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A 54-year-old Caucasian man presented to the dermatology clinic for evaluation of a tumor on his right forearm. A small “red bump” that first appeared about six weeks earlier had grown rapidly and developed a crusted center. The patient recalled no preceding trauma to the site and had no personal or family history of skin cancer. The lesion had not yet been treated. On examination, a 1.5-cm, erythematous, crater-shaped nodule was visible on the right forearm. The indurated nodule had rolled borders and a central hyperkeratotic core. There was no regional lymphadenopathy. Shave biopsy revealed a well-differentiated squamous cell neoplasm with glassy keratinocytes and a central core of hyperkeratosis.

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