Case of the Week

2020-36 / September 7

Contributors: Maiara Ferreira de Souza, Diogo Diniz, Daniel Athanazio

A male patient in his 70s underwent prostatectomy 3 months after 12-core prostate biopsy with the diagnosis of acinar adenocarcinoma Gleason 3+4 (Grade Group 2) in one biopsy site. The images are from the prostatectomy specimen.

Click on the below thumbnails to enlarge photos.

Quiz

1. What is the correct grading?

a. Gleason 3 + 3 (Grade Group 1)

b. Gleason 3 + 4 (Grade Group 2)

c. Gleason 4 + 3 (Grade Group 3)

d. Gleason 3 + 5 (Grade Group 4)

e. Gleason 5 + 4 (Grade Group 5)

Malakoplakia is a rare form of chronic inflammation characterized by solid and often extensive aggregates of foamy or eosinophilic epithelioid histiocytes. Figures 1,3 and 4 shows the transition of a small (unifocal) acinar adenocarcinoma to a solid area of malakoplakia. Figure 2 details areas of well differentiated (Gleason pattern 3) and poorly differentiated glands (Gleason pattern 4) from the acinar adenocarcinoma focus. Figure 5 shows PAS stain that enhances the cytoplasmatic inclusions in the solid lesion (while negative in the adenocarcinoma) and von Kossa stain highlighting Michaelis-Gutmann bodies with iron and calcium contents. Note that these inclusions could be readily recognized in the solid area of figure 4 (H&E stain).

Malakoplakia is a well-known mimicker of high grade (Gleason pattern 5) adenocarcinoma. In this case, proper recognition of this lesion avoided overgrading. The prostatectomy specimen confirmed the findings of a unifocal GG2 tumor from the needle biopsy. Since no inflammation or histiocytic lesion was seen in the biopsy samples, we may speculate that malakoplakia in this case could correspond to a complication secondary to infection after the biopsy procedure, as it has been described in rare cases in literature.

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.

Medlicott S, Magi-Galluzzi C, Jimenez RE, Trpkov K. Malakoplakia associated with prostatic adenocarcinoma: Report of 4 cases and literature review. Ann Diagn Pathol. 2016;22:33-37.

Guner G, Akdogan B, Baydar DE. Malakoplakia of prostate as a complication of transrectal needle biopsy. Can J Urol. 2012;19(1):6124-6127.

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The Genitourinary Pathology Society (GUPS) was formed with the vision of advancing the care of patients with urologic diseases through enhancements of best practices, research, and education in the subspecialty of Urological Pathology.

GUPS is an official Companion Society of the United States and Canadian Academy of Pathology (USCAP).

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