OBJECTIVE: To report four cases of rice bodies (RBs) showing remarkable size variations and discuss their pathogenesis. DESIGN AND PATIENTS: Based on analysis of the clinical data, we speculate on the pathogenesis of RBs using immunohistochemical and ultrastructural methods. The patients comprised three men and one woman, three with RBs in the subacromial bursae and one in the wrist synovial sheath, aged 28 (woman), 44, 50 and 81 (wrist) years, respectively. RESULTS: There were no particular differences in clinical data among the patients. T2-weighted MR imaging was very useful for diagnosis of the RBs, allowing their clear delineation from the bursal fluid. The RBs consisted of a layered protein- aceous substance with vague targetoid cut surfaces. Much fibrin and a lesser amount of collagen fibers were recognized together with various mononuclear cells, which were few in number and predominantly T cells. The bursae and synovial sheath had multiple fibrinoid spheroids at the luminal surface. CONCLUSION: Fibrinoid nodular deposits probably became detached, forming the nuclei of RBs and growing to a giant RB 65 mm in diameter.
OBJECTIVE: To report four cases of rice bodies (RBs) showing remarkable size variations and discuss their pathogenesis. DESIGN AND PATIENTS: Based on analysis of the clinical data, we speculate on the pathogenesis of RBs using immunohistochemical and ultrastructural methods. The patients comprised three men and one woman, three with RBs in the subacromial bursae and one in the wrist synovial sheath, aged 28 (woman), 44, 50 and 81 (wrist) years, respectively. RESULTS: There were no particular differences in clinical data among the patients. T2-weighted MR imaging was very useful for diagnosis of the RBs, allowing their clear delineation from the bursal fluid. The RBs consisted of a layered protein- aceous substance with vague targetoid cut surfaces. Much fibrin and a lesser amount of collagen fibers were recognized together with various mononuclear cells, which were few in number and predominantly T cells. The bursae and synovial sheath had multiple fibrinoid spheroids at the luminal surface. CONCLUSION:Fibrinoid nodular deposits probably became detached, forming the nuclei of RBs and growing to a giant RB 65 mm in diameter.