PATHOLOGY

Precursor lesions to prostatic adenocarcinoma
Epstein JI
Departments of Pathology, Urology and Oncology, The Johns Hopkins Hospital, 401 N. Broadway St., Rm 2242, Baltimore, MD, 21231, USA
Virchows Arch. 2009; 454: 1-16

• High-grade prostatic intraepithelial neoplasia (PIN) is the one well-documented precursor to adenocarcinoma of the prostate. This review article defines both low- and high-grade PIN. Unusual variants of high-grade PIN are illustrated. Benign lesions that may be confused with high-grade PIN, including central zone histology, clear cell cribriform hyperplasia, and basal cell hyperplasia are described and illustrated. High-grade PIN is also differentiated from invasive acinar (usual) and ductal adenocarcinoma. The incidence of high-grade PIN, its relationship to carcinoma (including molecular findings), and risk of cancer on rebiopsy are covered in detail. Finally, intraductal carcinoma of the prostate, a controversial entity, is discussed and differentiated from high-grade PIN.
  
  
• Editorial Comment
  This is a nice review on precursor lesions to prostatic carcinoma. High-grade prostatic intraepithelial neoplasia (PIN) (Figure-1) was previously described by many authors using such terms as atypical epithelial proliferation, atypical glandular hyperplasia, atypical glandular proliferation, atypical hyperplasia, dysplastic lesions, dysplastic hyperplasia, cribriform hyperplasia, and atypical primary hyperplasia (1-6). These lesions were of interest for German authors and in the 80s studied by American authors. Bostwick described 3 grades for the lesion: low, intermediate and high-grade - grades 1, 2, and 3 (7). In 1989 during an international workshop in Bethesda, USA, sponsored by the American Cancer Society in an attempt to unify nomenclature it was introduced the term prostatic intraepithelial neoplasia (PIN) (8). In the same workshop it was suggested to refer in the pathology reports only to high-grade PIN (grades 2 or 3) due to the fact that low-grade PIN (grade 1) lesions have poor reproducibility among pathologists and lack any significant association with concomitant cancer.
  The presence of PIN in a biopsy means a high frequency for finding cancer in a second biopsy. This frequency varies in the literature between 26% and 53%, however, with the advent of extended biopsies this frequency today is 27%-31% (9). In a study by Herawi et al. (10) the risk of cancer on biopsy within 1 year following a diagnosis of high-grade PIN in extended biopsies was very low (13.3%). Herawi et al. concluded that for patients diagnosed with high-grade PIN on extended initial core sample, a repeat biopsy within the first year is unnecessary in the absence of other clinical indicators of cancer.

References
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Dr. Athanase Billis
Full-Professor of Pathology
State University of Campinas, Unicamp
Campinas, São Paulo, Brazil
E-mail: athanase@fcm.unicamp.br