Myospherulosis in renal cell carcinoma

Objective.-To study retrospectively the identification, characteristics, an d localization of myospherulosis in different types of renal cell carcinoma s. Design.-Twenty-seven consecutive renal cell carcinomas treated by radical n ephrectomy in 1 year were studied. All the tumor and nontumor slides were e xamined for myospherulosis. The demographic data, histological type of rena l cell carcinoma, Robson stage, and Fuhrman grades were recorded. Results.-Myospherules were found in 10 cases. They were associated with the clear cell type and a higher nuclear grade. The cell type remained the onl y significant factor when these 2 factors were tested together with the tum or stage by logistic regression. Myospherulosis tended to be found in young er patients but was not associated with the sex or the side of the tumor. T hey were scattered within tumor cystic spaces or among sheets of tumor cell s. Some of the myospherules might arise from histiocytes or even tumor cell s. Compared with previous reports of myospherulosis associated with exogeno us or endogenous lipid, the myospherules associated with renal cell carcino ma were smaller and more uniform in size. There is no associated fibrosis o r foreign body giant cell reaction. Conclusion.-As far as we know, this is the first report of myospherulosis o ccurring in malignant tumors in human, and their associated features are di fferent from those previously described for myospherulosis related to exoge nous or endogenous lipid.