Basal cell carcinoma of the prostate

Last revised by Dr Joachim Feger on 11 Feb 2022

Basal cell carcinoma of the prostate or prostatic adenoid basal proliferation of uncertain significance is a type of prostate cancer resembling adenoid cystic carcinoma of the salivary glands.

Other terms include 'adenoid cystic carcinoma', 'adenoid basal cell tumor', 'adenoid cystic-like tumor' etc 1.

Basal cell carcinoma of the prostate is very rare 1 and occur in a wide age range 2,3.

The diagnosis of basal cell carcinoma of the prostate is established by typical histological features.

Typical symptoms include voiding symptoms such as dysuria, nocturia, urgency other obstructive symptoms and/or enlarged or hard prostate in digital rectal examination 3,4. Prostate-specific antigen (PSA) might be normal or slightly elevated 2-4.

Basal cell carcinomas are malignant tumors arising from basal cells. Criteria differentiating them from basal cell hyperplasia are not well-defined and include extensive infiltration between the glandular components,  perineural invasion extraprostatic extension or necrosis 1-3.

Basal cell carcinomas are not assigned a Gleason grade 1-3.

Macroscopically tumors have been described as solid with a white and microcystic appearance 1,3.

Microscopically basal cell carcinomas of the prostate have been characterized by different growth patterns 1-4:

  • pleomorphic nuclei and scant cytoplasm
  • small solid nests with peripheral palisading
  • cribriform spaces
  • adenoid basal cell hyperplasia-like pattern
  • large and solid nests with or without necrosis

Other histological features include the following:

  • infiltrative permeative growth
  • perineural invasion
  • desmoplastic or myxoid stroma
  • sparse or absent mitoses

Proliferative markers as Ki67 might help in the differentiation from basal cell hyperplasia 1,2. Other immunohistochemistry stains that might be positive include BCL-2, p63 and/or cytokeratin 34βE12 3,4.

Prostatic markers as the prostate-specific antigen (PSA) and prostate acid phosphatase (PAP) should be negative in the absence of concomitant prostate adenocarcinoma 1.  

Rearrangement of the MYB gene has been found in a subset of basal cell carcinomas 3.

Only a few imaging descriptions can be found in the literature MRI of the prostate might show an infiltrative but otherwise uncharacteristic tumor possibly with extraprostatic extension, seminal vesicle invasion or invasion of the bladder wall if extensive 4,5 or might not show any obvious findings 6.

Possible signal characteristics include:

  • T2: low to intermediate signal intensity
  • DWI: diffusion restriction (hyperintense on high b-value and hypointense on ADC map)
  • DCE (Gd): early enhancement

The radiological report should include a description of the following:

Probably in part due to its rarity and its exact behavior there is no real consensus on the optimal treatment. Radical prostatectomy seems to be most commonly accepted, radiation therapy and chemotherapy are other options 4. The tumor can locally recur and metastasize especially at higher stages 1,4.

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

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