Long-Term Complete Response and Survival in Metastatic Extramammary Paget’s Disease Treated With Trastuzumab Plus Paclitaxel: A Case Report

Extramammary Paget's disease is a rare skin cancer that usually arises from the secretory cells of the apocrine glands. In most cases, an extramammary Paget's tumor occurs as a single intraepithelial form not associated with another cancer, although rarely, it may be associated with other loco-regional or distant cancer. It is generally slow-growing and diagnosed in situ. Most often, surgical excision with wide margins is curative, with the local recurrence rate being lower after the Mohs micrographic surgery technique. Nonetheless, relapses are frequent. In the metastatic setting, there are no treatment guidelines or standard therapies; additionally, the experience is limited to a few individual cases, and the efficacy of conventional chemotherapies is not well-defined. Moreover, chemotherapy can also have serious side effects; therefore, there is a need to identify more effective and less toxic therapies. In this case report, we have observed a long-lasting complete response with anti-HER2 plus paclitaxel.