Clinicopathological characteristics, management and outcome of metastatic penoscrotal extramammary Paget's disease

Background  Metastatic penoscrotal extramammary Paget's disease (EMPD) has seldom been reported in the literature.
Objectives  To improve the knowledge of the clinicopathological characteristics, management and outcome in patients with this disease.
Methods  The medical records and pathological slides of 10 patients with metastatic EMPD and 33 patients with nonmetastatic disease were reviewed. Immunohistochemical staining for epithelial cadherin (E-cadherin) was performed in the primary skin disease. All the 10 patients received 5-fluorouracil- or docetaxel-based chemotherapy.
Results  The most common sites of metastases were lymph nodes followed by bone. Patients with metastatic EMPD were more likely to be young and had elevated carcinoembryonic antigen (CEA) levels. Dermal or deeper invasion, lymphovascular embolization and negative expression of E-cadherin were important pathological predictors of metastatic potential. In invasive EMPD, lymphovascular embolization but not expression of E-cadherin was significantly associated with the risk of metastases. In three patients, ¹⁸F-fluorodeoxyglucose positron emission tomography (PET)–computed tomography (CT) scans revealed occult lymph node metastases which were overlooked at conventional CT examinations. Two patients had complete response to the chemotherapy, three had partial response and five had progressive disease. The 2-year overall survival rate was 48% in patients with metastatic EMPD. In those patients with significantly elevated CEA level, the value of CEA paralleled the disease course.
Conclusions  Metastatic EMPD tended to have dermal invasion and lymphovascular embolization. PET–CT scans were helpful in detecting distant metastases. 5-Fluorouracil- or docetaxel based-chemotherapy was effective in some patients. Serum CEA level can be a useful biomarker for monitoring disease course.