Artifactual Cystic Spaces in Prostatic Transurethral Resections and Related Specimens: A Potential Diagnostic Confounder.

Aims. Histopathologic benign mimickers of prostate cancer have mostly focused on glandular mimics, with non-glandular mimics mainly limited to inflammatory conditions. While there is a paucity of literature recognizing small cystic (presumably artifactual) spaces in transurethral resection specimens, in some instances they can become florid enough to mimic vascular or epithelial neoplasms. Herein, we detailed histologic, immunophenotypic, and clinicopathologic findings in a large series of specimens showing prominent diagnostically confounding cystic spaces. Methods and Results . Sixty specimens were obtained (50 transurethral resections, 7 aquablations, 3 laser enucleations), from 17 different surgeons. Seven specimens had concurrent genitourinary pathology (4 prostatic adenocarcinoma, 1 solitary fibrous tumor, 1 prostatic atypia, 1 urothelial carcinoma in situ). The extent of cystic change among overall tissue examined ranged from 1 mm-8 mm (mean 3.4 mm), with luminal content of cystic spaces characterized as empty (72%), both empty and fluid-like (17%), and both empty and mucin-like (11%; mucin histochemical stain was negative on all specimens). Notable differences in degree of tissue cautery artifact or inflammation was not found. Immunohistochemistry performed on 30 specimens showed cystic spaces negative for S100, ERG, pankeratin, and CD45. Conclusion . Although artifactual in nature, in some instances small cystic spaces encountered in prostatic transurethral resections and more novel related procedures can become florid enough to warrant recognition as a potential diagnostic confounder of vascular or epithelial neoplasms.