Primary mucin-producing urothelial-type adenocarcinoma of the prostatic urethra diagnosed on TURP: a case report and review of literature

Abstract

Background: Mucin-producing urothelial-type adenocarcinoma of the prostatic urethra is extremely rare. These lesions must be differentiated from other mucinous tumors including mucin-producing prostatic adenocarcinoma and metastases from either colonic or bladder primaries.

Case presentation: We report here a case of urothelial-type adenocarcinoma arising from the prostatic urethra. The patient is an 81 year-old man with a history of pT1 urothelial cell carcinoma of the bladder status post trans-urethral resection of bladder tumor (TURBT) who initially presented with irritative lower urinary tract symptoms and mucosuria refractory to Flomax and finasteride. A shared decision was made for the patient to undergo trans-urethral resection of prostate (TURP). At the time of surgery, a papillary tumor emanating from the prostatic urethra was found and no urothelial lesions were noted in the bladder. Pathology of the resected prostatic chips revealed an invasive adenocarcinoma with intestinal-type differentiation that stained positive for CK7, CK20, and villin, but negative for PSA, PSAP, uroplakin, and CDX-2. Colonoscopy was normal and CT scan did not show any evidence of colonic lesions nor visceral or lymph node metastases. Thus, the patient was diagnosed with a primary urothelial-type adenocarcinoma of the prostatic urethra.

Conclusion: Herein we review the literature regarding this unusual entity, and discuss the differential diagnosis, immunohistochemistry, and the importance of correctly identifying this rare tumor.

Figure 1

pT1 urothelial cell carcinoma. Patient’s original biopsy showing high grade papillary urothelial carcinoma of the bladder. Hematoxylin-eosin stain. (a) 40x magnification. (b) 100× magnification.

Figure 2

TURP prostate chip specimen. Hematoxylin-eosin stain. (a) 10× magnification, arrow demonstrates adenocarcinoma of the prostate with complex glandular arrangement. (b) 40× magnification, adenocarcinoma (*) at the edge of the TURP fragments which contrasts with nearby benign prostatic glands (**). (c) 400× magnification, demonstrating extensive intestinal differentiation. (d) 40× magnification, adenocarcinoma with extensive mucin (M) dissecting into the prostatic stroma.

Figure 3

Surgical specimen and positive pathological staining. (a) Diffusely positive staining for CK20. (b) Diffusely positive staining for CK7. (c) Diffusely positive staining for villin. (d) Mostly cytoplasmic positive staining for beta-catenin.

Figure 4

Surgical specimen and negative pathological staining. Diffusely negative staining for PSA.