Isolated gastric Kaposi sarcoma following allogeneic 2 hematopoietic stem cell transplantation: A Case Report and Literature Review

Background Kaposi sarcoma (KS) is a rare complication after hematopoietic stem cell transplantation (HSCT). Case presentation We report a 20-year-old male with severe aplastic anemia who underwent HLA-matched sibling allogeneic HSCT. Three months later, he developed abdominal pain, nausea, and diarrhea suspected to represent gastrointestinal graft-versus-host disease. Endoscopic evaluation revealed multiple ulcerated gastric nodules, and histopathologic examination demonstrated spindle-cell proliferation with positive HHV-8 and CD34 immunostaining, confirming KS. Staging with computed tomography of the chest, abdomen, and pelvis showed no additional visceral involvement, and examination of the skin and mucous membranes showed no evidence of cutaneous or mucosal disease. Immunosuppression was gradually tapered. However, the patient developed rapidly progressive respiratory failure with positive blood HHV-8 polymerase chain reaction. HHV-8 pneumonitis was suspected but could not be confirmed, and the patient died despite supportive management. Results A literature review identified 20 reported cases of KS following HSCT. Most cases occurred within the first year after transplantation while on immunosuppression. Cutaneous involvement was the predominant presentation, whereas isolated visceral disease was exceptionally uncommon. Reduction or discontinuation of immunosuppression was the most frequent treatment option, while visceral involvement was associated with poorer outcomes. Conclusion To our knowledge, no previously published case of isolated gastric KS following allogeneic HSCT was identified in our literature search. It highlights the importance of considering KS in the differential diagnosis of gastrointestinal symptoms after HSCT and supports early endoscopic biopsy with HHV-8 immunohistochemical evaluation to facilitate timely diagnosis.