Pseudo-knuckle pads: an unusual cutaneous sign of obsessive-compulsive disorder in an adolescent patient

Knuckle pads are discrete benign cutaneous lesions overlying the extensor surfaces of the fingers and hand joints and are unrelated to trauma, whereas pseudo-knuckle pads may be considered as a form of callosity that appears after repeated trauma. This type of knuckle pad has been described in children with obsessive behavior as "chewing pads" and in adults as occupational disorder. Cases of pachydermodactyly, benign fibromatosis of the fingers, have been described as the unusual forms of knuckle pads that usually affect young adult males. We believe that pseudo-knuckle pads, chewing pads or pachydermodactyly are terms which have been used to decribe the same clinical situation reported in different patients. Here we describe a 12-year-old male patient with pseudo-knuckle pads along the metacarpophalangeal joints developed secondary to repeated trauma reflecting obsessive-compulsive disorder characterized by a tic-like habit. He received fluvaksamine 25 mg/day. The lesions started to disappear after three months of therapy. The recognition of pseudo-knuckle pads by dermatologists and pediatricians is very important in adolescent patients because these lesions may be clues for diagnosis of serious psychiatric problems. The collaboration of a dermatologist or pediatrician with a psychiatrist is essential in the follow-up of these patients.