prostatic adenosquamous carcinoma

Definition : Approximately 50% of adenosquamous carcinomas may arise in prostate cancer patients subsequent to endocrine therapy or radiotherapy.

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Adenosquamous carcinomas are probably localized more commonly in the transition zone of the prostate accounting for their more frequent detection in transurethral resection specimens.

Adenosquamous carcinomas may be detected by increased serum PSA, but more typically by obstruction of the urinary outflow, requiring transurethral resection.

Patients may also present with metastatic disease. A proportion of cases show an initial response to hormone therapy.

The incidence is @<@1% of all prostatic carcinomas. The incidence will depend on how the patient population was treated, as many carcinomas in the prostate with squamous differentiation arise after radiation or hormonal therapy.

The time course for the appearance of squamous differentiation in the carcinoma varies from 3 months to many years (up to 9) after therapy.

The incidence of adenosquamous carcinoma is lower than that of pure squamous cell carcinoma.

In addition to admixture with adenocarcinoma, a few patients have had prostatic squamous cell carcinomas mixed with urothelial carcinoma and adenocarcinoma94 and urothelial carcinoma.

Grossly, the tumours are usually large, measuring up to 65 mm in greatest dimension and often replacing a substantial portion of the prostate.

Cut surfaces reveal a solid, firm, whitish-yellow, white–grey to grey–tan mass.

Central extension, with compression of the prostatic urethra, and local invasion into the bladder, rectum and seminal vesicle, was macroscopically apparent in several cases.

Microscopically, pure squamous cell carcinoma is typified by infiltrating nests, strands, and sheets of polygonal cells with nuclear atypia, with squamous differentiation manifested as individual cell keratinization, intercellular bridges, and/or keratin pearl formation. In examples of adenosquamous carcinoma, glandular and squamous components can be distinct or can exhibit direct transitions.

The application of a three-tiered grading scheme with well-differentiated, moderately differentiated or poorly differentiated categories to squamous cell carcinomas of the prostate is preferable. The Gleason grading scheme can be used for the glandular component (as long as there is no history of hormonal therapy), but not for the squamous component, of adenosquamous carcinomas. The adenocarcinoma element is often high-grade, whereas the grade of the squamous portion is variable.

Prostatic squamous cell carcinoma and adenosquamous carcinoma, like glandular adenocarcinomas, can spread along nerves, extend locally into periprostatic soft tissue, the urinary bladder and the seminal vesicles, and metastasize to lymph nodes and bone. In bone, however, the metastases are routinely osteolytic rather than osteoblastic.

In widely disseminated disease, metastatic deposits have been detected in the glans penis, peritoneum, diaphragm, liver, and lung. Special studies are of limited use in diagnosis.

The malignant squamous cells are most often negative for PSA and PSAP immunostains, and this correlates with the normal serum PSA and PSAP levels found in the vast majority of prostatic squamous cell carcinoma patients.

The mean survival for prostatic squamous cell carcinoma is not long, at 6–24 months.

See also

 adenosquamous carcinoma

References

 Histological variants of prostatic carcinoma and their significance. Humphrey PA. Histopathology. 2012 Jan;60(1):59-74. PMID: 22212078