Prostatic intraepithelial neoplasia: an overview

Abstract

Prostatic intraepithelial neoplasia (PIN) is the most established precursor of prostatic carcinoma. The presence of prominent nucleoli within an existing duct structure is an easy way to identify the disorder. Four main patterns of high-grade PIN (HGPIN) have been described: tufting, micropapillary, cribriform, and flat. In addition to exhibiting similar cytologic features, both HGPIN and prostatic carcinoma are associated with increased incidence and severity with age, and with high rates of occurrence in the peripheral zone of the prostate. HGPIN and prostate cancer share genetic and molecular markers as well, with PIN representing an intermediate stage between benign epithelium and invasive malignant carcinoma. The clinical significance of HGPIN is that it identifies patients at risk for malignancy. With the increased use of extended biopsy protocols, clinicians are more likely to identify HGPIN and less likely to miss concurrent carcinoma. Androgen deprivation therapy decreases the prevalence and extent of PIN, and may play a role in chemoprevention. Preliminary studies suggest that selective estrogen receptor modulators may also prevent the progression of HGPIN to prostate cancer.

Figure 1

High-grade prostatic intraepithelial neoplasia: tufting pattern (hematoxylin and eosin, × 400).

Figure 2

High-grade prostatic intraepithelial neoplasia: micropapillary pattern (hematoxylin and eosin, × 400).

Figure 3

High-grade prostatic intraepithelial neoplasia: cribriform pattern (hematoxylin and eosin, × 200).

Figure 4

High-grade prostatic intraepithelial neoplasia: flat pattern (hematoxylin and eosin, × 200).

Figure 5

Representative diagrams of prostate cancer and high-grade prostatic intraepithelial neoplasia (HGPIN) in early 1990s (A) and late 1990s (B). “P” represents HGPIN. Historically when PIN was found on initial biopsy, repeat biopsy would frequently identify “missed” cancer. Given the size of the lesion, in most contemporary cases, the cancer may more frequently be missed. Figure courtesy of Wael Sakr, MD.

Figure 6

Historical biopsy approaches (left) could easily miss invasive cancer (blue) because of undersampling. In modern biopsy approaches (right), with multiple cores being taken, it is unlikely that a concomitant carcinoma in the face of prostatic intraepithelial neoplasia (yellow) will be missed. Reprinted with permission from Bostwick D et al.