Prostatic Intraepithelial Neoplasia (PIN)

*It has been reported that the total volume of HGPIN increases with increasing pathologic stage with a  significant correlation between volume of HGPIN and the number of lymph node metastases.(1)

*HGPIN by itself does not appear to elevate serum PSA levels.(1)

*The distinction between low and high grade PIN is based on the degree of architectural complexity and more importantly, on the extent of cytologic abnormalities. In low grade PIN, there is proliferation and "piling
up" of secretory cells of the lining epithelium with irregular spacing. Some nuclei have small, usually inconspicuous nucleoli while a few may contain more prominent nucleoli. (1)

*High grade PIN is characterized by a more uniform morphologic alteration.Cytologically, the acini and ducts are lined by malignant cells with a variety of architectural complexity and patterns.The individual cells are almost uniformly enlarged with increased nuclear/cytoplasmic ratio, therefore showing less variation in nuclear size than that seen in low grade PIN. Many cells of HGPIN contain prominent nucleoli and most show coarse clumping of the chromatin that is often present along the nuclear membrane.(1)

*Four patterns of HGPIN have been described, which are ;
- flat: atypia without significant architectural changes
- tufting: nuclei become  more piled up, resulting in undulating  mounds of cells
- micropapillary: columns of atypical epithelium that typically  lack fibrovascular cores
- cribrifrom: more complex architectural  patterns appear such as Roman bridge and cribriform formation (1)

*Despite alL this Evidence , we dont know the natural history of PIN, and in particular how often it progresses to cancer. Thus,unlıke in cancer of the cervix, the term "Carcinoma in situ" is not used for PIN. 

for slides ; http://www.surgicalpathologyatlas.com/glfusion/mediagallery/media.php?f=0&sort=0&s=20080802171141419


(1) WHO- Pathology and Genetics of Tumours of the Urinary System and Male Genital Organs