COW-2021-31

CASE OF THE WEEK

2021-31/ August 2
Contributors: Dimitris Goutas, Andreas C. Lazaris

A 60-year-old man experiencing voiding difficulties due to prostate gland enlargement, unresponsive to medical treatment, underwent a transurethral resection of the prostate to alleviate his symptoms. Endoscopic evaluation of the prostatic urethra was unremarkable. The patient had no known history of carcinoma.

Quiz

1. What is the correct diagnosis?

a. High grade prostate adenocarcinoma

b. Urothelial carcinoma, probably of urinary bladder origin, invading prostatic stroma with large nested pattern

c. Primary invasive urothelial carcinoma of the prostate

d. Intraepithelial extension of urothelial carcinoma to periurethral prostatic ducts and acini

Urothelial carcinoma probably of urinary bladder origin, invading prostate stroma with a large nested pattern

The controversy surrounding such a scenario is whether to provide the clinicians and the patient with a diagnosis of direct invasion of urothelial carcinoma of the urinary bladder within the prostate stroma (pT4a) or of intraepithelial extension of an urothelial carcinoma, either of bladder origin secondarily involving the prostate or primarily arising in the prostatic urethra and extending through periurethral ducts into the stroma of the prostate, in any case without invasion (intraepithelial spread); in the latter case the tumor would be staged in accordance to the staging system of the urethra carcinoma (pT2). Since the patient had no known history of another carcinoma and a cystoscopic evaluation had not yet been performed, the decision was hard to make.

Immunohistochemical examination for basal markers can aid in decision-making. The selected markers for prostate basal cells, however, should not be expressed by the urothelial cancer cells; so, cytokeratin 34βE12 and p63 do not seem appropriate since a large proportion of urothelial carcinomas is immunopositive for these markers. What is important and needs to be highlighted, is that not all invasive urothelial carcinomas need to be of high grade or accompanied by an intense desmoplastic reaction 1,2. Large-nested urothelial carcinoma, although invasive and aggressive, has been reported to have a more indolent histological presentation, being of low grade and being composed of large nests arranged in an erratic and random distribution, commonly mimicking, when located in the lamina propria, an inverted low-grade pTa urothelial neoplasm 1,3. However, when arising in the bladder, it most commonly invades the detrusor muscle, a finding discriminating it from a non-invasive, inverted neoplasm. Interestingly, the regular contour of urothelial formations does not exclude invasiveness, when such formations are related to the detrusor muscle, to pericystic tissues or the prostate gland (as in the present case).

Of course, as far as the lamina propria of the bladder wall is concerned, a discrimination between stages pTa and pT1 is particularly difficult, when the urothelial nests’ relation to the detrusor muscle cannot be assessed. The random, dispersed distribution may raise suspicion of bladder lamina propria invasion (pT1), so the detrusor muscle should be adequately investigated in a future cystoscopy.

1. Guo A, Liu A, Teng X. The pathology of urinary bladder lesions with an inverted growth pattern. Chinese J Cancer Res. 2016;28(1):107-121. doi:10.3978/j.issn.1000-9604.2016.02.01

2. Agrogiannis G, Alamanis C, Karatrasoglou EA LA. Clinical Pathology of the Urinary Bladder. In: Lazaris AC, ed. Clinical Genitourinary Pathology – A Case Based Learning Approach. Springer; 2018:152-177.

3. Amin MB, Smith SC, Reuter VE, et al. Update for the practicing pathologist: The International Consultation On Urologic Disease-European association of urology consultation on bladder cancer. Mod Pathol. 2015;28(5):612-630. doi:10.1038/modpathol.2014.158

Dimitris Goutas (1), Andreas C. Lazaris
First Department of Pathology, School of Medicine, The National and Kapodistrian University of Athens, Greece

Prostate

prostate, bladder