Original and infiltrating patterns of prostatic carcinoma.

In order to demonstrate the original and infiltrating patterns of prostatic carcinoma, the change of histological characteristics associated with increasing total cancer volume was investigated. Tissue specimens from 196 histopathological cases, obtained at the Kyushu Cancer Center, were reviewed in embedded whole-mount antegrade radical prostatectomy specimens with adenocarcinoma. Three groups (<0.5 cm(3), ≤0.5 cm(3) <1 cm(3) and ≥1 cm(3)) of total cancer volume were identified and a histological study on each group was conducted based on the 2005 International Society of Urological Pathology Consensus Conference on Gleason Grading of Prostatic Carcinoma. With a cancer volume of <0.5 cm(3), Gleason primary patterns 3 and 4 were observed in 64.4 and 26.7% of the tumors, respectively, while Gleason secondary patterns 3 and 4 were observed in 53.3 and 42.2%, respectively. The density of the acini was much higher in comparison with that of ambient normal acini. The percentage of acini, including cribriform carcinoma classified as Gleason pattern 3, increased significantly with the increase of cancer volume (p<0.01). The original pattern of the prostatic carcinoma was histologically composed of small acini of Gleason patterns 3 and 4 without forming a cribriform pattern. In addition, prostatic carcinoma infiltrated the surrounding stroma at a very early stage, thus infiltrating not only the stroma but also the preexisting ducts and acini, causing an increased cancer volume.