Trilateral retinoblastoma

Findings:
MR images show a strongly enhancing mass in the pinal region which demonstrates isointensity on T2 weighted images. Moderate hydrocephalus is present, associated with transependymal flow. The left globe has been enucleated. A small focus of hypointensity is evident in the right globe, which likely represents calcification.

Differential Diagnosis:
The differential diagnosis of a pineal region mass includes germinoma, teratoma, and pineocytoma/blastoma. In this case, the associated findings of previous retinoblastoma on the left and small calcified tumor on the right would lead to a diagnosis of pineoblastoma.

Discussion:
Retinoblastoma is the most common primary intraocular tumor of childhood, and should be a primary consideration in the differential diagnosis of leukocoria. Intraocular calcifications in a child are indicative of retinoblastoma until proven otherwise, and the other causes of  leukocoria (i.e. PHPV, Coat's dz, Toxocara, ROP) are rarely if ever calcified. The tumors are thought to arise from primitive photoreceptor cells, and 25% are bilateral or multifocal. Invasion of the optic nerve portends a poor prognosis. 10% are hereditary, associated with a deletion on chromosome 13q. These patients are at risk for developing pineal tumors, extracranial sarcomas, and melanoma. When a patient with retinoblastoma develops a pineal tumor, the term trilateral retinoblastoma is used.

BACK TO MAIN PAGE