Cystic lesions of the prostate gland: an ultrasound classification with pathological correlation.

PURPOSE Cysts of prostate tissue are common. Most cases are diagnosed accidently during ultrasound but they sometimes have clinical relevance when related to lower urinary tract symptoms, infertility or the expression of neoplastic disorders. Clinical relevance is linked to the differential diagnosis of the different types of cysts. We provide an updated classification of prostate cyst disorders and indicate how these disorders appear on transrectal ultrasound based on our experience and a literature review. MATERIALS AND METHODS We retrospectively analyzed the ultrasound database and surgical specimen archives. We performed a MEDLINE(R) search of the peer reviewed literature on the diagnosis and classification of prostate cysts. RESULTS Cysts of the prostate gland can be classified into 6 categories, including 1) isolated medial cysts, 2) cysts of the ejaculatory duct, 3) simple or multiple cysts of the parenchyma, 4) complicated infectious or hemorrhagic cysts, 5) cystic tumors and 6) cysts secondary to parasitic disease. Cysts of the prostate are related to atrophy of the prostate gland as well as to other well-known factors, such as inflammatory disease, benign prostatic hyperplasia, ejaculatory duct obstruction and cancer. The differential diagnosis and diagnostic criteria are shown for each category. A possible limitation of this classification is that the quantitative aspect of the cyst was not evaluated. This is the initial step toward a more detailed classification and the basis for further pathological studies. CONCLUSIONS This comprehensive classification could be a useful tool in urological and andrological clinical practice, and for research purposes.