Huge tumor-like subacromial bursitis associated with rheumatoid arthritis

We report a rare case of a huge subacromial bursitis in rheumatoid arthritis. A solid tumor was initially suspected because it was very large with no apparent local sign of inflammation, and because no fluid retention was observed. We performed radiograms, a plain computed tomogram, a (99)mTc-MDP bone scintigram, a (67)Ga-citrate scintigram, and a digital subtraction arteriogram, which all indicated no evidence of tumor. Finally, a bursogram proved the mass to be a huge enlarged subacromial bursa. Surgical exploration revealed that the bursa contained 450 g of a yellowish, jelly-like substance, which was considered to be a thick collection of fibrin. No recurrence was noted at a follow-up 16 years after surgery.