Pachydermodactyly Presenting as Bilateral Proximal Interphalangeal Joint Skin Thickening in an Adolescent Male: A Case Report

Abstract

Pachydermodactyly is a rare, benign form of superficial digital fibromatosis characterized by asymptomatic periarticular thickening of the skin surrounding the proximal interphalangeal joints. Because of its resemblance to inflammatory arthropathies, it is frequently misdiagnosed, resulting in unnecessary investigations and inappropriate treatment. An 18-year-old right-hand-dominant male presented with a four-year history of gradually progressive, painless periarticular thickening involving the proximal interphalangeal joints of both hands, most prominently affecting the index fingers. He denied joint pain, morning stiffness, functional limitation, preceding trauma, repetitive mechanical friction, or systemic symptoms. Dermatological examination revealed symmetrical, firm, non-tender fusiform thickening involving the lateral and medial aspects of both proximal interphalangeal joints, with preserved joint mobility. Laboratory investigations, including complete blood count, erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, and anti-cyclic citrullinated peptide antibody, were within normal limits. Ultrasonography demonstrated localized dermal thickening without increased vascularity or synovitis, while plain radiographs showed preserved joint spaces without erosions or other osseous abnormalities. Based on the characteristic clinical presentation and supportive laboratory and imaging findings, a diagnosis of pachydermodactyly was established. As the patient was asymptomatic and had no cosmetic or functional concerns, conservative management with reassurance and observation was advised. At three-month follow-up, the lesions remained unchanged without development of new symptoms. Pachydermodactyly should be considered in adolescents presenting with painless periarticular digital thickening and normal laboratory and imaging findings. Awareness of this uncommon condition facilitates timely diagnosis, prevents unnecessary invasive investigations and immunosuppressive therapy, and enables appropriate conservative management.