Macrophage activation syndrome is a rare and potentially life-threatening disease. It occurs due to immune dysregulation manifested as excessive macrophage proliferation, typically causing hepatosplenomegaly, pancytopenia and hepatic dysfunction. Here, we report an unusual case of macrophage activation syndrome presenting as dyspnea, as well as (reported here for the first time) high resolution computed tomography findings of an excavated nodule, diffuse ground glass opacities and consolidations (mimicking severe pneumonia or alveolar hemorrhage). The patient was successfully treated with human immunoglobulin. We recommend that macrophage activation syndrome be considered in the differential diagnosis of respiratory failure. Rapid diagnosis and treatment are essential to achieving favorable outcomes in patients with this syndrome.

Keywords: Macrophage activation; Lymphohistiocytosis, hemophagocytic; Tomography, X-ray computed; Lung diseases, interstitial.