Clinicopathological study of 5 cases of renal cell carcinoma with t(6;11)(p21;q12)

Renal cell carcinoma (RCC) with t(6;11)(p21;q12) has been incorporated into the recent WHO classification. We performed a clinicopathological study of 5 cases with such a tumor. The patients consisted of 4 males and 1 female. The age of patients ranged from 17 to 57 years with a mean age of 38.6 years. Tumor sizes ranged from 2.8 to 11 cm with a mean value of 6.5 cm. Despite immunotherapy and molecular-targeted therapy, one patient died of the disease 28 months after the surgery. Grossly, the cut surface of this tumor showed grayish white color in at least the focal area of all tumors. Furthermore, hemorrhage, daughter nodules and cystic changes were observed in two, three, and two tumors, respectively. Morpho-logically, all the tumors consisted of two components of large cells and small cells, and the latter surrounded basement membrane-like materials, forming rosette-like structures. Immunohistochemically, nuclei of tumor cells in all cases were positive for TFEB. Fluorescence in situ hybridization study confirmed the TFEB gene break in two tumors. Finally, urologists and pathologists should bear in mind that this tumor may occur in young adults to adults and might behave in an aggressive fashion. Break-apart FISH is useful for the definite diagnosis.