The nested variant of urothelial carcinoma arising in a fibroepithelial polyp: Report of a case and review of literature
A 30-year-old male presented with pain in the hypogastric region. X-rays and ultrasound revealed a stone in the bladder. While removing the stone surgically, a sessile polypoidal mass measuring 1.8 cm was seen at the posterosuperior wall of bladder, which was resected and sent for histopathology. On gross examination, it was a reddish-brown sessile polyp measuring 1.8 cm × 1.5 cm × 1.3 cm, which was submitted entirely for histopathological evaluation. Microscopy revealed a polyp covered by unremarkable epithelium [Figures and ]. The hyalinized vascular stroma was interspersed with many multinucleated bizarre stromal cells []. There were closely packed nests of bland-looking cells extending from the epithelium to the underlying muscularis propria infiltrating in between the smooth muscle and nerve bundles. The cells showed minimal atypia. The base of the polyp showed scattered bizarre stromal cells with occasional nests of the same bland-looking tumor cells.\nSpecial stains including Von Gieson and Masson's trichrome were done, which highlighted the transecting smooth muscle bundles clearly depicting the infiltrating nature of the tumor cells. Immunohistochemisty showed the cells strongly positive for pankeratin (CK AE1/AE3) [] and high molecular weight keratin (34BE12), which confirmed their epithelial nature. The cells were also positive for p53 expression [] and ki 67 index was high (50% approx.), predicting an aggressive course of the tumor.