The clinical significance of high-grade PIN — an update

A newly published mini-review in BJU International deals with the biologic and clinical significance of high-grade prostatic intraepithelial neoplasia (HG-PIN) as a sole finon an initial biopsy for risk of prostate cancer. This review would be a useful document for support group leaders and other prostate cancer educators to have on hand to share with snewly diagnosed with HG-PIN.

Montironi et al. discuss the pathologic identification of PIN and the evolution of our understanding of the significance of this finding over the past 50 years since it was first characterized by McNeal in the early 1960s. They go on to state that, as of today:

There is epidemiological, morphological and molecular evidence that HG-PIN is a precursor lesion to some carcinomas of the prostate.

They further note that, over the past few years, there has been an apparent and significant  decrease (from 36 to 22percent) in the predictive value of HG-PIN for prostate cancer after an initial diagnosis of HG-PIN. They express the view that,

A major factor contributing to the decreased incidence of [prostate cancer] after a diagnosis of HG-PIN on needle biopsy in the contemporary era is related to increased needle biopsy core sampling, which detects many associated cancers on initial biopsy.

Historically, a finding of HG-PIN on initial biopsy would lead to a repeat biopsy within a year of the initial diagnosis of HG-PIN. Montironi et al. now state that,

… because of the potential medicolegal consequences of not following up on a HG-PIN diagnosis, we believe a reasonable approach would be to perform repeat biopsy 2 – 3 years after a HG-PIN diagnosis on needle biopsy until more data is gathered. Re-biopsy should be performed in the region of the original HGPIN site and in adjacent sites, although the entire prostate should be sampled.

They also make the point that it is critically important for pathologists to distinguish carefully between a finding of HG-PIN and a finding of intraductal carcinoma, because,

The latter, even when isolated in a prostate biopsy, carries a predictive value of 100 percent for cancer in a repeat biopsy.

Finally, they note that multi-focal HG-PIN (as opposed to a single focus of HG-PIN), when identified on prostate biopsy, does come with a relatively high predictive value for cancer on a repeat biopsy.

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