LAUSR

Background Rheumatoid arthritis is a common autoimmune disease with many extra-articular manifestations. Pure red cell aplasia is a rare manifestation of rheumatoid arthritis and is sparsely documented in the literature, with a variable clinical outcome following immunosuppressive therapy. Case presentation A 63-year-old Sinhalese female presented with transfusion-dependent anemia associated with deforming inflammatory arthritis. She also had leukopenia, right subclavian venous thrombosis, and generalized lymphadenopathy. The diagnosis of rheumatoid arthritis following initial clinical workup and additional blood and bone marrow investigations revealed pure red cell aplasia as a secondary manifestation of rheumatoid arthritis after excluding other secondary causes, such as infections, thymoma, thrombophilic conditions, and hematological malignancy. She responded well to oral prednisolone, cyclosporine A, and hydroxychloroquine, and she attained complete recovery in 2 months. Conclusion Pure red cell aplasia is a disabling illness that may lead to transfusion-dependent anemia, which may occur due to rare extrapulmonary manifestation of rheumatoid arthritis. The diagnosis of pure red cell aplasia secondary to rheumatoid arthritis may be challenging where hematological investigations, including bone marrow biopsy, will aid in the diagnosis, and early diagnosis and treatment will bring about a better outcome.