Histologic and histochemical characterization of seminal vesicle intraluminal secretions: Particular emphasis on their crystalloid morphology

Archives of Pathology & Laboratory Medicine, Jan 2001 by Shah, Rajal B, Lee, Min W, Giraldo, Alvaro A, Amin, Mahul B

* Context.-We have observed intraluminal crystalloid morphology in seminal vesicles that is superficially similar to that seen in prostate neoplasia, but found little information on such morphology in the literature.

Design.-Two hundred fifty-three prostate specimens (163 needle biopsies, 75 radical prostatectomies with prostate carcinoma, 11 prostates from autopsy, and 4 cystoprostatectomies without prostate carcinoma) were examined for seminal vesicle secretions, which were categorized as (a) dense platelike inspissated, (b) fluidlike, (c) crystalloid morphology, and (d) absent. Histochemical stains (periodic acid-Schiff with and without diastase, Alcian blue at pH 2.5, and mucicarmine) were performed to characterize the nature of secretions.

Results.-Proteinaceous secretions were identified in 82% of seminal vesicles examined. Of these, 61 % had predominantly dense, platelike, inspissated secretions, 15% had predominantly fluidlike secretions, and 24% had predominantly crystalloid morphology. Although in some cases the crystalloid morphology resembled that of prostatic intraluminal crystalloids, the seminal vesicle crystalloids differed in that they were invariably multiple, had curved edges, and had varied forms (elliptical, cylindrical, rodlike, and rectangular). Seventy-one percent of seminal vesicle

crystalloids were associated with dense, platelike, inspissated secretions and appeared to be created by fracturing within platelike secretions. There was no relationship between seminal vesicle crystalloid morphology and associated malignancy in the prostate gland, as it was seen in 24% of cases with prostate carcinoma and 25% of cases without prostate carcinoma (P = 1.0000). Fluidlike secretions were positive for Alcian blue (pH 2.5) and mucicarmine, whereas dense platelike secretions and crystalloid morphology were negative for Alcian blue (pH 2.5) and mucicarmine.

Conclusions.-Seminal vesicle secretions are fairly common and, when fluidlike, are composed of acid mucopolysaccharides. Inspissation of secretions appears to be associated with loss of acidity, presumably resulting in dense platelike secretions and crystallization. Awareness of both the crystalloid morphology in seminal vesicle tissue and the distinguishing features from prostatic crystalloids may be important while interpreting prostate needle biopsies in which seminal vesicle epithelium may be confused for prostate carcinoma because of a small acinar morphology with accompanying cytologic atypia and crystalloid morphology.

(Arch Pathol Lab Med. 2001;125:141-145)

In recent years, there has been a tremendous increase in the number of prostate needle biopsies, resulting in increased detection of prostate cancer and a rising number of radical prostatectomies. Thus, surgical pathologists are increasingly examining seminal vesicle material for pathologic examination. Furthermore, in some centers transrectal ultrasound-guided biopsies are specifically targeted at the seminal vesicles in an attempt to detect seminal vesicle involvement by prostate cancer. In our routine surgical pathology practice, one of us (M.B.A.) has anecdotally noted the presence of intraluminal seminal vesicle secretions in prostate needle biopsies, which assumed a morphology superficially resembling the well-characterized prostatic intraluminal crystalloids. Since prostatic crystalloids have been associated with neoplasia of prostate and constitute a useful diagnostic feature for this tumor,1-7 misinterpretation of small acinar morphology of seminal vesicle epithelium with crystalloids as prostatic carcinoma may have diagnostic implications.

The presence of crystalloid morphology in seminal vesicles prompted us to investigate the light microscopic and histochemical characteristics of seminal vesicle secretions, which to our knowledge have not otherwise been studied in the pathology literature. The biochemical constitution of seminal vesicle secretions has been well characterized; these secretions are known to contain abundant fructose, citric acid, and other nutrient substances, as well as large quantities of prostaglandin and fibrinogen.8 The aim of the present study was to review a series of prostate needle biopsies, radical prostatectomies with prostatic adenocarcinoma, prostates from autopsy, and cystoprostatectomies without prostate carcinoma to investigate the light microscopic and histochemical characteristics of seminal vesicle secretions. Particular attention was paid to the crystalloid morphology of these secretions in order to identify distinguishing features from prostatic intraluminal crystalloids.

MATERIALS AND METHODS

A total of 253 prostate specimens, including 163 consecutive prostate needle biopsies, 75 radical prostatectomies performed for prostate cancer, 11 random autopsy cases, and 4 cystoprostatectomies without prostate cancer were retrospectively analyzed from the surgical pathology files of Henry Ford Hospital, Detroit, Mich. One case of prostate needle biopsy in which seminal vesicle epithelium contained crystalloids was retrieved from the consultation files of one of the authors (M.B.A.).