Seronegative Bilateral Symmetrical Inflammatory Polyarthritis: Think Twice Before Starting Immunosuppression

Abstract

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.

Keywords: Seronegative rheumatoid arthritis; leprosy.

Figure 1

The non-blanching, non-scaly rash faint erythematous

Figure 2

The swollen wrists, MCPs, PIPs, MTPs, with moderate restriction of range of motion in the affected joints

Figure 3

Skin shows several foci of superficial and deep epithelioid granulomata with focal extension into the subcutaneous fat. Some of the granulomas are engulfing nerves. No interface changes are seen. There is no evidence of dysplasia or malignancy The special stains (Wade-Fite, ZN, and sliver) show a large number of Bacilli with a more diffuse histiocytic infiltrate consistent with leprosy. The more diffuse pattern and a large number of bacilli favor borderline leprosy subtype rather than tuberculoid subtype. Immunofluorescence studies using antibodies against IgG, IgA, IgM, C3, C1q, and fibrinogen are negative.