Diagnosis of Carcinoid-like Metastatic Prostatic Carcinoma by an Immunoperoxidase Method

Abstract

An unusual case of carcinoma of the prostate with metastases is described. the prostate and the metastases showed adenocarcinoma with carcinoid-like areas. A tumor with the same histologic features was found at the tip of the appendix and proved to be metastatic. The possibility of primary carcinoid of the prostate was considered; however, Fontana-Masson stain and electron microscopy failed to confirm this. Immunoperoxidase stain for prostatic acid phosphatase was done on the prostate and metastases. This stain is specific for tissues of prostatic origin. The stain was positive in the carcinoid-like areas, indicating that it was not a true carcinoid but rather prostatic carcinoma with a carcinoid-like pattern. Apparently, this is the first case of a metastatic prostatic carcinoma showing carcinoid-like areas that were positive for prostatic acid phosphatase.

Immunohistochemical Diagnosis of the Metastasizing Prostatic Carcinoma

“…Ansari et al [1] described carcinoid-like métastasés which they were able to identify as originating from a prostatic carcinoma on the basis of PAP demonstration. Ordonez et al [ 17] reported using the PAP test as an aid in distinguishing between a purely epithelial prostatic carcinoma with sarcomatous changes and carcinosar coma of the prostate, the mesenchymal portion of which is negative for PAP.…”

A novel hybridoma antibody (PASE/4LJ) to human prostatic acid phosphatase suitable for immunohistochemistry

“…The proportion of gastrointestinal carcinoids positive for PAP appears to be maximal distally (Sobin et al, 1986), and the positivity of rectal carcinoids may be a problem if the antibody is to be used for the differential diagnosis of tumours involving the wall of the rectum with no apparent mucosal origin. Positive staining for both prostatic acid phosphatase and prostate specific antigen have been reported in 'carcinoid-like' tumours of the prostate which are argyrophilic, but lack other markers of neurendocrine differentiation (Ansari et al, 1981;Almagro et al, 1986). Dispute as to whether or not these should be considered 'true' carcinoids remains.…”

Changes in immunohistochemical staining in prostatic adenocarcinoma following diethylstilbestrol therapy

“…The value of these markers in identifying the primary tumor site in metastatic disease has been clearly demonstrated [ll-141. This becomes particularly useful in unusual sites of spread and uncommon morphological patterns [18,19]. For the most part, these studies have considered the importance of demonstration of the origin where the primary site is unknown; however, in patients with known carcinoma of the prostate, it may be essential to prove that metastases originate from this site and not from a second primary.…”