Infundibular Germinoma

This is a case of an infundibular germinoma. There is fusiform enlargement of the infundibulum with T1 signal isointense to white matter. The DWI and ADC maps demonstrate evidence of a cellular process with a high nuclear:cytoplasm ratio. The lesion demonstrates T2 isointense signal to white matter. There is heterogeneous postcontrast enhancement on the axial and sagittal postcontrast T1-weighted images. Germinomas are tumors of primordial germ cells, similar to seminoma or dysgerminoma of the gonads or mediastinum. Typical presentation includes a suprasellar mass in the setting of diabetes insipidus. Differential diagnosis includes craniopharyngioma, Langerhans cell histiocytosis, other nongerminomatous germ cell tumors and hypothalamic/chiasmatic astrocytoma.