Pachydermodactyly: Case report including clinical and histopathologic diagnostic pitfalls

Abstract

Pachydermodactyly (PDD) is a rare, benign condition characterized by swelling and thickening of the periarticular skin, most commonly at the proximal interphalangeal joints. Diagnosis is routinely made through correlation of clinical, histopathologic, and radiographic findings. Here, we report a case of PDD in a 25-year-old male, with emphasis on the clinical and histopathologic differential diagnosis and potential diagnostic pitfalls.

Pachydermodactyly associated with extensive computer gaming: A report of three cases

“…Histologically, pachydermodactyly displays epidermal acanthosis with compact hyperkeratosis and a thickened dermis with disorganized, coarse collagen bundles 5 . Interstitial mucin may be increased, 5 and there can be a mild increase in CD34‐positive dermal fibroblasts 5 . Occasionally, dermal elastic fibers are decreased 5 .…”

“…Interstitial mucin may be increased, 5 and there can be a mild increase in CD34‐positive dermal fibroblasts 5 . Occasionally, dermal elastic fibers are decreased 5 . Inflammation is notably absent 5 …”

Symmetrical digital swelling in an adolescent man

“…The clinical image is characteristic, and biopsy is not indispensable. Histological findings include: epidermal acanthosis with compact hyperkeratosis, mucin deposition in the dermis, thickening of collagen fibers, increased number of fibroblasts, and decreased elastic fibers 1,4,5 . As fibroblast proliferation is not a constant feature, some authors disagree with the classification of PDD as a form of fibromatosis 3…”

“…Differential diagnosis of PDD includes other dermatoses that cause skin thickening such as knuckle pads, lichen simplex chronicus and acanthosis nigricans, self‐healing cutaneous mucinosis (SHCM), and arthritis such as idiopathic juvenile arthritis (IJA) 1,4 …”

“…The diagnosis is based on clinical features, but when a biopsy is performed, it can reveal hyperkeratosis, acanthosis, coarse collagen bundles, and/or subcutaneous fibrosis, without an increase in dermal mucin. Therefore, histology might be not be helpful in distinguishing knuckle pads from PDD, especially in adults, who present dermal changes more frequently 4 …”