A year ago, this 60-year-old man noticed an asymptomatic lesion on the dorsum of his right hand. When it grew in size over the course of a few months, he showed it to his primary care provider, who believed it to be a wart and froze it with liquid nitrogen. This reduced its size, but only temporarily. It has since been treated with topical and oral antibiotics to no avail.
The patient has had several basal cell carcinomas removed from his face, arms, and trunk in the past.
EXAMINATION
On the mid dorsum of the patient’s right hand is a 1.5-cm ovoid nodule with a smooth surface and very firm feel. It appears in the context of fully sun-exposed, sun-damaged skin. Several scars are noted in the area, consistent with his history of sun-caused skin cancers.
The lesion is removed by deep shave biopsy, and the base curetted. The entire lesion is sent to pathology.
What’s the diagnosis?