Intraductal carcinoma of the prostate: the whole story.

Intraductal carcinoma of the prostate (IDC-P) is characterised by proliferation of malignant secretory cells that markedly expand prostatic ducts and acini. Its morphological features and diagnostic criteria have been refined in recent studies. Its molecular characteristics have also been increasingly elucidated. IDC-P is strongly associated with high grade and high volume invasive prostate cancer and unfavourable clinical outcomes. Therefore, it is critical to recognise and report IDC-P, especially in prostate biopsies where the clinical implications of the diagnosis are greatest. IDC-P has to be distinguished from several other prostate lesions with similar histological appearance. The distinction between IDC-P and high grade prostatic intraepithelial neoplasia is most important as they have drastically different implications for patient management. IDC-P is an uncommon finding in prostate biopsies, and is even rarer as an isolated finding without concomitant prostate cancer in biopsies. However, patients with isolated IDC-P in biopsies are recommended for either definitive treatment or immediate repeat biopsy. This article will review the historical aspect, diagnostic criteria, molecular genetics, and clinical significance of IDC-P.