Folliculosebaceous Cystic Hamartoma of the Eyelid: A Case Report.

Folliculosebaceous cystic hamartoma (FSCH) is a cystic cutaneous entity characterized by a cystic folliculosebaceous development accompanied by mesenchymal components, often comprising adipocytes, variable fibrous stroma, and small vascular channels. We report a case of a 66-year-old female patient with a painless lesion on her right upper eyelid causing mechanical ptosis. On the tarsal surface of the eyelid, a fungating mass with a prominent vessel and yellowish deposits was visible. The differential diagnosis considered was that of a benign sebaceous eyelid mass, such as a sebaceous hamartoma or trichofolliculoma, and sebaceous gland carcinoma. The patient underwent complete excision of the lesion with eyelid reconstruction. Histopathologically, it exhibited a well-circumscribed, unencapsulated lesion with a central dilated cystic space lined by attenuated squamous epithelium, containing sparsely distributed keratin flakes, and surrounded by numerous sebaceous lobules. The background fibrous stroma showed numerous foamy histiocytes, smaller empty dilated cystic spaces, spindle cells, and fat spaces. FSCH of the eyelid is an extremely rare condition, requiring careful differential diagnosis in patients presenting with a papulonodular mass of the eyelid. The clinical relevance lies in its potential to mimic both benign and malignant eyelid tumors, particularly sebaceous gland carcinoma, making accurate histopathological evaluation essential to avoid a misdiagnosis.