Supplementary Material for: Recurrence of quadruple extramammary Paget's disease after 12 years: A case report and literature review

Introduction: Extramammary Paget’s disease (EMPD) is a rare skin cancer that tends to be multicentric, with quadruple EMPD cases being scarcely reported. Case Presentation: We report the case of an 81-year-old man with heterochronous quadruple EMPD. Twelve years after total resection of vulvar EMPD, the patient developed erythematous lesions on the resection margin in the lower abdomen, umbilical region, and both axillae. Histological examination revealed that all lesions were in situ EMPD. Considering the patient's wishes and the invasiveness of the surgery, the umbilicus and the lower abdomen were resected, and topical imiquimod was applied to the remaining lesions. All lesions were completely treated after nine cycles of imiquimod treatment. Discussion: We reviewed seven reported cases of quadruple EMPD with respect to race, sex, site, recurrence, time to recurrence, serum carcinoembryonic antigen, and depth. All patients were elderly Japanese males. In all but one case, the lesions were located in the apocrine region, which is a common site in such as the genital and axillary areas. Our case was the only heterochronous quadruple EMPD. The lesions were limited to the epidermis; therefore, they were unlikely to cause metastasis. It has been reported that the therapeutic effects of imiquimod can be expected in in situ EMPD. Therefore, quadruple EMPD may be a good indication of treatment option. Conclusion: EMPD is a disease whose pathogenesis is not yet clear; however, it is hoped that the origin and etiology of EMPD will be elucidated from the clinical features of multiple EMPD in the future.