CASE OF THE WEEK
2020-16 / April 20
(Contributor: Jonathan C. Slack and Asli Yilmaz)
An man in his 80s with a history of painless hematuria has a small polypoid lesion within the proximal prostatic urethra.
Quiz
1. What is the correct diagnosis?
a. Cystitis cystica and glandularis with neuroendocrine differentiation
b. Prostatic adenocarcinoma with Paneth cell-like neuroendocrine differentiation
c. Invasive urothelial carcinoma with neuroendocrine differentiation
d. Well-differentiated neuroendocrine tumor (carcinoid) of the urethra
e. Neuroendocrine carcinoma of the urethra
1. d
1. Well-differentiated neuroendocrine tumor (carcinoid) of the urethra
This case is an example of a well-differentiated neuroendocrine tumor (carcinoid) of the proximal prostatic urethra. Neuroendocrine differentiation is supported by the strong chromogranin and synaptophysin staining (Figure D; synaptophysin (insert)). Patchy positivity for GATA3, and lack of expression of prostatic markers (NKX3.1, PSA, PSAP), supports a urothelial rather than a prostatic origin. Ki-67 staining is negligible (<1% of neoplastic cells are positive). The bland morphology, abundant cytoplasm, lack of mitoses, low Ki-67 index, and absence of necrosis supports a benign diagnosis. Given that increased amounts of neuroendocrine differentiation are often observed in proliferative cystitis and the majority of bladder carcinoids have adjacent proliferative cystitis (9 of 13 cases), Chen and Epstein postulate that reactive bladder lesions could be the precursor to many bladder carcinoids.
Well-differentiated neuroendocrine tumors (carcinoids) of the prostatic urethra and bladder are thought to be benign lesions that have an excellent prognosis. Clinically, they are usually small polypoid masses in the bladder neck, trigone, or prostatic urethra that present with hematuria. They are thought to arise from isolated neuroendocrine cells from the basal layer of the urothelium. No instances of recurrence were found in the largest series of these lesions and in most cases the biopsy itself appears curative
1. Primary carcinoid tumors of the urinary bladder and prostatic urethra: a clinicopathological study of 6 cases. Chen Y, and Epstein J. Am J Surg Pathol. 2011; 35: 442-446.
Jonathan C. Slack and Asli Yilmaz,
University of Calgary,
Calgary, Alberta
Jonathan.Slack@cls.ab.ca
Prostatic Urethra
Urethra, Bladder, Neuroendocrine, Carcinoid