The primary objective will be to estimate the anti-tumor activity of trastuzumab by evaluating the response to trastuzumab therapy in patients with recurrent or persistent vulvar Paget's disease demonstrating HER2/neu overexpression by immunohistochemistry and/ or FISH ((fluorescence in situ hybridization).~The secondary objectives:~To evaluate the quality of life, based on the severity of the patients' vulvar itching on a 4-point verbal rating scale from 0 to 3 (0=no itching, 1=mild itching/ bothersome, 2=moderate itching/ troublesome, 3=severe itching/ extremely troublesome) as well as on the severity of the patients' vulvar pain on a numeric pain scale from 0-10 (0=no pain, 1-3=mild pain, 4-6=moderate pain, 7-10=severe pain).~To assess the frequency and severity of observed adverse effects~To assess the frequency/ incidence of HER2 in Paget's disease of the vulva
This is a phase II open-label study of the activity and safety of trastuzumab in patients with vulvar Paget's disease with overexpression of HER2 on biopsy.