Iatrogenic Kaposi Sarcoma Revealed by Acral Nodules With Silent Pulmonary Involvement in Two Patients Treated for Autoimmune Blistering Diseases

Iatrogenic Kaposi sarcoma (KS) is an uncommon but serious complication of prolonged immunosuppressive therapy. While most reported cases occur in transplant recipients, it may also develop in patients receiving corticosteroids for autoimmune dermatologic diseases. Early recognition is crucial, as presentation may be subtle and visceral involvement can occur without symptoms. We report two patients treated with prolonged systemic corticosteroids for bullous autoimmune dermatoses who developed isolated acral nodules on the toes. Both lesions were painless and clinically suggestive of vascular or melanocytic tumors. Histopathology confirmed Kaposi sarcoma with human herpesvirus-8 (HHV-8) positivity. Staging chest CT revealed asymptomatic bilateral pulmonary involvement in each patient. Corticosteroids were tapered and discontinued, and temsirolimus 25 mg IV weekly was initiated with antihistamine and dexamethasone premedication. Both patients demonstrated clinical stability and radiological persistence without progression at three-month follow-up. These cases illustrate that acral nodules may be the first sign of steroid-associated Kaposi sarcoma in non-transplant patients. Pulmonary dissemination may be silent, underscoring the importance of imaging. Mammalian target of rapamycin (mTOR) inhibition represents a relevant therapeutic strategy following the reduction of immunosuppression. Clinicians should maintain a high index of suspicion for Kaposi sarcoma in immunosuppressed patients presenting with new acral lesions. Prompt biopsy, staging, steroid tapering, and consideration of mTOR inhibitors may support disease control.