A case of spontaneous nephroblastoma characterized by two distinctmorphologies in a Slc:CD(SD)IGS rat

摘要

We report a spontaneous case of nephroblastoma in a 26-week-old female Slc:CD(SD) rat.Macroscopically, there was a yellow mass in the left kidney that included another smallyellowish-white mass. Histologically, the mass was located mainly in the cortex of thekidney. The tumor showed two distinct morphologies corresponding to the macroscopicfindings: a blastemal cell dominant area (blastemal area) with primitive glomeruli andimmature tubules and a columnar epithelial tubule dominant area with blastemal cellcuffing on (epithelial area). The epithelial area was located inside the blastemal areaand the two morphologies were characterized by the lack of a transition region.Nephroblastoma is known to be biphasic or triphasic and showing transitional features. Toour knowledge, there is no report of such nephroblastoma comprising two histologicallydistinct areas without transition. Therefore, the two distinct morphologies of this casewith no transitional characteristic is a rare feature in nephroblastoma.