Ductal adenocarcinomas of the prostate or prostatic ductal adenocarcinomas are malignant glandular neoplasms of the prostate and tend to be more aggressive than acinar adenocarcinomas.
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Terminology
Due to its morphologic resemblance, it has been formerly referred to as 'endometrial' or 'endometrioid carcinoma' of the prostate.
Epidemiology
Ductal adenocarcinomas of the prostate are the second most common malignant tumors of the prostate gland after acinar adenocarcinomas. They make up for about 3-5 % of prostate cancers 1,2 as mixed ductal-acinar adenocarcinomas and are (≤1%) in isolation 2-4.
Associations
Ductal adenocarcinomas of the prostate most frequently occur as mixed ductal-acinar adenocarcinomas 2.
Diagnosis
The diagnosis of prostatic ductal carcinomas is established with typical histological features.
Clinical presentation
Due to their location, they often present with hematuria or voiding symptoms. More peripherally located ductal adenocarcinomas often present like acinar adenocarcinomas with elevated serum prostate-specific antigen (PSA) levels, which tend to be lower than in acinar adenocarcinoma, however, 1.
Complications
Ductal adenocarcinomas of the prostate can metastasize into the penis, testis, lung, or brain 1,3.
Pathology
Ductal adenocarcinomas of the prostate are a histological subtype characterized by large cancerous glands coated with columnar epithelial cells with rich cytoplasm and stratified nuclei 2-4.
Ductal adenocarcinomas often present with high Gleason grades, in particular, if they are cribriform or solid or if necrosis is present 2,4.
Location
Ductal adenocarcinomas of the prostate are frequently located in the peripheral zone if they are mixed with acinar adenocarcinoma. In their pure form, they might be found in the periurethral area arising from the central periurethral ducts possibly protruding into the urethra 1,2.
Macroscopic appearance
Macroscopically ductal adenocarcinomas of the prostate are similar to acinar adenocarcinoma if located peripherally; if they arise from the verumontanum, they often present as exophytic polypoid or villous masses 1.
Microscopic appearance
Histologic features of prostatic ductal adenocarcinomas include the following 1-5:
cribriform, papillary or solid growth pattern
elongated pseudostratified nuclei, large nucleoli
amphophilic and occasionally clear cytoplasm
coarse chromatin
intraluminal necrotic debris
frequently stromal desmoplastic reaction with hemorrhagic inflammation
possibly perineural invasion
Immunophenotype
Immunohistochemistry stains are usually positive for prostate-specific markers as prostate-specific antigen prostate-specific (PSA), NKX3.1 2, prostate-specific membrane antigen (PSMA) or prostate-specific acid phosphatase (PAP) 6. Basal cell markers are positive in up to 30% 2.
Genetics
Fusions of TMPRSS2 and ERG genes are only seen in 10-15% of the cases 1. Ductal adenocarcinoma cells often show deletions of chromosome 6q15 or the MAP3K7 gene.
Radiographic features
Ductal adenocarcinoma is mainly diagnosed on pathological grounds. Nevertheless, reports have described it as heterogeneous, and cystic components have also been described 6.
MRI
Multiparametric MRI can aid in the detection of prostate cancer. Evaluation and reporting should be done using a likelihood score as the PI-RADS system, which deploys different criteria for peripheral and transition zones that are explained in the respective article.
Typical features include the following:
T1: isointense
T2: hypointense focus, erased charcoal sign
DWI: marked diffusion restriction (hyperintense on high b-value and hypointense on ADC map)
DCE (Gd): focal early enhancement
Radiology report
The radiological report should include a description of the following features:
form, location and size
tumor margins
extraprostatic extension
seminal vesicle invasion
bladder or rectal invasion
suspicious or enlarged lymph nodes
Treatment and prognosis
Ductal adenocarcinoma is supposed to be more aggressive than acinar adenocarcinoma 7.
However, treatment recommendations are not different. Like with acinar adenocarcinoma of the prostate, it is usually dependent on tumor stage and patient preference and includes radical prostatectomy, intensity-modulated or conventional external beam radiotherapy if the first is not possible or available. In addition, the patient might receive androgen deprivation therapy (ADT), and combinations with brachytherapy as well as chemotherapy with docetaxel might be considered.
History and etymology
Ductal adenocarcinomas of the prostate were first described by MM Melicow and MR Pachter in 1967 8.
Differential diagnosis
Ductal adenocarcinoma of the prostate is one subgroup of prostate cancer. The differential diagnosis includes the following conditions 2-4:
urethral polyp
colorectal carcinoma involving prostate
neuroendocrine tumors of the prostate
mesenchymal tumors of the prostate