Sebaceous carcinoma of the eyelid and adnexa commonly simulates other entities both clinically and pathologically. Between 1905 and 1981, 43 patients with sebaceous carcinoma of the eyelid were seen at the Mayo Clinic. Prior to establishing the diagnosis of sebaceous carcinoma, patients commonly carried multiple clinical diagnoses (mean = 2.2) and multiple microscopic diagnosis (mean = 1.7). the most common clinical diagnosis was chalazion. the patients' average age at the onset of symptoms was 61.5, with females predominating. the upper eyelid was most commonly involved. the conjunctival surface was involved alone in a statistically greater number of patients with metastatic disease (p 0.05). Second primary malignancies and/or radiation exposure was found in 11 patients, or 25% of our series. of the second primary malignancies, malignancies of the skin and breast were most common. Sebaceous carcinoma should be suspect in atypical presentations of common disorders and in cases in which clinical and pathol...