BACKGROUND In extramammary Paget's disease, compared with patients with carcinoma in situ (CIS), patients with malignancies underlying dermis and subcutaneous tissues or lymph node metastasis appear to have a much worse prognosis.
OBJECTIVE The purpose was to examine our extramammary Paget's diseases patients in terms of pathological tumor invasion, lymph node metastasis, and prognosis and to refer to indications of lymph node dissection.
METHODS The 34 patients were divided into four groups by pathological tumor invasion: CIS, microinvasion to the papillary dermis (MIPD), invasion to the reticular dermis (IRD), and invasion to subcutaneous tissues (IST). Their age, sex ratio, follow-up periods, history of other cancers, lymph node metastasis, and prognosis were compared among the four groups and referred to indications of lymph node dissection.
RESULTS. In the groups of CIS and MIPD, all patients appeared to have no lymph node metastasis and death caused by this disease. In the groups of IRD and IST, 8 of 12 patients showed pathological lymph node metastasis, and all of them died due to metastasis of the tumor. In the cumulative survival rate of the patients according to the level of invasion, 5-year survival rate was 100% in CIS and MIPD groups, 33.3% in the IRD group, and 0% in the IST group.
CONCLUSION In the treatment of extramammary Paget's disease, indications of lymph node dissection are an important issue as well as wide local excision. From this prospective study, we have developed an algorithm for indications of lymph node dissection.