PMC5505921_01
Bone marrow aspirate showed hypocellular marrow (absolute nuclear cell count 1.1x109 cells/L) with increased proportions of macrophages, up to 13.6%. The macrophages engulfed red blood cells, thrombocytes, and nuclear cells. Original magnification, 1,000x.
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Bone marrow aspirate showed hypocellular marrow with increased numbers of monocytes and macrophages (13.4%), and hemophagocytosis was seen as shown in Fig. 1.
The tick that bit the patient on the back was identified as a semi-engorgedAmblyomma testudinarium nymph.
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On Day 4, a tick was found attached to the left side of the patient's back (Fig. 2), and it was removed while taking care not to leave the hypostome in her skin.
Clinical course in this case. The symptoms, WBC count, Hb level, platelet count, and the levels of AST, LDH, and CK are shown. The definite diagnosis of SFTS, accompanied by DIC and HLH, was made on Day 5, and she was treated with ribavirin, methylprednisolone (mPSL), and fresh frozen plasma (FFP). Her condition deteriorated rapidly, and she died on Day 6. APTT: activated partial thromboplastin time, CMZ: cefmetazole, CPFX: ciprofloxacin, GI: gastrointestinal, gamma-glb: gamma-globulin, MINO: minocycline, PZFX: pazufloxacin, RCC: red cell concentrate
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Upper gastrointestinal bleeding was also present, and she died shortly thereafter (Fig. 3).
Histopathological findings in the autopsy. (A) Bone marrow: Increased numbers of macrophages with active hemophagocytosis were seen in the bone marrow (Hematoxylin and Eosin (H&E) staining). (B) Liver: CD68-positive macrophages with hemophagocytosis were seen in the sinusoids and around focal necrosis. (a) H&E staining and (b) CD68 stain. (C) Spleen: CD68-positive macrophages with hemophagocytosis were seen in the red pulp. (a) H&E staining and (b) CD68 stain. Original magnification, 400x.
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In the bone marrow, we noted a massive invasion of CD68-positive macrophages, and hemophagocytosis was seen in the activated macrophages (Fig. 4A). The liver showed single-cell necrosis and focal necrosis in hepatic lobules, and the invasion of lymphocytes was seen in Glisson's sheath, with increases in the numbers of macrophages in the sinusoids and around focal necrosis (Fig. 4B). In the spleen, the accumulation of CD68-positive macrophages and hemophagocytosis was also seen in the splenic red pulp (Fig. 4C).
SFTSV was detected in the cytoplasm of the macrophages in the bone marrow (A), liver (B), and spleen (C). SFTSV protein was detected by immunohistochemistry (IHC) (left panel) and SFTSV RNA byin situ hybridization AT tailing (ISH-AT) (right panel). Original magnification, 400x.
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