Massive subchorionic thrombohematoma is uncommon but associated with a poor perinatal prognosis. Placental enlargement was detected in a 25-year-old Japanese primipara woman with fetal growth retardation and oligohydramnios at 23 weeks’ gestation. Ultrasonography (USG) showed an abnormal sonolucency within the placenta at 28 weeks’ gestation, but could not give an unequivocal differentiation from placental abnormalities such as hematomas, cysts and other tumors. Magnetic resonance imaging (MRI) pointed to a large hematoma in the subchorionic region. Simultaneously, the amniotic fluid was brownish colored. From these findings, it was possible to have prenatal diagnosis of massive subchorionic thrombohematoma. At 32 weeks’ gestation, the fetus died in utero and was stillborn 3 days later. Pathological findings for the placenta revealed a large hematoma diffused between the villous chorion and the chorionic plate, with wide necrosis of placental tissue, likely due to formation of multiple thrombi. The clinical and pathological findings were compatible with massive subchorionic thrombohematoma. MRI might be useful for the detection of massive subchorionic thrombohematoma and help its clinical management in combination with USG and pulse Doppler imaging.

SUMMARYWhen athymic nude (nu/nu) and heterozygous littermate (nu/+) mice were injected intraperitoneally (i.p.) with a mouse-adapted strain of dengue virus (DV), the following differences were noted in the course of infection. (i) The average survival time of nu/nu mice was longer than that of nu/+ mice, although the mortality ratios were not significantly different. (ii) DV persisted in some of the nu/nu mice for long periods of time without exhibiting any symptoms but they died after prolonged incubation periods. These aspects were not observed in the nu/+ mice. (iii) Infected nu/nu mice produced IgM antibody only transiently in the early stage of infection but they did not subsequently show regular IgG antibody production which normally occurred in nu/+ mice. (iv) Piamatral and perivascular mononuclear cell infiltration in the infected brain was more intense in nu/+ than in nu/nu mice. It is suggested from these data that the course of DV infection in mice is affected by the availability of thymus-derived lymphocytes (T-cells).Infectious virus was detected in various organs and tissues of infected mice. The hearts of nu/nu mice tended to show higher virus titres than those of nu/+ mice, whereas the virus concentrations in the brain, skeletal muscle and lymph node were the same in both groups of mice. Specific DV antigen was revealed by the fluorescent antibody (FA) technique in cells located in the infected tissues.

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A 2-year-old girl living in southwestern Japan had a nodule of 2 months' duration on the left foot. A biopsy from the lesion showed transverse sections of a worm surrounded by granulomatous tissue. The worm was identified as an Onchocerca sp. from the morphological characteristics such as relatively thick cuticles, annular ridges on the cortical layer, and high somatic muscles. Positive serological tests using ELISA for Onchocerca gutturosa and Onchocerca volvulus supported the diagnosis. This was the first case of zoonotic Onchocerca infection detected in Japan. The clinicopathological aspects of zoonotic onchocerciasis of this case were discussed.