Rare Presentation of Subacromial Bursitis Mimics Neoplasm in a Case of Rheumatoid Arthritis

INTRODUCTION: We report a rare case of massive subacromial bursitis in Rheumatoid Arthritis (RA) patient. A solid tumor was initially suspected because it was very large with no apparent local sign of inflammation or infection in a 69-year-old patient. Isolated subacromial bursa is an uncommon and it is usually small in size. This bursa usually does not enlarge enough to mimic a neoplastic lesion. The presence of huge swelling around shoulder usually raises the suspicion of neoplastic lesion. However, even in the presence of huge swelling, a benign lesion such as infection, cyst, or bursitis should be considered. This case report presents that even if swelling is huge, the benign lesion must be considered as a differential diagnosis of swelling around shoulder joint. CASE REPORT: We describe the clinical presentation, radiological investigations, and strategies for the management of a 69-year-old patient who was a known case of RA, and he was non-diabetic. Patient presented with massive swelling around shoulder for the past 6 years. We performed radiograms, a plain computed tomography, magnetic resonance imaging, a 99m Tc-MDP bone scintigram, and a 67Ga-citrate scintigram, which all indicated no evidence of tumor. It was treated by excision and no recurrence observed after 5 years. CONCLUSION: Massive subacromial bursitis is rarely reported in medical literature. Even if swelling is massive, the benign lesion must be considered as a differential diagnosis of swelling around shoulder joint.