Rapidly Enlarging Nodule on the Scalp

Abstract

A 72-year-old white manpresentedwith a 1-monthhistoryof a rapidly enlarging growth of the left frontal scalp. The lesion was nontender, and thepatientdeniedanyother signsor symptoms.Thepatient had a history of chronic solar damage and actinic keratoses but no cutaneous malignant lesions. His medical history included diverticulosis, dyslipidemia, and superficial venous thrombosis. He had a 43–pack-year history of cigarette smoking. Baseline laboratory findings included a hemogram, notable for a white blood cell count of 3100/μL (reference range, 4000/μL-11 000/μL), an absolute neutrophil count of 7000/μL (reference range, 16 000/μL-93 000 μL),andenlargedplatelets. (Toconvertwhitebloodcellcountandneutrophilcountto×109/L,multiplyby0.001.)Results fromserumchemical analysis, liver functions, and lacticdehydrogenase levelwerenormal. Physical examination revealed a healthy-appearing man with a solitary 3.0× 3.5 cmnodulewithmild erythema and a superficial excoriation (Figure 1). Therewasnoadenopathyof theheador neck. A punch biopsy specimenwas obtained (Figure 2 and Figure 3). What is your diagnosis?