Prurigo nodularis: a reappraisal of the clinical and histologic features.

Study of 14 patients with prurigo nodularis revealed that clinically the lesions were multiple, verrucous, and discrete and were set in normal-appearing skin. Microscopically, the lesions showed a vascular acanthomatous mass. The dermal nerves showed a tendency toward hyperplasia in parallel with the epidermal and vascular changes, but no evidence of neuroma formation was seen. Electron microscopic examination showed disorganization of the normal pattern of the myelin sheaths and axons of the dermal papillary nerves. The presence of epidermal mast cells was noted in the biopsy specimens of prurigo nodules from eight of the 14 patients.