Risk stratification in extramammary Paget disease.

Extramammary Paget disease (EMPD) is an uncommon intraepithelial adenocarcinoma that involves body sites with apocrine glands such as the genital, perineal and perianal regions. Risk stratification and treatment planning for EMPD can be challenging. This review presents important prognostic information in EMPD to assist physicians with risk stratification of patients with EMPD. The best-understood prognostic factors are depth of invasion and involvement of extracutaneous sites. Tumours that invade into the reticular dermis or have a depth of > 1 mm are associated with poorer prognosis. Additionally, tumours spreading outside the skin into lymph nodes or other tissues are higher risk. There is an emerging understanding of the importance of tumour genetics in risk stratification, and we review the data on Ki-67, cyclin D1, Mucin 5AC and E-cadherin. There is less evidence supporting the importance of lesion site and patient age in risk stratification. This succinct review will be helpful in clinical practice and in EMPD research.