Lymphoma presenting as autoimmune rheumatic disorder: clinical overlap and diagnostic considerations.

Lymphomas are a heterogeneous group of malignancies arising from various lymphocyte subtypes, frequently presenting with systemic symptoms and multi-organ involvement. Their clinical features can closely resemble those of rheumatological diseases, presenting a significant diagnostic challenge. Rheumatic-like manifestations in patients with lymphoma may result from paraneoplastic syndromes - immune-mediated, indirect effects of the malignancy - or direct infiltration of joints and musculoskeletal tissues. Despite this overlap, there is a notable lack of structured, comprehensive guidance on how undiagnosed lymphomas may mimic rheumatological conditions. This review outlines the wide spectrum of rheumatological presentations associated with lymphoma, including inflammatory arthritis, hypertrophic osteoarthropathy, myositis, Paget's disease, remitting seronegative symmetrical synovitis with pitting edema, and systemic features that resemble autoimmune disorders. These clinical manifestations are often accompanied by the presence of autoantibodies and hypocomplementemia, further complicating the diagnostic process. Distinguishing between primary rheumatological diseases and lymphoma-related manifestations is critical to avoid delays in diagnosis and the inappropriate use of immunosuppressive therapies, which may worsen an undetected malignancy. This review underscores the importance of a thorough diagnostic approach - including imaging, tissue biopsy, and advanced hematologic testing - before initiating or escalating treatment in patients with atypical, refractory, or rapidly progressive symptoms. By raising clinician awareness and encouraging continued research into improved diagnostic strategies, this work aims to facilitate earlier recognition of lymphomas masquerading as rheumatic diseases, ultimately improving patient outcomes.