Typically occurs ~3 to 6 weeks after radiation of pelvic tumors.
Urothelium exhibits marked cytologic atypia characterized by nuclear pleomorphism, smudgy chromatin and cytoplasmic vacuolations, but with normal or maintained nuclear to cytoplasmic ratio (image A) & (image B).
Image C (click on the image above)
Image D (click on the image above)
Background stroma also exhibits pronounced atypia (image C).
Blood vessels are thickened and hyalinized (image D).
Lamina propria with edema or fibrosis.
Pseudocarcinomatous epithelial hyperplasia may develop which can closely mimic carcinoma.
Awareness of the history of prior pelvic radiation is important because of the morphologic mimicry to urothelial carcinoma.