Xanthomatosis in bilateral hands mimicking rheumatoid arthritis

Rationale: Xanthomatosis often accompanies familial hypercholesterolemia. This disease usually occurs in tendons, most commonly located in the Achilles tendon; occasionally it can also be seen in other systems. Although there are previous reports for bilateral hand extensor tendon involvement, to our knowledge there is no report in English literature regarding bilateral hands with small joint synovium presenting as rheumatoid arthritis. Therefore, the case that is presented in this report is unique. Patient concerns: An 18-year-old woman was admitted to our department because she presented with morning stiffness, joint deformation, and swelling in both hands. Computed tomography of the right hand showed soft tissue swelling on multiple small joints, including metacarpophalangeal and proximal interphalangeal joints, but without obvious bone destruction. There was soft tissue swelling around the small joints, which were hypointensities on T1-weighted and hyperintensities on T2-weighted images, not uniformly enhanced appearances on magnetic resonance imaging. Diagnoses: Biopsy from the 3rd metacarpophalangeal joint capsule of the left hand confirmed xanthoma. Interventions: She was treated with statin drugs to reduce blood fat. Outcomes: After 3 months of follow-up, no recurrence or complications were detected regarding a full range of motion remaining of the affected joints. Lessons: The young patient with symptoms of small joint synovium involved in both hands and the performance of magnetic resonance imaging similar to rheumatoid arthritis may be suffering from xanthomatosis. Abbreviations: Anti_ccp = anticyclic citrullinated peptide antibodies, ERA = early rheumatoid arthritis, LDLC = low-density lipoprotein cholesterol, MCP = metacarpophalangeal, MRI = magnetic resonance imaging, RA = rheumatoid arthritis, RF = rheumatoid factor.