Eyelid sebaceous carcinoma masquerading as in situ squamous cell carcinoma.

Sebaceous carcinoma (SC) accounts for 1% to 5.5% of all eyelid malignancies. Diagnosis is often delayed because of its ability to masquerade as other periocular lesions both clinically and histologically. To promote a high index of suspicion among Mohs surgeons for SC when managing biopsy-proven in situ squamous cell carcinoma (SCC) of the eyelid, particularly the upper eyelid. This is a retrospective case review. A 77-year-old woman and a 71-year-old man were referred for Mohs micrographic surgery with a diagnosis of upper eyelid in situ SCC on biopsy. Intraoperatively, the presence of clear cell differentiation, in addition to extensive conjunctival involvement, leads to the correct diagnosis of SC. One case was subsequently found to have Muir Torre syndrome. Early diagnosis of eyelid SC leads to a better outcome and a higher survival rate. Hence, when managing in situ SCC of the eyelids, particularly the upper eyelid, Mohs surgeons should be aware of the possibility of SC and actively look for sebaceous cell differentiation or extensive conjunctival spread.