Diagnostic Complexities and Management of Gouty Arthritis With Suspected Seronegative Rheumatoid Arthritis and Malignancy in an Elderly Male.

Rheumatoid arthritis (RA) and gout are two distinct types of inflammatory arthritis with significant morbidity. While RA is characterized by autoimmune synovitis, gout is defined by the deposition of urate crystals. Diagnosing these conditions becomes particularly challenging in patients with negative serological markers for RA, compounded by the patient's advanced age and potential for malignancy. This case involves a 77-year-old male with chronic gout, hypertension, chronic atrial fibrillation on edoxaban, diastolic congestive heart failure, and chronic kidney disease stage 3B, presenting with left knee pain and limited mobility. Despite negative serology for RA (rheumatoid factor (RF) <20.0 IU/ml, anti-CCP2 antibodies 1.2 U/mL), the clinical presentation raised suspicion for RA. Imaging revealed significant synovial hypertrophy and multiple periarticular lesions suggestive of chronic gouty tophi rather than RA or malignancy. The patient was managed with allopurinol, prednisolone, and colchicine and referred to rheumatology for further evaluation. Approximately 30% of RA patients may present with negative serological markers, complicating the diagnosis. Differentiating RA from gout is crucial due to differences in management strategies. Imaging modalities such as MRI and CT are essential in identifying characteristic changes of both conditions, such as synovial hypertrophy in RA and tophi in gout. In elderly patients, the possibility of malignancy should also be considered. This case highlights the complexity of diagnosing gouty arthritis mimicking seronegative RA, especially in elderly patients where the risk of malignancy must be considered. It underscores the need for comprehensive clinical and imaging evaluations and personalized treatment plans in managing patients with multiple comorbidities.