Pachydermodactyly: A Case Report of a Little-Known and Benign Form of Digital Fibromatosis.

BACKGROUND Pachydermodactyly, a benign and self-limiting cause of cutaneous fibromatosis, is an under-recognized condition. This little-known condition is important, as it mimics inflammatory arthropathy. CASE REPORT A 16-year-old male presented with a 2-year history of progressive, asymptomatic soft tissue swelling of the proximal interphalangeal joints (PIPJs) affecting the second to fourth fingers bilaterally. He had participated in kayaking for the last 1-2 years. Physical examination revealed only painless, saccular, subcutaneous swelling around the PIPJs. Plain radiograph and MRI showed cutaneous thickening around the PIPJs, with no evidence of arthropathy. Blood investigations including inflammatory markers and autoimmune panel were normal. Skin biopsy showed thickened collagen in the dermis, acanthosis, and hyperkeratosis. The patient and family opted for observation and cessation of kayaking. Follow-up at 2 years showed stable disease. A diagnosis of pachydermodactyly was made. CONCLUSIONS Progressive, asymptomatic swelling of proximal interphalangeal joints, especially in young males, should prompt the consideration of pachydermodactyly as a potential differential diagnosis. Because of its benign course, correct recognition can help to prevent undue patient anxiety and avoid inappropriate investigation and treatment.