Stage 3 perianal extra mammary Paget's disease: A case report of a non-operative approach

INTRODUCTION AND IMPORTANCE: Extra mammary Paget's disease (EMPD) is a rare disease characterised by intraepithelial involvement of the skin by non-squamous carcinoma cells in the vulva, perineum, and scrotum. Secondary EMPD is even rarer and accounts for roughly 25% of cases (Delport, 2012) [1]. Surgery (Mohs/wide local excision) is the standard treatment for primary non-invasive disease, but management of secondary invasive EMPD is less defined as there are no current treatment guidelines. CASE PRESENTATION: A 76-year-old lady had a 1-year history of a pruritic perianal rash that was refractory to multiple topical agents. A biopsy confirmed a diagnosis of EMPD in June 2020 and on staging imaging was found to have metastatic disease in her right inguinal lymph node. Upon discussion at a multi-disciplinary team (MDT) meeting, she proceeded chemo radiation therapy followed by systemic chemotherapy as she had such extensive perianal disease that would make surgery quite morbid. She had interval imaging 3 monthly to assess response to treatment. In June 2021, the patient had a complete clinical response and has ongoing 6 monthly surveillance. CLINICAL DISCUSSION: EMPD is extremely rare and currently treatment options for secondary EMPD are still being navigated. Specifically, there are no current randomised control trials (RCTs) that compare outcomes in secondary EMPD between radiation therapy and surgery and in the context of stage III disease. This case report documents the treatment approach governed by MDT consensus and has a 1 year follow up. The case report has been reported in line with the SCARE 2020 criteria (Agha et al., 2020) [2]. CONCLUSION: The patient has had a good outcome with treatment, however ongoing surveillance is required.