Hyperferritinemia Associated with Macrophagic Activation Syndrome (MAS) Complicating Salmonella Gastroenteritis: A Case Report

Macrophage activation syndrome (MAS) is a rare but potentially life-threatening hyperinflammatory condition that can complicate autoimmune diseases, malignancies, and infections. It is considered part of the spectrum of secondary hemophagocytic lymphohistiocytosis (HLH) and may affect both children and adults. Although MAS triggered by bacterial infections is uncommon, prompt recognition is crucial to ensure appropriate management. We report the case of a 7-year-old child admitted to the pediatric emergency department with severe Salmonellagastroenteritis complicated by MAS. The patient presented with persistent fever, diarrhea, vomiting, and signs of systemic inflammation. Laboratory investigations revealed pancytopenia, marked hyperferritinemia, and elevated liver enzymes, raising strong suspicion for MAS. Inflammatory markers, including C-reactive protein and procalcitonin, were significantly elevated, and Salmonella was isolated through stool culture. Bone marrow examination did not reveal hemophagocytosis; however, its absence did not exclude the diagnosis due to known variability in this finding. Based on the clinical presentation and laboratory findings, a diagnosis of MAS secondary to bacterial infection was established. The patient responded favorably to intravenous antibiotic therapy and supportive care, with rapid clinical and biological improvement. This case highlights the importance of considering MAS in children presenting with sepsis-like symptoms and cytopenias, even when bone marrow findings are inconclusive, particularly in the setting of confirmed bacterial infection.