The features of radiation or chemotherapy cystitis mimicking invasive urothelial cancer are not widely known.
A search of the consultation files from our institution between January 1996 and September 2003 identified 20 patients with bladder biopsies showing cystitis mimicking invasive urothelial cancer.
The mean age at diagnosis was 69 years (range, 40-85 years); 80% were males. Complete history was not available in 1 patient. Seventeen patients had a history of pelvic irradiation (15 prostate cancer and 2 endometrial cancer). Two patients had systemic chemotherapy (1 metastatic colon cancer and 1 mixed connective tissue disease). All patients presented with hematuria. The mean time from radiation and/or chemotherapy to presentation was 27 months (range, 0-84 months). All cases showed epithelial proliferation that mimicked invasive cancer within the lamina propria, with marked proliferation seen in 45% of cases. Mild to moderate nuclear pleomorphism was seen in all cases. A characteristic feature was the presence of pseudoinvasive urothelial nests wrapping around the vessels associated with fibrin deposition. Most cases did not show any mitoses (75%). Ulceration was seen in 39% of cases. All cases showed some degree of hemorrhage, fibrin deposition and fibrin thrombi, fibrosis, and acute and chronic inflammation, with hemosiderin identified in 60% of cases. Edema and vascular congestion were common features (95% and 80%, respectively). Thickened vessels and vascular changes associated with radiation injury were identified in 75% of cases. Seventeen patients were followed for a mean of 9 months (range, 0.25-37 months), and none developed bladder cancer.
Radiation or chemotherapy cystitis can show epithelial proliferations that may be confused with invasive urothelial carcinomas. Other findings characteristic of radiation or chemotherapy cystitis, such as hemorrhage, fibrin, and vascular changes, are often seen in association with the epithelial proliferations and are helpful in distinguishing it from invasive cancer. Pathologists must be aware that these changes may be seen with a remote radiation or chemotherapy history, where this information may not be provided or known at the time of the biopsy evaluation.