Disseminated Kaposi Sarcoma Complicating Untreated Fanconi Anemia–Associated Very Severe Aplastic Anemia: A case report

Fanconi anemia (FA) is an inherited bone marrow failure syndrome characterized by chromosomal instability and high cancer susceptibility. Kaposi sarcoma (KS), an HHV-8–driven vascular tumor, is exceptionally rare in non-HIV, non-transplant patients with untreated severe aplastic anemia (SAA). The coexistence of both conditions creates a major therapeutic dilemma. Case presentation: A 25-year-old male was admitted for febrile neutropenia and severe hemorrhagic manifestations. Laboratory evaluation and bone marrow biopsy revealed very severe aplastic anemia (ANC <200/µL, platelets 16,000/µL, hemoglobin 3.7 g/dL). Viral serologies were negative. Bone marrow examination confirmed marked hypocellularity without clonal abnormalities or PNH clone. Chromosomal breakage testing established the diagnosis of Fanconi anemia, despite absence of phenotypic abnormalities. HLA typing identified a matched sibling donor. During hospitalization, the patient developed multiple violaceous cutaneous nodules. Skin biopsy demonstrated Kaposi sarcoma with CD34 and HHV-8 immunohistochemical positivity. HHV-8 serology was negative. Thoracic imaging revealed multiple bilateral pulmonary nodules consistent with disseminated KS. Immunosuppressive therapy was contraindicated due to FA. Hematopoietic stem cell transplantation, the only curative option for FA-related SAA, was precluded by active disseminated KS. Systemic chemotherapy for KS was not feasible because of profound marrow aplasia.Management was limited to supportive transfusion therapy. The clinical course was complicated by massive gastrointestinal bleeding leading to fatal hemorrhagic shock. Conclusion: To our knowledge, this is the first reported case of disseminated Kaposi sarcoma occurring in untreated FA-associated very severe aplastic anemia. This case highlights an unprecedented therapeutic impasse in which inherited marrow failure, oncogenic viral proliferation, and profound cytopenias mutually exclude standard treatment options. It underscores the vulnerability of FA patients to aggressive malignancies even before therapeutic immunosuppression and illustrates the critical need for adapted management strategies in this rare but catastrophic association.