A 68-year-old man is seen for evaluation of a facial sore, which has been present for “at least a month.” It concerns him because, while the lesion is not painful, it won’t heal. The patient denies any preceding trauma to the area but does admit to having several skin cancers removed in his lifetime.
His lesion has been previously diagnosed as “pyoderma” and treated unsuccessfully with topical mupirocin and oral cephalexin.
He has held a number of jobs throughout his life, all of which involved being out in the sun all day—often seven days a week. And it wasn’t until he turned 45 that he finally started wearing a hat.
EXAMINATION
The lesion is an impressive, round, 1.2-cm nodule with extensive central ulceration. It has a rolled, translucent border and is tucked into the upper left nasolabial fold, directly adjacent to the alar bulb. It appears in the context of his fair, sun-damaged skin; he has several scars consistent with his history of skin cancer removal.
His skin elsewhere, while quite sun-damaged, is free of worrisome lesions.
A simple shave biopsy of the lesion is performed.
What is the diagnosis?