Bilateral renal tumors; conventional clear cell carcinoma and contralateral t(6;11)/t(X;17)-like tumor : Histomorphologic, immunohistochemical, ultrastructural and molecular genetic studies including the report of a novel mutation in the VHL gene

A 34-year-old pregnant woman with bilateral kidney tumors 9.5 and 2.5 cm in maximum diameter is presented. The larger tumor was clear renal cell carcinoma. The smaller contralateral tumor was focally HMB45 positive and had unusual histomorphology, including features resembling clear renal cell carcinoma with features of both t(6;11)- and t(X;17)/ASPL-TFE3 carcinomas. This tumor displayed a complex karyotype. A novel germ line mutation in the VHL gene (c.439A>G/p.I147V) was also identified in this patient.