Suprasellar germinoma in three lake whitefish (Coregonus clupeaformis)

Suprasellar germinomas were identified in three wild-caught lake whitefish (Coregonus clupeaformis) from the St. Lawrence River, Quebec, Canada. Histo logically, the three tumors expanded the subarachnoid space of the ventral surface of the brain immediately adjacent to the pituitary gland and, in on e case, infiltrated the adjacent neuropil. These tumors were characterized by nests and sheets of round cells with a high mitotic rate, separated by a scant amount of loose fibrovascular stroma. The stroma was infiltrated by a moderate number of small mononuclear cells, including rare CD3-immunoreac tive lymphocytes. This is the first report of intracranial germinoma in a f ish species.