle, rarely fourth ventricle
- Rarely associated with dysgenetic syndromes
- Immunostains useful because biopsy is often small
- Relatively good prognosis (5 - 10 year survival is 75 - 95%) versus 25 - 40% for nongerminoma germ cell tumors (Pediatr Neurol 2002;26:369)
- Very sensitive to radiotherapy and chemotherapy; nongerminomatous germ cell tumors are less radiosensitive
- Metastases may be due to surgical displacement of tumor
- Spinal cord metastases occur in 10 - 15% of patients
Staging / staging classifications
- T1: smaller than 5 cm in diameter and located in the suprasellar, intrasellar or pineal region
- T2: larger than 5 cm in diameter and located in the perisellar region
- T3: may be smaller than 5 cm in diameter but invades and encroaches on the third ventricle
- T4: extends into the anterior, middle or posterior fossa
- N: not indicated for CNS tumors
- M0: no evidence of gross subarachnoid or hematogenous metastasis
- M1: microscopic tumor cells found in the CSF
- M2: gross nodular seeding in the ventricular system or cranial subarachnoid spaces
- M3: gross nodular seeding in the spinal subarachnoid spaces
- M4: metastasis outside the cerebrospinal axis
Case reports
- 23 year old man with headaches and visual difficulties (Arch Pathol Lab Med 2003;127:497)
Treatment
- Resection difficult due to high collagen content
- Radiation therapy helpful
Gross description
- Soft, gray-pink, homogenous
- Variable encapsulation
- Usually poorly circumscribed and infiltrative
Microscopic (histologic) description
- Resembles seminoma / dysgerminoma
- Large, epithelioid cells with abundant PAS+ cytoplasm, large, round nuclei and irregular and pleomorphic nuclei
- May have prominent nests of lymphocytes with occasional granulomatous inflammation that may obscure tumor cells (Neurol Med Chir (Tokyo) 2005;45:415)
- Lymphocytes may smear in small biopsies
- Frequent mitotic activity and necrosis
- Syncytiotrophoblasts in 14%
- Less anaplasia than embryonal carcinoma
- No cells intermediate in size between lymphocytes and large germinoma cells
Cytology description
- Loose fragments or single large pleomorphic and polygonal cells with vacuolated cytoplasm, enlarged oval nuclei and prominent nucleoli
- Frequent mitotic figures, naked nuclei, foamy background
- Also smashed lymphoid cells with streaking
Positive stains
- PLAP, PAS+ cytoplasm, CD117 / c-kit, OCT4 (strong, often diffuse)
Electron microscopy description
- Glycogen in cytoplasm, sparse cytoskeletal elements, prominent nucleoli
Differential diagnosis
- Carcinoma:
- Usually metastatic, keratin+, EMA+, 13% are PLAP+
- Embryonal carcinoma:
- 25% are PLAP+
