2020-35 / August 31
(Contributor: Daniel Athanazio)

A 66-year old patient underwent 12-core prostate biopsy.


1. What is the correct diagnosis?

a. Xanthoma with signet ring morphology

b. Acinar adenocarcinoma Gleason 5+5 (GG5)

c. Nephrogenic adenoma with signet ring morphology

d. Mucinous metaplasia of benign prostate glands

e. Acinar adenocarcinoma Gleason 3+3 (GG1) with collagenous micronodules

1. Xanthoma with signet ring morphology

Xanthoma in the prostate is a well-recognized mimicker of high grade prostatic acinar adenocarcinoma. In some instances, it may resemble an infiltrative pattern of single cells with signet ring morphology. Foamy histiocytes are usually located within the prostatic stroma, however, these cells may be seen within prostate glands and this may distort the architecture of acini and, therefore, may simulate a high-grade tumor.

In this case, the cocktail immunostains (p63 and 34be12) highlighted basal cell in the benign appearing glands. These markers were, however, negative in the infiltrative single cells. CD68 proved these cells were histiocytes both in stroma and within glands. Cells with signet ring morphology did not stain for PSA. Indeed, figures 4 and 5 show that within the preexisting glands, areas where CD68 was positive did not stain for PSA. This suggests that these are foamy histiocytes infiltrating benign glands.

Srigley JR. Benign mimickers of prostatic adenocarcinoma. Mod Pathol. 2004;17(3):328-348.

Trpkov K. Benign mimics of prostatic adenocarcinoma. Mod Pathol. 2018;31(S1):S22-S46.

Daniel Athanazio
Imagepat, Laboratory of Pathology
Salvador, Bahia, Brazil


Prostate; Prostate Neoplasms; Xanthoma