The final diagnosis was pseudocarcinomatous hyperplasia. D, Another example of pseudocarcinomatous hyperplasia in which the lamina propria was extensively involved by round, relatively bland, urothelial nests; note the proliferative background thrombosed vessels (arrow).
The differential diagnoses for pseudocarcinomatous hyperplasia include invasive urothelial carcinoma and the nested variant of urothelial carcinoma.
Based on the overall morphologic features, a diagnosis of pseudocarcinomatous hyperplasia (radiation cystitis) was rendered.
First described in 2000 by Baker and Young, (1) pseudocarcinomatous hyperplasia (also termed pseudocarcinomatous proliferation or radiation cystitis) is currently thought to be a benign, reactive condition most commonly seen in patients with a history of radiation therapy (1,2) ; approximately 75 unique cases have been described in the literature.
Patients with pseudocarcinomatous hyperplasia most often present with hematuria, but dysuria, lower abdominal pain, or patients undergoing surveillance biopsies for a prior diagnosis of urothelial carcinoma have also been reported.
These findings suggest that the development of urothelial carcinoma in these patients was due to urothelial neoplasia present elsewhere in the bladder, unrelated to their pseudocarcinomatous hyperplasia; therefore, although it is somewhat controversial whether radiation therapy itself is a risk factor for the development of urothelial carcinoma, pseudocarcinomatous hyperplasia itself is now thought to be a benign reactive condition with no proven increased risk for the development of subsequent urothelial carcinoma.
The most clinically significant differential diagnoses for pseudocarcinomatous hyperplasia include invasive high-grade urothelial carcinoma and the nested variant of urothelial carcinoma.
When invasive urothelial carcinomas are high grade, pleomorphic, and have marked atypia and numerous mitoses, the distinction between invasive urothelial carcinoma and pseudocarcinomatous hyperplasia is not difficult.
The base of nested urothelial carcinomas in well-oriented sections is generally irregular with an infiltrative edge compared to the generally linear, demarcated base seen in most cases of pseudocarcinomatous hyperplasia (Figure 2, D).
This process, termed pseudoepitheliomatous hyperplasia (PEH; or pseudocarcinomatous hyperplasia
), is potentially associated with organoid nevi, nonhealing ulcers, chronic dermatitides, reactions to underlying neoplasms, and selected infections of the skin.
Histologic Mimickers of Bladder Epithelial Neoplasms Mimickers of urothelial carcinoma in situ Reactive urothelial atypia Radiation atypia Polyomavirus infection Mimickers of exophytic papillary urothelial neoplasms Papillary and polypoid cystitis Nephrogenic adenoma Mimickers of invasive carcinoma Inflammatory lesions Pseudocarcinomatous hyperplasia
Von Brunn nests Cystitis cystica and cystitis glandularis Nephrogenic adenoma Endometriosis and related lesions Paraganglia Ectopic prostatic tissue Table 3.