Caruncular Oncocytoma Mimicking Malignant Melanoma

To report a case of pigmented caruncular oncocytoma that simulated malignant melanoma and discuss the associated ultrasonographic and pathologic features.

Case report.

An 81-year-old female presented with a painless caruncular mass with a smooth brown surface suspicious for melanoma. Ultrasound biomicroscopy revealed a round mass with a large central cavity, more suggestive of a cystic rather than solid lesion. Following complete surgical resection, histopathology revealed a cystadenomatous lesion composed of bland cells with copious eosinophilic cytoplasm consistent with oncocytoma that had a central blood-filled cavity.

Oncocytoma is a benign tumor that can appear pigmented clinically and resemble melanoma. The definitive diagnosis requires histopathologic evaluation. Oncocytoma should be considered in the differential diagnosis of a pigmented caruncular mass.