Seminal vesicle amyloidosis does not provide any protection from invasion by prostate cancer

To determine whether seminal vesicle amyloidosis (SVA, an unusual finding in prostatectomy specimens, with deposits usually localized and asymptomatic) affects the extension of prostate cancer into the SVs.

We identified 73 cases of localized SVA from 6575 prostatectomy specimens, that were removed because of clinically localized prostate cancer. All cases were confirmed by Congo red staining and polarization microscopy. The mean thickness of the amyloid band was measured in each case and correlated with clinicopathological characteristics. The frequency of SV involvement by prostate cancer in the presence of amyloid was compared with the percentage of pT3b classifications in the absence of amyloid.

The mean (range) age of the patients with localized SVAs was 64.4 (52-73) years. The mean thickness of the amyloid band did not correlate with patient age, preoperative prostate-specific antigen levels, the weight of the prostates, or the Gleason score and T category of the prostate cancers. In the SVA group, seven cancers invaded the SVs (9.6%), which was not significantly different from the percentage of SV involvement by cancer in total sample (9.2%, P = 0.932).

The pathogenesis of localized SVA remains poorly understood, but SVA does not seem to provide an absolute or relative protection from SV involvement by prostate cancer.