Kaposi's sarcoma resolves after sirolimus therapy in a patient with pemphigus vulgaris

Background: Iatrogenic Kaposi's sarcoma (KS) has been reported in patients who use immunosuppressive regimens for the treatment of autoimmune disorders, malignant neoplasms, and organ transplant rejection. However, iatrogenic KS in the setting of pemphigus vulgaris (PV) has been infrequently observed. The conventional treatment strategy for iatrogenic KS has focused on reducing immunosuppression, which carries a poor prognosis owing to a substantial risk for exacerbation of the primary disease. Observations: A 49-year-old man developed KS on his wrist after 2 years of long-term immunosuppressive therapy with prednisone, methotrexate, and dapsone for well-controlled PV. Three months after the substitution of methotrexate with sirolimus, the KS gradually resolved. With the patient on a maintenance regimen of sirolimus, in conjunction with low-dose prednisone and dapsone therapy, KS and PV have remained in remission, without further recurrence, during a 24-month follow-up period. Conclusion: The present case introduces a novel therapy for this patient population, highlighting the efficacy of sirolimus in treating iatrogenic KS without sacrificing the immunosuppression necessary to maintain control of PV.