Report of a family with idiopathic knuckle pads and review of idiopathic and disease-associated knuckle pads.

Knuckle pads are a rare, frequently overlooked, thickening of the skin usually overlying the extensor surface of the proximal interphalangeal joints. They are well- circumscribed, benign lesions that generally do not require treatment. Idiopathic knuckle pads must be differentiated from similar appearing lesions or trauma-induced pseudo-knuckle pads. Knuckle pads have been observed in association with autosomal dominant conditions such as Bart-Pumphrey syndrome, Dupuytren's contracture, Ledderhose disease, and Peyronie's disease. To the best of our knowledge, idiopathic familial knuckle pads have not previously been described in the English language literature. We describe a sister and brother with familial idiopathic knuckle pads with no associated conditions.