Pigmented villonodular synovitis of the extensor tendon sheaths in a child

Area of Science:

• Orthopedics
• Pediatric Rheumatology
• Musculoskeletal Oncology

Background:

• Diffuse pigmented villonodular synovitis (DPVS) is a rare, benign neoplastic proliferation of the synovium.
• Typically affects large joints like the knee and hip, with intra-articular or tenosynovial involvement.
• Pediatric cases are infrequent, and extensor tendon sheath origin is exceptionally uncommon.

Observation:

• This report details the first documented case of DPVS originating in the extensor tendon sheaths of the hand in a pediatric patient.
• Clinical presentation included a gradually enlarging, painless mass over the dorsal aspect of the hand.
• Imaging revealed a well-defined lesion within the extensor tendon sheath.

Findings:

• Histopathological examination confirmed the diagnosis of DPVS, characterized by xanthoma cells, hemosiderin deposition, and multinucleated giant cells.
• The lesion demonstrated a localized, tenosynovial pattern of growth.
• No evidence of malignancy or systemic involvement was found.

Implications:

• This case expands the known spectrum of DPVS presentation in children.
• Highlights the extensor tendon sheaths of the hand as a potential, albeit rare, site for DPVS in pediatric patients.
• Emphasizes the need for high clinical suspicion and appropriate diagnostic workup for pediatric hand masses, even in the absence of typical joint involvement.