This is the first case-series study showing an effect of 3-day methylprednisolone pulse therapy on refractory MP in children. This therapy is apparently an efficacious and well-tolerated treatment for refractory MP.

To determine the incidence and etiology of childhood thrombocytosis, over 15,000 platelet counts in 7,539 patients performed at a single regional hospital were reviewed. When thrombocytosis was defined as ≧500 × 10⁹/l of platelet counts, the condition could be diagnosed in 6.0% (456 cases) of the patients. All patients were classified as having secondary thrombocytosis. The incidence of thrombocytosis dramatically changed throughout child development; it was 12.5% in neonates, peaked to 35.8% in 1-month-old infants and then returned to 12.9% in 6- to 11-month-old infants. Thereafter, it gradually decreased with age to only 0.6% in 11- to 15-year-old children. Frequent causes of thrombocytosis included infection (67.5%), Kawasaki disease (9.4%), prematurity (7.7%) and iron deficiency anemia (6.4%). Thrombocytosis was an incidental finding in a substantial population of early infants. Thrombocytosis as a reaction to several types of infection and Kawasaki disease was more common in children under 7 years old, while autoimmune disease and tissue damage were major causes in children aged 11–15 years. No child had thromboembolic complications. These findings indicate that childhood thrombocytosis is a benign condition and its incidence and etiology seem to depend on age.

SummaryTo serologically determine the association of microbial superantigens and the pathogenesis of Kawasaki disease (KD), we conducted a case-control study. Serum IgG and IgM antibodies against staphylococcal enterotoxin A (SEA), SEB, SEC, toxic shock syndrome toxin-1 (TSST-1), and streptococcal pyrogenic exotoxin A (SPEA) were measured by an enzyme-linked immunosorbent assay in 293 serum samples from 65 KD patients on clinical days 1-28 and 120 control samples. The administration of immunoglobulin products, which contain high concentrations of IgG antibodies against all the superantigens, directly elevated antitoxin IgG antibodies in KD patients. In contrast, antitoxin IgM antibodies were not detected in immunoglobulin products. Actually, we found a significant elevation of IgM antibodies against SEA in KD patients in the first (median titre: 0·020, P < < < < 0·01 versus control), second (0·024, P < < < < 0·001), third (0·030, P < < < < 0·001) and fourth (0·038, P < < < < 0·001) weeks, compared to the controls (0·015). Significant differences of IgM antibodies were also true for SEB, TSST-1, and SPEA throughout the first to fourth weeks, and for SEC throughout the second to fourth weeks. The prevalence of KD patients having high IgM titres (> > > > mean + + + + 2SD of control values) to the 5 superantigens was increased with the clinical weeks, and reached 29-43% of KD subjects at the fourth week. This is the first study that describes kinetics of IgM antibodies against superantigens and clarifies the serological significance throughout the clinical course of KD. Our results suggest that multiple superantigens involve in the pathogenesis of KD.

Human parvovirus B19 (B19 virus) infection is known to induce aplastic crisis in patients with hemolytic anemia. In healthy subjects, B19 infection may sometimes cause mild pancytopenia, but these changes are transient and recovery is spontaneous. We report the first case of aplastic anemia in a previously healthy boy without any underlying diseases, following asymptomatic infection with the B19 virus. Laboratory examination initially showed thrombocytopenia, mild leukopenia in the peripheral blood, and severe hypoplastic bone marrow. Since pancytopenia developed and worsened progressively, immunosuppressive therapy was given, resulting in a complete remission. Despite the lack of an infectious prodrome, serological and histological analysis revealed an underlying infection with the B19 virus. Thus, B19 virus infection must be considered one of the causes of aplastic anemia in patients without underlying hemolytic anemia and an apparent episode of the viral infection.

Summary. To verify pathophysiological mechanisms underlying thrombocytosis in low-birth-weight (LBW) preterm babies, we evaluated kinetic changes in platelet counts and thrombopoietic cytokines including thrombopoietin (TPO), interleukin 6 (IL-6) and IL-11 in 24 uncomplicated preterm infants. Platelet counts in cord blood (CB) (265^64 Â 10 9 /l) were similar to adult levels, increased by d 14 (473^140 Â 10 9 /l), and then remained fairly constant. Thrombocytosis (. 500 Â 10 9 /l) was observed in 9/24 (38%) subjects. Mean TPO level in CB was 5´11^1´51 fmol/ml, peaked at d 2 (7´64^3´28 fmol/ml), decreased at d 5 (3´93^1´67 fmol/ml), and thereafter kept fairly constant during the remaining neonatal period. Compared with term infants, mean TPO levels of preterm infants in CB and at d 2 were significantly higher (P , 0´01). There was an inverse correlation between platelet counts and TPO levels (r 0´45, P , 0´001, n 88). Preterm neonates with thrombocytosis had significantly higher TPO values in CB than those without thrombocytosis (P , 0´05). There was no significant relationship between platelet counts and IL-6. IL-11 was not detectable. These results suggest that an early elevation of serum TPO levels is related to the subsequent thrombocytosis in LBW preterm infants.