Pineal germinomas are the most common tumor of the pineal region accounting for ~50% of all tumors, and the majority (~80%) of intracranial germ cell tumors.
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Epidemiology
There is a marked male predominance with a M:F of ~13:1. Most patients are 20 years or younger at the time of diagnosis.
Clinical presentation
They can result in mass effect and compression of the tectal plate leading to obstructive hydrocephalus and Parinaud syndrome (upward gaze palsy).
Pathology
Pineal germinomas originate from totipotent primordial germ cells and are analogous to germ cell tumors arising in the gonads. There may be elevated CSF placental alkaline phosphatase and human chorionic gonadotropin (HCG) 5.
Macroscopic appearance
Pineal germinomas are typically round, solid, soft tan-white mass lesions. Necrosis and hemorrhage are not commonly a feature 5.
Microscopic appearance
Pineal germinomas are composed of cells with large nuclei and prominent nucleoli. Lymphocyte infiltration is a common feature, although the degree varies from case to case. Germinoma cells are positive for placental alkaline phosphatase on immunohistochemistry 5.
Radiographic features
See main article: intracranial germ cell tumors.
Treatment and prognosis
Leptomeningeal or intraventricular spread is not uncommon (occurring in 13% 2) at the time of diagnosis. Germinomas are receptive to radiation therapy and survival rates of ~85% are reported 3.
Differential diagnosis
See pineal region mass article.