An eleven-year-old boy presented with progressive, painless, swelling of the skin overlying proximal interphalangeal joints of both hands since past year [Figure 1a]. There was no history of arthralgia or repeated mechanical stimulation of the involved skin. Examination revealed thickening and induration of the skin overlying the second through fifth proximal interphalangeal joints of both hands (right more than left), with slight deviation of the affected fingers. X-ray of the hands showed soft tissue thickening without any joint abnormality [Figure 1b]. Based on the clinical and radiological findings corroborated by histopathology, a diagnosis of pachydermodactyly (PDD) was rendered.
Figure 1.
(a) Thickening and induration of the skin overlying the second through fifth proximal interphalangeal joints of both hands (right more than left), with slight deviation of the affected fingers. (b) X-ray of the hands showed soft tissue thickening without any joint abnormality
PDD is a rare, benign digital soft tissue fibromatosis mostly affecting young men. The underlying pathogenesis remains speculative though mechanical stimulation is implied in its causation.[1,2] It has also been associated with many psychiatric disorders including mental retardation and Asperger syndrome. It can present with joint pain in addition to cutaneous involvement, and hence can be confused with close differential diagnoses such as juvenile idiopathic arthritis, rheumatoid arthritis, pachydermoperiostosis, thyroid acropachy, acromegaly, and knuckle pads. Treatment involves cessation of mechanical stimulation and treatment of any underlying psychiatric condition.
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References
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