The most common cause of bilateral symmetrical polyarthritis in the small joints is rheumatoid arthritis. However, if seronegative arthritis is involved, it could be the case that other underlying causes need to be diagnosed. This is particularly important for those coming from or living in developing countries where infectious causes should always be considered. The case of a young Nepali woman is presented in this article. She was referred as a case of seronegative rheumatoid arthritis for DMARDs therapy but this was not the case due to her origin from Nepal and seronegativity for RF, Anti-ccp, and ANA as well as faint macular skin lesions over her face and upper extremities, which the patients are not aware of. Consequently, skin biopsy was carried out which subsequently confirmed that the infectious cause of her polyarthritis was leprosy.
LEARNING POINTS: Bilateral symmetrical seronegative inflammatory arthritis of rheumatoid type is very common.However, when both RF and anti-ccp are negative, other possible secondary causes including infection should be considered, especially in patients from areas where disease is endemic.In this case lepromatous leprosy was the cause of the patient's presumed rheumatoid arthritis and all her arthritis resolved after her leprosy had been treated.
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