A giant dermoid cyst of the orbit.

To describe a unique case of a non-germinomatous germ cell tumor, a giant orbital dermoid, present in adulthood. A 31-year-old male presented in our clinic with gradual, painless, progressive proptosis in the left eye since 28 years associated with gradual loss of vision. The left eye showed gross proptosis. Ocular structures could not be made out. Computed tomography scan showed a well-circumscribed oval heterogeneous mixed solid and cystic lesion completely filling the left orbit with calcification. The differential diagnosis was that of either teratoma or optic nerve glioma. The patient underwent excision of the lesion. Histopathology revealed a capsulated tumor with multiple cystic components filled with blood and eosinophilic material suggestive of a dermoid cyst. Non-germinomatous germ cell tumors may present atypically in adults and neglected benign dermoid cysts can attain massive size mimicking malignant lesions.