Hemophagocytic Syndrome Associated with Mycoplasma pneumoniae Pneumonia

Mycoplasma pneumoniae (Mp) sometimes causes immunological complications in children. We present a rare case of hemophagocytic syndrome (HPS) caused by Mp in a previously healthy 7-year-old Japanese girl. A chest radiograph obtained to evaluate the source of her fever showed infiltration in the lower right lung with mild splenomegaly. We could diagnose the patient with HPS on the basis of the hemophagocytic-lymphohistiocytosis- (HLH) 2004 criteria. She met the criteria for fever, splenomegaly, neutrophil count (<1,000/μL), platelet count (<10.0？×？104/μL), fasting triglyceride level (>265？mg/dL), and ferritin level (>500？ng/mL). Furthermore, a peripheral blood smear showed an increased number of monocytes/macrophages with erythrophagocytosis. Treatment with clarithromycin and prednisolone, which was initiated soon after the diagnosis, was successful. Mp infection might partly progress to HPS in certain conditions. Clinicians should be aware of HPS caused by Mp and start appropriate treatment as soon as possible if the disease is suspected. 1. Introduction Mycoplasma pneumoniae (Mp) is well known to cause upper and lower respiratory tracts infections, including pharyngitis, bronchitis, and pneumonia. Mp also causes immunological complications in children, such as Stevens-Johnson syndrome, Guillain-Barré syndrome, Kawasaki disease [1], aseptic meningitis, and hemophagocytic syndrome (HPS). HPS is characterized by abnormal activation of monocytes/macrophages and consequently overproduction of proinflammatory cytokines [2, 3]. Among various types of HPS, secondary HPS is often associated with infections such as virus, bacteria, fungi, and parasites [4]. However, Mp rarely causes secondary HPS, and there have so far been few reports concerning HPS due to Mp [5, 6]. We herein report a 7-year-old girl who was diagnosed as having HPS associated with Mp pneumonia, and we successfully treated her with an appropriate antibiotic along with corticosteroid soon after the diagnosis. 2. Case Presentation A previously healthy 7-year-old Japanese girl presented to her physician with three-day history of fever, cough, and malaise and was referred to our outpatient clinic by the physician for evaluation of fever and leukocytopenia. Physical examinations revealed mild hepatosplenomegaly, however, no lymphadenopathy nor skin rash. Chest auscultation revealed also normal breath sounds. A chest radiograph obtained to evaluate the source of her fever showed infiltration in the lower right lung with mild splenomegaly (Figure 1). Laboratory findings were as follows: white blood