Unlike most other cutaneous neoplasms, extramammary Paget disease (EMPD) manifests as a chronic erythematous patch. In this resident takeover, Dr. Daniel Mazori talks to Dr. Mohammed Dany about the diagnosis of primary vs secondary EMPD and the importance of screening patients for metastasis or other underlying malignancies. They also discuss the pathogenesis of EMPD and highlight future treatment targets. “The best studies that show potential are the studies focusing on PD-1 [programmed cell death receptor 1] pathway, or the checkpoint pathway. I think there is a lot of potential with immunotherapy for EMPD,” Dr. Dany explains. *  *  * This week in dermatology news: * Americans getting more sunburns (https://bit.ly/33iNOD1) * Nine states have no board-certified pediatric dermatologist, analysis reveals (https://bit.ly/3faY5Do)  * Is the presence of enanthem a clue for COVID-19? (https://bit.ly/39F2bSV)  (JAMA Research Letter: https://bit.ly/3hNZnpK) *  *  * Things you will learn in this episode: * Extramammary Paget disease characteristically presents as an erythematous patch in sites with abundant apocrine glands, such as the vulvar, scrotal, or perianal skin. “Usually the typical story would be, this is a rash that has been treated as eczema for many years but it just doesn’t go away, and it is only until the dermatologist gets a biopsy that the diagnosis of [EMPD] is made,” Dr. Dany explains. * Classic biopsy findings include pagetoid spread through the epidermis with larger cells that have blue cytoplasm, dysmorphia, and nuclear atypia. It may appear similar to other pagetoid entities such as melanoma, intraepidermal sebaceous carcinoma, or squamous cell carcinoma in situ. * Primary and secondary EMPD present in clinically and prognostically different ways, but it is difficult to discern the 2 entities based on histology. * Extramammary Paget disease requires long-term follow-up to monitor for disease recurrence or further development of malignancies. “Every patient newly diagnosed with EMPD deserves a full workup for malignancy screening,” Dr. Dany explains. * There currently is no formal staging system or treatment guidelines for EMPD. “Wide local excision has been the default in the past, but recurrence rates were very high,” Dr. Dany notes. * More research is needed to understand the pathogenesis of EMPD, but data have shown that the PD-1/PD-L1 pathway may play an important role in future therapies. * Intralesional immunotherapies can be effective in treating EMPD in sensitive areas of the body. *  *  * Hosts: Nick Andrews; Daniel R. Mazori, MD (Brigham and Women’s Hospital, Boston) Guests: Mohammed Dany, MD, PhD (University of Pennsylvania, Philadelphia) Disclosures: Dr. Mazori reports no conflict of interest. Dr. Dany reports no conflict of interest. Show notes: Alicia Sonners, Melissa Sears *  *  * You can find more of our podcasts at http://www.mdedge.com/podcasts      Email the show: podcasts@mdedge.com Interact with us on Twitter: @MDedgeDerm