Variation among giant rice bodies: report of four cases and their clinicopathological features

Objective: To report four cases of rice bodies (RBs) showing remarkable siz e variations and discuss their pathogenesis. Design and patients: Based on analysis of the clinical data, we speculate o n the pathogenesis of RBs using immunohistochemical and ultrastructural met hods. 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 pa tients. T2-weighted MR imaging was very useful for diagnosis of the RBs, al lowing their clear delineation from the bursal fluid. The RBs consisted of a layered proteinaceous substance with vague targetoid cut surfaces. Much f ibrin and a lesser amount of collagen fibers were recognized together with various mononuclear cells, which were few in number and predominantly T cel ls. The bursae and synovial sheath had multiple fibrinoid spheroids at the luminal surface. Conclusion: Fibrinoid nodular deposits probably became detached, forming th e nuclei of RBs and growing to a giant RE 65 mm in diameter.