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In the World Health Organization Classification of Brain Tumors Fifth Edition, mesenchymal non-meningothelial tumors involving the central nervous system are divided into three major categories: soft tissue tumors, chondro-osseous tumors, and notochordal tumors. Soft tissue tumors are classified into four groups: fibroblastic and myofibroblastic tumors, vascular tumors, skeletal muscle tumors, and tumors of uncertain differentiation. This article will focus on solitary fibrous tumors(SFTs), which are frequently encountered clinically and continue to undergo classification revisions in the 5 th edition, and outline the three newly added histological diagnoses. Although SFTs and hemangiopericytomas occur throughout the body, including the central nervous system, nomenclatures have been different between the classifications of "Tumours of Soft Tissue and Bone" and "Tumours of the Central Nervous System." The latest nomenclature is "SFT" in accordance with the nomenclature of bone and soft-tissue tumors. In addition, three new diagnoses, which are intracranial mesenchymal tumor FET-CREB fusion-positive, CIC -rearranged sarcoma, and primary intracranial sarcoma DICER1 -mutant, have been defined based on genetic abnormalities in tumors of uncertain differentiation.

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne viral hemorrhagic fever caused by the SFTS virus (SFTSV). Approximately 80 patients are infected annually, mainly in western Japan, and the case fatality rate is >20%. The clinical presentation of SFTS typically includes fever, thrombocytopenia, leukocytopenia, and gastrointestinal symptoms. Localized lymphadenopathy, coagulopathy associated with prolonged activated partial thromboplastin time, muscular symptoms, and neurological abnormalities referred to as SFTS encephalopathy are often observed. Besides tick-borne spread, SFTSV infection is increasingly being transmitted via SFTS-infected cats. Clinicians should remain mindful of this emerging viral infection.

Objectives　We investigated the infectious causes and management of Japanese spotted fever (JSF) and severe fever thrombocytopenia syndrome (SFTS), which are usually tick-borne infections, at a public health center in Ehime prefecture.Methods　The doctor diagnosing JSF and SFTS at the public health center reported the infectious cases using the questionnaire based on the Ehime Epidemiological Surveillance of Infectious Diseases Program.Results　There were 91 cases of JSF reported from August 2003, accounting for 56.5% of the whole Ehime prefecture. Since 67.0% of the JSF patients resided near the mountains with citrus cultivations, there were high chances of contact with ticks during farm work or their daily routine even if they did not visit the mountain areas. The distribution of the occupations of the JSF patients was as follows: citrus cultivator, 31.9%; farmer, 14.3%; and retired, 26.4%. The incidence of various clinical symptoms in the JSF patients was as follows: fever and systemic erythema, 100%; tick bite, 73.6%; liver dysfunction, 69.2%; disseminated intravascular coagulation (DIC), 14.3%; and neurological symptoms, 11.0%. The mortality rate was 1.1%. The incidence of DIC, which was considered a severe condition, was significantly low in patients with confirmed tick bites. There were 14 cases of SFTS reported from December 2013, accounting for 42.4% of the whole Ehime prefecture. Notably, 85.7% of the SFTS patients resided in the mountains. Moreover, 85.7% of the SFTS patients were retired. The incidence of various clinical symptoms in the SFTS patients was as follows: fever and marked leucopenia and thrombocytopenia, 100%; tick bite, 57.1%; diarrhea, 71.4%; neurological symptoms, 57.1%; and bleeding tendency, 42.9%. The mortality rate was 35.7%, and the average number of days from onset to death was 11.2 days.Conclusion　Since this region is one of the leading citrus producing areas in Ehime prefecture, JSF is considered an occupational disease. It is frequently caused by tick bites while working in the mountain areas of citrus cultivations. Hence, citrus growers should be cautious of tick-borne infections. Recently, the number of JSF cases has been gradually decreasing due to awareness and education of the inhabitants. Currently, SFTS is considered a category IV infection disease, but it can rapidly lead to death after the onset of hemophagocytic syndrome. Therefore, doctors should immediately transfer the patients diagnosed with SFTS to a hospital with an intensive care unit.

A sporadic but autochthonous dengue fever outbreak occurred in Tokyo in 2014, although the dengue virus is not in general circulation in Japan. Another lethal infectious disease, known as severe fever with thrombocytopenia syndrome (SFTS), was discovered to be endemic to Japan in January 2013. More than 400 patients with SFTS have been reported so far. The fatality rate of SFTS is approximately 30%. Also in 2014, a large outbreak of mosquito-borne Zika virus infections occurred in the South and Central parts of the American continent. Transplacental infection of a fetus with Zika virus occurs when pregnant women are infected. We cannot escape the risk of being infected with these viruses. Thus, preparedness for these emerging and reemerging virus infections is required.

Severe fever with thrombocytopenia syndrome (SFTS) was first reported in 2011 as an emerging virus infection caused by a novel Phlebovirus in the Bunyaviridae family [SFTS virus (SFTSV)]. In addition, it was reported to be endemic to Hubei, Henan, Shandong, and Heilongjiang provinces in China. The primary symptoms of SFTS are gastrointestinal symptoms such as fever, general fatigue, nausea, vomiting, and diarrhea. The total blood cell counts in patients with SFTS reveal thrombocytopenia and leukopenia. A woman in her 50s died due to multiorgan failure, intestinal hemorrhage, and hemophagocytosis in the autumn of 2012. She was retrospectively diagnosed with SFTS, suggesting that SFTS was endemic not only to China but also to Japan. Subsequently, SFTS was reported to be endemic to South Korea as well. Approximately 5 years have passed since the discovery of SFTS endemicity in Japan. To date, 40-100 patients with SFTS from the western part of Japan have been reported annually to the National Institute of Infectious Diseases. The case-fatality rate of SFTS is approximately 20%. This high case-fatality rate could be attributed to multiorgan failure, coagulopathy, and hemophagocytosis, which are induced in most patients with SFTS. Reportedly, an antiviral drug, favipiravir, was effective in treating SFTSV infection in an animal infection model. SFTSV has been found to circulate between wild animals and several species of ticks in nature, suggesting that we cannot escape the risk of infection with SFTSV and that SFTS will continue to occur in endemic areas. Hence, the development of specific treatment and preventive measures with SFTS vaccines is imperative.