[Successful intensive treatment for severe fever with thrombocytopenia syndrome complicated by virus-associated hemophagocytic syndrome in a very elderly patient].

The patient was an 89-year-old man who had been doing farm work for several days. He had previously visited a doctor with complaints of fever and nausea. He was referred to our hospital after pancytopenia was confirmed. On the 7th day after onset, he was found to have consciousness disturbances, liver dysfunction, and worsening pancytopenia, which led to a diagnosis of hemophagocytic syndrome by bone marrow examination. Considering the patient's history of outdoor activities and the presence of crusts on the right lower leg, we suspected severe fever with thrombocytopenia syndrome (SFTS). Reverse transcription polymerase chain reaction of peripheral blood was positive for the SFTS virus, confirming the diagnosis. Epstein-Barr virus reactivation was also observed. Steroid pulse therapy and plasma exchange led to prompt clinical improvement and hematopoietic recovery. The patient recovered without sequelae and was discharged home. Few reports have described the use of plasma exchange and steroid therapy in severe cases of SFTS. This case illustrates that early detection and aggressive treatment for elderly patients contributes to early symptom improvement and survival.