Older Male with an Elevated Serum PSA

Specimen Type:

Prostate

History:

A 54-year-old male with an elevated serum PSA underwent prostate needle biopsies.

Pathologic Features:

At low magnification, infiltrating glands are seen throughout the multiple biopsy cores. Focally, sheets of squamous cells with intercellular bridges and keratin pearls are intimately associated with the infiltrating glands (Fig 1, 2). The glands display marked architectural distortion, including variation in size, shape, and spacing, and are lined by cells with enlarged hyperchromatic nuclei and prominent nucleoli (Fig 3, 4, 5, 6). The squamous cells display no significant cytologic atypia (Fig 3, 4, 5, 6).

Differential Diagnosis:

  • Adenosquamous carcinoma 
  • Adenocarcinoma with squamous metaplasia

Adenosquamous carcinoma: Adenosquamous cell carcinoma refers to the combination of squamous cell carcinoma and typical acinar carcinoma. It is uncommon in the prostate, often but not necessarily arising in the setting of prior hormone or radiation therapy, and is associated with a poor prognosis. While the adenocarcinoma component is typically high grade, the squamous component has a wide range of differentiation (references 1, 2).

Adenocarcinoma with squamous metaplasia: In addition to typical acinar adenocarcinoma, benign squamous epithelial component (metaplasia) is present, which may arise in the setting of prior hormone or radiation therapy (references).

Diagnosis:

Adenocarcinoma, with squamous metaplasia within cancer

Comment: Squamous metaplasia is not unusual in the prostate, it can occur as a result of inflammation, infarction, radiation therapy and hormonal therapy (references 3, 4). However, its occurrence that is so extensive and intimately admixed with prostate adenocarcinoma as seen in this case, is extremely rare and it has not been reported in the literature to our knowledge. Adenosquamous carcinoma is another rare entity in the prostate showing the admixture of adenocarcinoma and squamous carcinoma. The distinction of adenocarcinoma with squamous metaplasia from adenocarcinoma with squamous differentiation can be easily made by the recognition of benign-looking squamous cells in the former one.

References:

  1. Egilmez T, et al. Adenosquamous carcinoma of the prostate. Int J Urol. 2005 Mar;12 (3):319-21.
  2. Parwani AV, et al. Prostate carcinoma with squamous differentiation: an analysis of 33 cases. Am J Surg Pathol. 2004 May;28 (5):651-7.
  3. Bostwick DG, Egbert BM, Fajardo LF. Radiation injury of the normal and neoplastic prostate. Am J Surg Pathol. 1982 Sep;6 (6):541-51.
  4. Van de Voorde WM, et al. Morphologic and immunohistochemical changes in prostate cancer after preoperative hormonal therapy. A comparative study of radical prostatectomies. Cancer. 1994 Dec 15;74 (12):3164-75.