Sebaceous carcinoma with apocrine differentiation: a rare entity with aggressive behavior.

Sebaceous carcinomas are rare neoplasms but have aggressive behavior. Although they can be found anywhere in the body ocular region is the most common site which comprises 75% of all cases of sebaceous carcinomas. Due to their rarity, varied histopathological features, and diverse clinical presentation, their diagnosis is often delayed, sometimes by a year. They are divided on the basis of histological differentiation into well and poorly differentiated. Apocrine differentiation is a still rarer finding and only two cases have been reported in the literature so far. We report a case of sebaceous carcinoma with apocrine differentiation in a 60-year-old male who presented with a painless swelling in right upper eyelid for 2 months which was gradually progressive. Computed tomography (CT) scan was performed and a provisional diagnosis of hemangioma was made. The mass was excised and histopathological examination revealed it to be sebaceous carcinoma. However, there were areas with decapitation secretions and granular eosinophilic cytoplasm. These were positive for cytokeratin (CK) 7 and CK 19 which confirmed their apocrine nature. Therefore, a final diagnosis of sebaceous carcinoma with apocrine differentiation was made. Thus, it can be concluded that ocular sebaceous carcinomas with apocrine differentiation are extremely rare and have significant clinical importance since they can mimic a benign lesion and the nature of surgical intervention and follow up is more aggressive than that of simple sebaceous carcinoma alone.