Extramammary Paget disease (EMPD) is an intraepithelial adenocarcinoma characterized by epithelial infiltration of large atypical cells with prominent nuclei.1 The disease process is hypothesized to originate in the apocrine sweat glands in the anogenital region. It is often diagnosed in postmenopausal women and most commonly affects the vulva, perianal skin, and axilla but can sometimes be associated with invasive visceral or adnexal adenocarcinoma.2

Standard therapy for EMPD is wide local excision. However, many of the elderly patients affected by EMPD may be medically unfit for aggressive surgery. Radiotherapy is rarely used, and there is a paucity of reports detailing the efficacy of electron beam radiotherapy for exceptionally large EMPD lesions.