Development of a gastric carcinoid tumor following allogeneic hematopoietic stem cell transplantation for early T-cell precursor acute lymphoblastic leukemia

Gastric carcinoid tumor is rarely diagnosed in children. We report a case of gastric carcinoid tumor that occurred after allogeneic HSCT. A 13-year-old girl with ETP acute lymphoblastic leukemia underwent allogeneic HSCT from a 7/8 HLA-matched unrelated donor. She presented with rashes, abdominal pain, and diarrhea, which were suggestive of GVHD, 7 months after HSCT. Immunosuppressive agents failed to resolve these symptoms well. After a series of evaluations, carcinoid syndrome caused by a gastric carcinoid tumor was diagnosed. The tumor was located in the antral region and resulted in partial gastric outlet obstruction. She received subtotal gastrectomy with regional lymph node dissection. However, she had a flare-up of GVHD 1 month after surgery, and immunosuppressive therapy was intensified accordingly. Although her GVHD was getting better, she developed respiratory syncytial viral pneumonia with rapid progression to respiratory failure. She died of multiple organ failure 2 months postoperatively. This is the first pediatric case of a gastric carcinoid tumor following allogeneic HSCT. Our case also highlights the necessity for pediatric transplant physicians to be aware of carcinoid syndrome caused by this rare tumor in the setting of GVHD with poor response to immunosuppressive agents.