Germinomas are thought to originate from an error of development, when certain primordial germ cells fail to migrate properly.

[citation needed] The tumor is uniform in appearance, consisting of large, round cells with vesicular nuclei and clear or finely granular cytoplasm that is eosinophilic.

On gross examination, the external surface is smooth and bosselated (knobby), and the interior is soft, fleshy, and either cream-coloured, gray, pink, or tan.

[citation needed] Often, serum and spinal fluid tumor markers of alpha-fetoprotein and beta-HCG are tested.

[3] Since 1994, MeSH has defined germinoma as "a malignant neoplasm of the germinal tissue of the gonads, mediastinum, or pineal region"[4] and within its scope included both dysgerminoma and seminoma.

[citation needed] The diagnosis of an intracranial germinoma usually is based on biopsy, as the features on neuroimaging appear similar to other tumors.

The best results have been reported[citation needed] from craniospinal radiation with local tumor boost of greater than 4,000 centigray (cGy).

For this reason, treatment with these methods can offer excellent chances of long-term survival, even cure.

[citation needed] Although chemotherapy can shrink germinomas, it is not generally recommended alone unless radiation has contraindications.