A case of novel swine influenza A (H1N1) pneumonia complicated with virus-associated hemophagocytic syndrome

Influenza related to complications such as pneumonia and encephalitis have sporadically been reported. However, influenza A (H1N1)-virus-associated hemophagocytic syndrome (VAHS) has rarely been reported. A 39-year old woman complained of high fever and was referred to us. Chest infiltrations in both lungs and a positive polymerase chain reaction (PCR) for novel swine-origin influenza A (H1N1) in bronchial alveolar lavage fluid (BALF) specimen was confirmed and she was diagnosed with influenza A (H1N1) pneumonia. Pancytopenia was found, and hemophagocytic syndrome (HPS) was diagnosed by bone marrow aspiration. Following intravenous administration of antiflu drug and combination therapy of steroid pulse and erythromycin IV, the patient’s respiratory dysfunction and lab data gradually improved and she was discharged on day 21. Whereas secondary HPS related to viral infections such as Epstein–Barr virus, cytomegalovirus, and human herpesvirus type 6 are commonly seen, H1N1 pneumonia complicated with secondary VAHS is rare.