Phlegmonous Gastritis During Consolidation Therapy With High-Dose Cytarabine and FLT3 Inhibitor in FLT3-ITD-Mutated Acute Myeloid Leukemia

Phlegmonous gastritis (PG) is a rare disorder in which a bacterial infection arises in the gastric wall. We report a patient in his 60s with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD)-mutated acute myeloid leukemia (AML) who developed PG during the consolidation therapy with high-dose cytarabine and the FLT3 inhibitor quizartinib. The patient developed fever, abdominal pain, hematemesis, and hypovolemic shock during neutropenia on day 17. Contrast-enhanced computed tomography (CT) showed edematous thickening of the gastric wall with perigastric fat stranding. Upper gastrointestinal endoscopy revealed diffuse edematous mucosa with erosions, and a gastric biopsy culture yielded Enterococcus faecium. Intravenous piperacillin/tazobactam, followed by ampicillin/sulbactam after clinical improvement, achieved complete clinical and radiologic resolution without surgical intervention. This case highlights the importance of early suspicion, prompt contrast-enhanced CT, and endoscopic biopsy with concurrent microbiological evaluation, followed by timely broad-spectrum antimicrobial therapy in immunocompromised patients with chemotherapy-induced neutropenia in the setting of hematological malignancy.