Idiopathic isolated bilaterally symmetrical brachymetacarpia of the fifth metacarpal in a woman with rheumatoid arthritis.

We report a rare case of idiopathic, isolated, and bilaterally symmetrical brachymetacarpia of the fifth metacarpal bones in a 60-year-old woman followed for seropositive rheumatoid arthritis. Despite the radiographic anomaly, the patient remained asymptomatic and had normal hand function. Extensive investigations ruled out syndromic or metabolic causes. This case emphasizes the importance of recognizing rare skeletal variants in rheumatologic evaluations.