Urothelial carcinoma of the prostate

Urothelial carcinomas or transitional cell carcinomas of the prostate are malignant neoplasms that can occur as primary cancers of the prostate gland.

Epidemiology

Prostatic urothelial carcinomas account for less than 2-4% of all prostate cancers ¹ and are usually seen in middle-aged men ².

Associations

The tumors occur most commonly in close association with bladder cancer or urethral carcinoma ^1-3. 

Diagnosis

Prostatic urothelial carcinomas are mainly diagnosed based on features from histopathology and immunohistochemistry ³.

Clinical presentation

Typical symptoms include hematuria and voiding symptoms as irritation, dysuria or other obstructive symptoms ^2,3. The digital rectal examination might reveal an enlarged and/or hard prostate. Prostate-specific antigen (PSA) should not be elevated ³.

Complications

Prostatic urothelial carcinomas can metastasize to bone, lung or liver. Bony metastases are typically osteolytic.

Pathology

Location

Urothelial carcinomas of the prostate typically originate from the prostatic urethra or the prostatic ducts ³.

Microscopic appearance

Microscopically prostatic urothelial carcinomas are characterized by the following histological features ³:

• tendency to ductal growth
• solid cylinders 
• possible central comedo necrosis
• nuclear polymorphism
• frequent mitoses
• stromal invasion with cords nests and desmoplastic response

Immunophenotype

Urothelial carcinomas of the prostate express urothelial cell markers as GATA3, CK7 or P63 on immunohistochemistry stains. They should be negative for prostatic cell markers as prostatic-specific antigen or NKX3-1 ^2,3.

Radiographic features

MRI

Urothelial carcinomas have been described as infiltrative but otherwise uncharacteristic ³. 

Signal characteristics

• T2: mildly hyperintense
• DWI: heterogeneously hyperintense on high b-value with moderate low signal intensity on ADC
• DCE (Gd): avid enhancement 

Radiology report

The radiological report should include a description of the following features:

• form, location and size
• tumor margins
• bladder or urethral invasion
• suspicious or enlarged lymph nodes
• any concomitant prostate cancer

Treatment and prognosis

Their prognosis is good as long as they occur in isolation as carcinoma in situ ³. If they occur in association with transitional carcinomas of the bladder or urethra their prognosis is poor with an estimated 5-year survival of 35-40% ³. Management strategy is usually multimodal and includes surgery including cystoprostatectomy as well as adjuvant radiotherapy and chemotherapy ³. 

Transurethral resection and instillation of Bacillus Calmette-Guérin (BCG) can be performed in carcinoma in situ ⁴. 

History and etymology

Urothelial carcinomas of the prostate were first described by Norman Ende et. al in 1963 ^2,4.

Differential diagnosis

Conditions mimicking the clinical presentation or imaging appearance of prostatic urothelial carcinoma include ¹:

• invasive prostate adenocarcinoma
• urethral polyp
• neuroendocrine tumors of the prostate
• mesenchymal tumors of the prostate