Supplementary Material for: Kaposi Sarcoma Associated with Pemphigus Vulgaris in the Setting of Immunosuppressive Therapy: Case Report and Review of literature

Introduction: Pemphigus vulgaris (PV) is a chronic autoimmune blistering disorder characterized by intraepidermal blisters affecting the skin and mucous membranes. The primary treatment for PV is systemic corticosteroid therapy, which is often prolonged due to the disease’s chronic and relapsing course. The interplay between autoimmunity and long-term immunosuppressive treatment can predispose patients to secondary complications, including Kaposi sarcoma (KS), an angioproliferative tumor primarily involving the skin and soft tissues. When KS develops in the context of immunosuppressive therapy, particularly in patients with autoimmune diseases such as PV, it is classified as iatrogenic KS. Case Presentation: We report the case of a 74-year-old female diagnosed with PV who developed iatrogenic KS following treatment with high-dose intravenous immunoglobulin (IVIG, 150 g) and systemic corticosteroids. Despite tapering of immunosuppressive medications, the KS lesions did not regress. As a result, the patient was referred to an oncologist for further evaluation and management. Conclusion: This case highlights the potential role of both autoimmunity and immunosuppressive therapy in the development of iatrogenic KS. While tapering immunosuppressive drugs has been reported as an effective approach for KS resolution in some cases, it may not be sufficient in all instances. Close monitoring and timely oncologic referral are essential in managing such complications.