A Case of Mistaken Identity: Presumed Basal Cell Carcinoma Unmasked as Squamous Cell Carcinoma

INTRODUCTION: Basal cell carcinoma and squamous cell carcinoma are the most common malignant tumors of the eyelid. Although basal cell carcinoma is more common, squamous cell carcinoma can closely mimic its’ appearance, highlighting the need for an accurate diagnosis to guide timely and appropriate management. CASE REPORT: A 66-year-old Caucasian male presented for a routine eye exam without complaints. He denied pain, discomfort, flashes, floaters, or double vision. His medical history included type II diabetes, hyperlipidemia, sleep apnea, and hypertension. Slit lamp examination of the right eye revealed a large (~5 mm), nodular lesion with ulceration on the temporal margin of the right upper lid. Given its size, ulceration, and reported progression, the lesion was initially suspected to be basal cell carcinoma, and the patient was referred to an oculoplastic surgeon with coordinated dermatologic care. Histopathologic analysis of a shaved biopsy revealed a well-differentiated squamous cell carcinoma extending to the deep margins of the specimen. CONCLUSION: This report reviews the epidemiology, clinical presentation, management, and treatment of basal cell carcinoma and squamous cell carcinoma of the eyelid and presents a case in which a lesion initially presumed to be basal cell carcinoma was ultimately identified as squamous cell carcinoma on histopathology.