A Rare Case of Co-Existing Mucin-Producing Urothelial-Type Adenocarcinoma of the Prostate and Acinar Adenocarcinoma

Abstract

Mucin-producing urothelial-type adenocarcinoma of the prostate is an extremely rare neoplasm, and its coexistence with acinar adenocarcinoma is exceptional. A 70-year-old man presented with treatment resistant symptoms of urinary obstruction. The serum prostate specific antigen (PSA) level was normal. Cystoscopy revealed a kind of “cottony fluff” in the prostatic urethra. A computed tomography (CT) scan and magnetic resonance imaging (MRI) showed a polylobulated, hyperintense lesion with mucinous content. It was located in the right lobe of the prostate and measured 35 × 27 × 35 mm. The bladder cavity did not show lesions and the gastrointestinal endoscopy was normal. Thus, the patient underwent a radical cystoprostatectomy. The histological sections showed the characteristics of a mucin-producing adenocarcinoma with extensive areas of mucin pools formation. No areas of necrosis, glandular urethritis, or carcinoma in situ were identified. Neither lymphovascular and perineural invasion nor lymph node metastases were identified. The immunohistochemical study showed diffuse positivity for keratin (KRT) 7, KRT20, and membranous beta-catenin and focal positivity for KRT34betaE12 and caudal-related homeobox gene 2 (CDX2). In addition, we identified a 10-mm focus of prostatic acinar adenocarcinoma that was positive for racemase and NKX3.1. There is no treatment algorithm for this condition; however, surgery (radical prostatectomy) with or without adjuvant chemotherapeutic treatment represents a therapeutic alternative.

Mucin‐producing urothelial‐type adenocarcinoma of the prostate with sarcomatoid features and novel molecular phenotype

“…Serum PSA values are generally less than 1.5 ng/mL, 12–14 a sign of the tumor's origin from prostatic urethral epithelium rather than prostatic luminal cells, although some patients have shown elevated serum PSA (greater than 10 ng/mL) 4,5 . Our case also showed elevated PSA with a favorable biochemical response to ADT, which is explained by co‐existing minor foci of conventional prostate adenocarcinoma demonstrating therapy‐related change, a finding that has been reported before 8 …”

“…4,5 Our case also showed elevated PSA with a favorable biochemical response to ADT, which is explained by co-existing minor foci of conventional prostate adenocarcinoma demonstrating therapy-related change, a finding that has been reported before. 8 Histologically, the tumor shows atypical, tall, pseudostratified columnar cells (likely arising from glandular metaplasia of the prostatic urethra or proximal prostatic ducts) infiltrating the stroma. Nuclear atypia and mitotic activity have been noted along with varying degrees of necrosis, signet-ring cells, squamous differentiation, perineural invasion, and granulomatous inflammatory response.…”

“… 1 Other entities in the differential diagnosis like primary prostatic adenocarcinoma with mucin production and secondary metastasis from primary bladder or colonic origin are more commonly encountered. Data on these cases are very limited, and ongoing effort via case studies provides an improved understanding of this entity 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 (Table 2 ). Most patients with this tumor present with urinary obstruction, dysuria, hematuria, and mucosuria.…”

“… 4 , 5 Our case also showed elevated PSA with a favorable biochemical response to ADT, which is explained by co‐existing minor foci of conventional prostate adenocarcinoma demonstrating therapy‐related change, a finding that has been reported before. 8 …”