Extramedullary gastric relapse of acute lymphoblastic leukemia following allogeneic stem cell transplant: staging with F-18 FDG PET/CT.

A 26-year-old man with a prior history of acute leukemia that was treated with a stem cell transplant (SCT) was referred for an F-18 FDG PET/CT to assess suspicious new gastric mucosal lesions. The lesions were FDG-avid and were histologically proven to be acute lymphoblastic leukemia (ALL). Extramedullary relapse of ALL after SCT is very rare, with only 60 cases reported in the literature, and the role of F-18 FDG PET/CT in monitoring for ALL relapse following SCT has not been previously investigated. This rare case report highlights the use of F-18 FDG PET/CT in staging gastric relapse of ALL following SCT.