Benign mimics of prostatic adenocarcinoma

Abstract

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.

Prostate cancer with comedonecrosis is frequently, but not exclusively, intraductal carcinoma: a need for reappraisal of grading criteria

“…), and challenging cases were reviewed in a consensus with a second specialised urological pathologist (N.S.G.). Criteria for considering a focus as intraductal carcinoma were designed similarly to those for benign mimics of prostate cancer, in that areas of cribriform glands were evaluated as a whole . If most of the glands contained a definite basal cell layer, other glands contained a patchy basal cell layer and rare glands with necrosis contained no basal cells, the area as a whole was considered intraductal carcinoma.…”

“…Criteria for considering a focus as intraductal carcinoma were designed similarly to those for benign mimics of prostate cancer, in that areas of cribriform glands were evaluated as a whole. 10,11 If most of the glands contained a definite basal cell layer, other glands contained a patchy basal cell layer and rare glands with necrosis contained no basal cells, the area as a whole was considered intraductal carcinoma. Conversely, if entire areas of cribriform cancer with comedonecrosis included no basal cells, this was interpreted as invasive cancer (Figure 1).…”

Verumontanum-Mukosahyperplasie als Differenzialdiagnose eines Lokalrezidivs nach radikaler Prostatektomie

“…Angesichts der PSA-Negativität stellte sich die Frage der Differenzialdiagnostik eines Lokalrezidivs eines entdifferenzierten Prostatakarzinoms. In der Literatur bekannte Differenzialdiagnosen sind das nephrogene Adenom, der urethrale Polyp, das Paragangliom von retroprostatischem sympatischem Gewebe und schließlich die VMGH [3]. Das extraurethrale Wachstum der Raumforderung sprach gegen einen urethralen Polyp.…”

“…Immunhistochemisch zeigte sich keine PSA-Expression, sondern eine Expression des Proteins p63 in der Basalzelllage, die bei Prostatakarzinomen nicht existiert [4]. Darüber wurde zytoplasmatisch keine Expression von AMACR (Alpha-methylacyl-CoA racemase) beobachtet, was auch gegen ein Rezidiv eines Prostata- Eine eher seltene aber dennoch bekannte Differenzialdiagnose eines Prostatakarzinoms ist das nephrogene Adenom als eine metaplastische Läsion, die durch eine Urothelverletzung überall im Urogenitalsystem auftreten kann [3]. Im Bereich der prostatischen Urethra sind in der Literatur 26 Fallberichte veröffentlicht.…”

“…Immunhistochemisch liegt in der Hälfte der Fälle eine Expression von p63 und AMACR vor, was die Abgrenzung zum Prostatakarzinom erschwert [7]. Das Paragangliom besteht aus Ansammlungen von neuroendokrinen Zellen, die sich i. d. R. außerhalb der Prostata oder neben den neurovaskulären Bündeln befinden [3]. Bei unserem Patienten konnte Letzteres histomorphologisch ausgeschlossen werden.…”