An update on pachydermodactyly and a report of three additional cases.

Pachydermodactyly is a benign condition characterized by symmetrical, painless, diffuse swelling of the skin on the lateral aspects of the proximal interphalangeal joints of the fingers. Histopathological examination shows epidermal hyperplasia, an increase of dermal collagen bundles and a slightly increased number of fibroblasts. We report three adolescent males with pachydermodactyly. We also review 20 published cases, and discuss the differential diagnosis, clearly distinguishing pachydermodactyly from 'true' and 'false' knuckle pads.