Langerhans cell granulomatosis manifested as pigmented villonodular synovitis

Area of Science:

• Rheumatology
• Pathology
• Dermatology

Background:

• Langerhans cell granulomatosis (LCG) is a rare clonal proliferative disorder of Langerhans cells.
• Synovial involvement in LCG is uncommon, with limited literature documenting its presentation.

Observation:

• A 38-year-old female jogger presented with hip joint symptoms mimicking pigmented villonodular synovitis.
• One year later, she developed characteristic LCG manifestations including skin and lymph node involvement.

Findings:

• This is the first reported case of LCG presenting clinically as villous synovial proliferation in the hip joint.
• The case expands the known spectrum of LCG musculoskeletal manifestations.

Implications:

• This case underscores the importance of considering LCG in the differential diagnosis of synovial proliferative lesions, particularly when accompanied by systemic signs.
• Distinguishing LCG from other histiocytic disorders like multicentric reticulohistiocytosis (MRH) is crucial for appropriate management.