Supplementary Material for: Spontaneously regressing penile extramammary Paget disease without recurrence of primary urothelial carcinoma: a case report

Introduction: Secondary extramammary Paget disease (EMPD) is a rare cutaneous malignancy that typically manifests on apocrine-rich skin that originates from an underlying adenocarcinoma. It has a low chance of further metastasizing and treatment is recommended.
Case Presentation: We present a case of an 86-year-old man with a history of bladder carcinoma that was successfully treated and in remission for 4 years, who presents with an asymptomatic rash on the glans penis. Histopathology and immunohistochemistry confirmed secondary EMPD of urothelial origin. Cancer screening was negative and this was declared secondary EMPD without recurrence of primary malignancy. The patient declined surgical and pharmacologic treatment. After 1 year, the lesion spontaneously resolved with no recurrence.
Conclusion: Secondary EMPD can present without underlying malignancy and may spontaneously regress. This may be a rare phenomenon when there is no recurrence of underlying malignancy. Treatment decisions should be made in the context of thorough goals of care discussions. Further observation of this phenomenon is required to guide management plans.