Rheumatoid Arthritis With Focal Segmental Glomerulosclerosis: A Case Report and Literature Review

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease primarily affecting the joints and, to a lesser extent, other systems. Renal involvement in RA is rare and might be due to the presence of systemic inflammation or the toxic effect of the medications used. Of the many types of renal diseases that can affect RA patients, focal segmental glomerulosclerosis (FSGS) is rarely encountered. In this report, we present a rare co-existence of RA and FSGS in a 50-year-old female with RA who was found to have FSGS as a possible cause of proteinuria and an extraarticular manifestation of RA. The patient's RA started as palindromic rheumatism, which progressed later to chronic symmetrical polyarthritis of the small and large joints. Along with the flare of her joint disease, she was found to have lower limb edema. Her workup showed persistent proteinuria of more than one gram per day. Renal biopsy showed unexpected findings of FSGS. Our patient was treated with tapering doses of steroids, methotrexate, candesartan, and a diuretic that controlled joint disease, blood pressure, and proteinuria. Follow-up at two years showed normal kidney function tests, a significant decline in proteinuria, and controlled joint disease. Our case portrays a possible relationship between FSGS as a cause of proteinuria in patients with RA. Physicians should be aware of the possibility of FSGS in RA patients, which can affect the management plan, medication efficacy, and overall prognosis.