Squamous Cell Carcinoma Developing from an Epidermal Inclusion Cyst on the Buttock.

Epidermal inclusion cysts of the skin rarely undergo malignant transformation into squamous cell carcinoma. We present a case of cutaneous squamous cell carcinoma in a 68-year-old male patient who exhibited clinical features resembling an infected epidermal inclusion cyst on the buttock. Presenting symptoms included rapid growth of the mass, tenderness, and purulent drainage. Although symptoms commonly indicate infection, underlying malignancy must remain a differential consideration. Definitive diagnosis requires histopathologic confirmation. The patient underwent wide excision of the mass and left inguinal node dissection, with the resultant defect covered by a posterior thigh flap. Wide local excision with appropriate margins remains the recommended treatment to ensure complete tumor clearance and minimize the risk of recurrence and pathological analysis essential for definitive diagnosis.