Benign Mimickers of Prostate Adenocarcinoma on Needle Biopsy and Transurethral Resection

Smoking Is Associated With Basal Cell Hyperplasia on Prostate Biopsy Specimens

OBJECTIVES

To the best of our knowledge, no study has analyzed the association between cigarette smoking and prostate basal cell proliferation. Therefore, we sought to evaluate whether smoking status is associated with the presence of basal cell hyperplasia (BCH).

METHODS

We performed a retrospective analysis of 8,196 men aged 50 to 75 years with prostate-specific antigen values between 2.5 µg/mL and 10 µg/mL and prior negative biopsy who were enrolled in the (REDUCE) trial. Cigarette smoking status was divided into current, former, or never categories at enrollment. The association between smoking and baseline BCH was evaluated, with logistic regression in univariable and multivariable analysis.

RESULTS

A total of 1,233 (15.1%) men were current smokers, 3,206 (39.1%) were former smokers, and 3,575 (45.8%) were never smokers. In univariable analysis, current smoking was associated with higher baseline BCH occurrence compared with never (odds ratio [OR], 1.87; 95% confidence interval [CI], 1.14-3.10) and former smokers (OR, 1.77; 95% CI, 1.06-2.95). Similar results were found after adjusting for patient characteristics (current vs never smokers: OR, 1.92; 95% CI, 1.14-3.26; current vs former smokers: OR, 1.71; 95% CI, 1.01-2.91).

CONCLUSIONS

Among men undergoing prostate biopsy, all of whom had a negative biopsy result, current smoking at enrollment was independently associated with BCH in standard peripheral zone prostate biopsies.

Three-dimensional architecture of common benign and precancerous prostate epithelial lesions

Aims

Many glandular lesions can mimic prostate cancer microscopically, including atrophic glands, adenosis and prostatic intraepithelial neoplasia. While the characteristic histopathological and immunohistochemical features of these lesions have been well established, little is known about their three‐dimensional architecture. Our objective was to evaluate the three‐dimensional organisation of common prostate epithelial lesions.

Methods and results

500 μm‐thick punches (n = 42) were taken from radical prostatectomy specimens, and stained with antibodies targeting keratin 8–18 and keratin 5 for identification of luminal and basal cells, respectively. Tissue samples were optically cleared in benzyl alcohol:benzyl benzoate and imaged using a confocal laser scanning microscope. The three‐dimensional architecture of peripheral and transition zone glands was acinar, composed of interconnecting and blind‐ending saccular tubules. In simple atrophy, partial atrophy and post‐atrophic hyperplasia, the acinar structure was attenuated with branching blind‐ending tubules from parental tubular structures. Three‐dimensional imaging revealed a novel variant of prostate atrophy characterised by large Golgi‐like atrophic spaces parallel to the prostate surface, which were represented by thin, elongated tubular structures on haematoxylin and eosin (H&E) slides. Conversely, adenosis lacked acinar organisation, so that it closely mimicked low‐grade prostate cancer. High‐grade prostatic intraepithelial neoplasia displayed prominent papillary intraluminal protrusions but retained an acinar organisation, whereas intraductal carcinoma predominantly consisted of cribriform proliferations with either spheroid, ellipsoid or complex interconnecting lumens.

Conclusions

While various prostate epithelial lesions might mimic malignancy on H&E slides, their three‐dimensional architecture is acinar and clearly different from the tubular structure of prostate cancer, with adenosis as an exception.

Benign mimics of prostatic adenocarcinoma

Benign mimics present either as common challenges in daily routine practice or may cause diagnostic dilemmas because some are less commonly seen and one may be less familiar in recognizing them. There are a multitude of mimics of prostatic adenocarcinoma, which may represent normal gland structures, benign proliferations, atrophic lesions, hyperplastic or metaplastic changes, and inflammatory processes. Some of them are preferentially found in certain anatomic areas of the prostate, either confined to the prostate, or outside of the gland. Various benign mimics of prostatic carcinoma may be also evaluated based on their morphologic similarity to Gleason patterns 3-5 of prostatic adenocarcinoma. Most of the mimics are easily recognizable in larger specimens, such as TUR of the prostate or radical prostatectomy specimens, but they may pose diagnostic problems when the evaluation is done on limited tissue, such as needle-core biopsies or if prostate specimens are infrequently encountered in practice. Therefore, before signing out a report with a diagnosis of prostatic carcinoma, pathologists should carefully consider and rule out the various benign lesions that may mimic carcinoma. This is particularly relevant in the current prostate biopsy practice which relies on using extended biopsy core templates. The awareness and familiarity with the characteristic features of the mimics and judicial use of additional ancillary tests, including immunohistochemistry can prevent overdiagnosis and false-positive interpretation. This review provides a contemporary update on the broad spectrum of the benign prostatic lesions that can mimic prostate adenocarcinoma, outlines their key morphologic and immunohistochemical diagnostic features, and provides a diagnostic, pattern-based approach in establishing a correct diagnosis and distinguishing them reliably from prostatic adenocarcinoma.