Germinoma

Incidence

Germinomas account for 40% of pineal region masses, and for two thirds of the germ cell tumors.

Origin

Germinoma is histopathologically identical to seminoma of the testis.

Macroscopic appearance and general characteristics

The most important feature for differential diagnosis is the uniform aspect of the lesion, without evidence of cyst or calcification. The mass surrounds the pineal gland that classically is calcified. Male patients are affected two to 17 times more often than female patients. Peak age is in the second decade. Typical is the early spread along the surface of the brain or through CSF flow, with localization in or around the pituitary infundibulum, the anterior recess of the third ventricle, and along the surface of the spinal cord.

Microscopic appearance (image 2)

The tumor is composed of uniform cells, resembling primitive germ cells with large vesicular nuclei. Lymphocytic infiltration is often present.

Imaging features (see case reports)

- CT

Germinoma is seen as an homogenous slightly hyperdense mass. The pineal gland usually can be recognized as a prominent and calcified structure within the tumor.

Enhancement is intense and homogeneous.

- MRI

Germinomas are homogeneous tumors with a signal intensity equal to that of grey matter on both T1 a T2 weighted images. Enhancement is intense and homogeneous. Multiplanar imaging after Gadolinium injection helps to identify tumor seeding on the surface of the brain or spinal cord (image 3).

Therapy

Germinomas are very radiosensitive and respond well to specific chemotherapy. Five year survival is 75%.

Differential diagnosis

Pineal gland germinomas have to be differentiated from pineal cell tumors and astrocytomas of the quadrigeminal plate. Germinomas in the suprasellar recess have to be differentiated from pilocytic astrocytoma and other tumors (see pilocytic astrocytoma).

Case reports

Search:
Pineal region germinoma
Suprasellar germinoma
Pineal region germinoma with droplet metastases
Pineal region germinoma with suprasellar seeding

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