Periacinar retraction clefting and d2-40 expression in prostatic adenocarcinoma.

Retraction clefting is known to appear in various types of tumors, but it has only recently been recognized as a specific histological phenomenon. Previously, it was considered merely a laboratory procedure artifact, but lately, there have been some assumptions that peritumoral retractions actually represent lymphatic spaces. In our study, we analyzed neoplastic glands in 52 specimens of prostatic adenocarcinoma. Immunohistochemical analysis was performed using D2-40 antibody, to highlight lymphatic endothelium and thereby differentiate actual lymph vessels or lymphovascular invasion from periacinar retractions. Our results showed that the number of lymph vessels was significantly lower in tumorous tissue compared to adjacent normal prostatic tissue. On the other hand, the number of lymph vessels in tumorous tissue was significantly higher than the number of lymph vessels mimicking periacinar retractions. Overall, the number of lymph vessels mimicking periacinar clefts was particularly low. These results are in accordance with our previous studies, which had shown that periacinar clefting appears due to lack of basal cells and stromal changes around tumorous acini. Also, these results support our hypothesis that retractions do not represent lymph vessels but should be considered a distinct entity, which is proven to be helpful both as diagnostic and predictive factor.