Iatrogenic Kaposi Sarcoma in an HIV ‐Negative Patient With Immune Thrombocytopenic Purpura Treated With Rituximab and Corticosteroids: A Fatal Extracutaneous Presentation

BACKGROUND: Kaposi sarcoma (KS) is a Kaposi sarcoma, an Human herpesvirus 8 infection-associated endothelial neoplasm that typically arises in the setting of immune deficiency. Iatrogenic KS in HIV-negative patients treated for Immune thrombocytopenic purpura is rare, particularly in those receiving immunosuppressive therapies such as rituximab and corticosteroids. These cases may present without characteristic cutaneous lesions, making early diagnosis challenging. CASE PRESENTATION: We report a 43-year-old man with immune thrombocytopenic purpura in whom rituximab was re-initiated due to recurrent thrombocytopenia while receiving corticosteroids and eltrombopag. Following the third weekly dose, he developed progressive cough and dyspnea over one month, accompanied by severe hypoxemia. Clinical evaluation revealed a buccal mucosal lesion and generalized lymphadenopathy. Computed tomography demonstrated extensive nodal involvement with bilateral pleural effusions, ground-glass opacities, patchy consolidation, interstitial thickening, and pulmonary nodules. Biopsies obtained from the buccal lesion and an axillary lymph node confirmed Kaposi sarcoma with positive immunohistochemical staining for Human herpesvirus 8 infection; HIV serology was negative. Treatment with weekly paclitaxel led to initial clinical improvement. However, the patient subsequently deteriorated due to pulmonary hemorrhage secondary to underlying ITP and died shortly after admission to the intensive care unit. CONCLUSION: This case highlights that Kaposi sarcoma should be considered in immunosuppressed but HIV-negative patients presenting with unexplained respiratory or mucosal symptoms and lymphadenopathy, even in the absence of skin lesions. Early histological confirmation is essential to avoid diagnostic delay and to guide appropriate management.