Publication, selected for review:
Intraductal Carcinoma of the Prostate Extreme Nuclear Size Is Not a Diagnostic Parameter (link to pdf)
Samaratunga, Hemamali MBBS, FRCPA*,†; Delahunt, Brett MD, FRCPA*,‡; Yaxley, John W. MBBS, FRACS†,§; Johannsen, Shulammite MSc*; Egevad, Lars MD, PhD
Précis: This timely article addresses the highly controversial definition of intraductal carcinoma of the prostate (IDCP). Lack of uniformly accepted diagnostic criteria makes the diagnosis particularly challenging. Presence of cells with nuclei that are 6 or more times larger than those in corresponding benign prostatic luminal cells is listed as one of the criteria for the diagnosis of IDCP with loose cribriform pattern or micropapillary architecture in the 4th ed. of WHO Classification of Tumours of the Urinary System and Male Genital Organs (2016). However, this nuclear size criterion was not validated in a formal study.
The authors performed morphometric analysis on 100 prostatectomy cases with IDCP, diagnosed on the basis of intraductal presence of acinar adenocarcinoma with cribriform, solid, or micropapillary architecture, with or without comedonecrosis. The authors found that IDCP nuclei have on average 1.3x larger diameter / 1.6x larger nuclear size than benign luminal cells. Only three patients had rare large nuclei with maximum 3.0x nuclear diameter / 3.8x nuclear area enlargement and none met the 6.0 nuclear enlargement criterion. This study does not support the validity of 6x enlargement criterion for IDCP diagnosis. And, as authors mention, relying on this criterion would lead to underreporting of IDCP.
Comment:
There are several definitions of IDCP, and the findings of this well-designed study effectively exclude the “6x nuclear size” criterion as it appears virtually non-existent. This arbitrary size criterion was likely intended to help distinguish micropapillary IDCP and loose cribriform pattern IDCP from high grade PIN and / or atypical intraductal /acinar proliferation. The authors of this study offer a thoughtful discussion on these topics well worth reading. However, the authors do not discuss how, in their opinion the nuclear parameters, such as enlargement (unclear to which point), chromatin pattern, nuclear membrane irregularity and other features of nuclear atypia should be used to distinguish IDCP from atypical intraductal proliferation (AIP) in the context of loose cribriform or micropapillary pattern. IDCP will likely remain a “hot topic” for clinico-pathological research as there are still many unanswered questions regarding its pathogenesis and molecular features.
Reviewers: Oleksandr Kravtsov and Francesca Sanguedolce, supervised by Th. Van der Kwast.