Intraductal carcinoma of the prostate: A comprehensive and updated review

Intraductal carcinoma of the prostate is characterized by prostatic carcinoma cells growing within ducts and/or acini. These tumors are usually associated with a high‐grade Gleason score, large tumor volume and advanced stage. Intraductal carcinoma of the prostate is also a well‐known adverse independent prognostic factor regardless of treatment. Recent studies have shown that intraductal carcinoma of the prostate is a distinctive disease entity that is different from invasive prostate carcinoma, which is generally invasive. Although the Gleason score does not consider intraductal carcinoma of the prostate, some cribriform prostate carcinomas graded as pattern 4 could be considered as intraductal carcinomas. The definition of intraductal carcinoma of the prostate is not unified, because it can occur with or without invasive prostate carcinoma. Furthermore, diagnosis of intraductal carcinoma of the prostate without invasive prostate carcinoma by needle biopsy is crucial, but is a rare event. Differential diagnosis of intraductal carcinoma of the prostate includes several pathologies. This is especially true for high‐grade prostatic intraepithelial neoplasia, although its distinction is not always straightforward. The present review discusses the concept of intraductal carcinoma of the prostate, and also describes its morphological characteristics, molecular features and clinical outcome. Given the current state of knowledge, the presence of intraductal carcinoma of the prostate should be evaluated and documented correctly in both radical prostatectomy and needle biopsy, and the clinical implications should be taken into consideration during treatment and follow up.