Sarcomatoid carcinoma of the prostate

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Sarcomatoid carcinoma of the prostate is a rare malignant prostatic tumor variant usually composed of both malignant glandular cells and spindle cells.

Terminology

Sarcomatoid carcinoma of the prostate is also known as carcinosarcoma, metaplastic carcinoma or spindle cell carcinoma of the prostate .

Epidemiology

It is a rare prostatic tumor with less than 100 cases reported in the literature up to 2011. Most cases are observed in the age group of 50-89 years

Associations

Apparently approximately or even more than half of the cases are detected after initial treatment of acinar adenocarcinoma of the prostate .

Clinical presentation

Similar to prostate carcinoma typical symptoms are related to voiding as poor flow, hesitancy and incomplete voiding and the associated bladder filling as dysuria, nocturia urinary urgency and frequency. Perineal or rectal pain, burning on ejaculation is less common. Constitutional symptoms such as weight loss may also occur .

Digital rectal examination (DRE) might indicate enlarged prostate nodular and hard to palpate.

A urinalysis might show microscopic or macroscopic hematuria. Prostate specific antigen (PSA) might be normal or elevated .

Complications

If left untreated sarcomatoid carcinoma of the prostate will progress as any malignancy. In addition, it might lead to urinary retention and subsequent renal failure .

Pathology

Sarcomatoid carcinoma is a biphasic malignancy featuring malignant mesenchymal sarcomatous and epithelial carcinomatous elements with a controversial origin.

Macroscopic appearance

Macroscopically sarcomatoid carcinoma of the prostate has been referred to as usually large grey-white to pink colored and otherwise non-specific mass, showing local extension into the surrounding tissues at the time of diagnosis . Similar to other prostatic tumors they might show hemorrhage or necrosis .

Microscopic appearance

Microscopic features of sarcomatoid carcinoma of the prostate are an admixture of epitheloid mostly acinar type with sarcomatous or spindle cell components featuring enlarged hyperchromatic nuclei, frequent mitoses and infrequent necrosis .

Immunohistochemistry

Epithelial elements usually express cytokeratins PSA and PSAP, sarcomatoid components are usually positive for vimentin or smooth muscle actin. Cytokeratin expression by the spindle cell component rather suggests a common origin than a collision tumor .

Radiographic features

Imaging is usually done for staging, more precisely to depict local tumor growth including extraprostatic extension, seminal vesicle invasion, infiltration of other adjacent structures and the detection of regional lymphadenopathy as well as distant metastases.

MRI

One case demonstrated a round or lobular mass. In addition, there might be signs of local tumor extension or regional lymphadenopathy .

  • T2: high signal intensity
  • T1 C+ (Gd): rim enhancement

Radiology report

The radiological report should include a description of the following :

  • tumor size and extent
  • localization within the prostate gland
  • signs of extracapsular extension
  • signs of seminal vesicle invasion
  • signs of bladder invasion
  • regional lymph node involvement

Treatment and prognosis

Due to the small number of cases no standard recommendations are available. Surgery seems to be the most effective and operable tumors are treated with resection. This includes different approaches from radical prostatectomy to pelvic exenteration depending on the tumor extent possibly along with adjuvant chemotherapy or radiotherapy .

Overall prognosis has been reported to be poor but might be much better in a local disease that is as long there the tumor is confined to the prostate and no bladder invasion or lymph node involvement is evident .

Androgen deprivation therapy seems to have no effect on tumor growth and chemotherapy seem to be ineffective in a significant number of patients .

Differential diagnosis

Conditions which can mimic the presentation and/or the appearance of sarcomatoid carcinoma of the prostate gland include: