Editorial comment to “Autopsy report of a sudden infant death that was strongly suspicious of Kawasaki disease”

Inflammatory cell infiltration/proliferation with aneurysmal dilatation is the principal feature of coronary artery in Kawasaki disease. However, its pathogenesis is still unclear. About cell infiltration/proliferation, Tanaka et al.1 described first in 1976 that “In several cases, the intima (of affected coronary artery) showed notable thickening due to proliferation of loose, fibrous granulation tissue accompanied by lymphocytic plasma cell and mononuclear cell infiltration; this infiltration, as well as destruction of muscle fibers, edema, and increase of collage fibers, was also evident in the tunica media.” They recognized it was an inflammatory cell infiltration as well as a proliferation of arterial tissue. After Tanaka's work, several notable investigations were performed stating that they were neutrophils, eosinophils, lymphocytes, atypical lymphocytes, plasma cells, monocytes, fibroblasts and fibrocytes,2-4 myoblastic cells, small mononuclear cells, large mononuclear cells accompanied by lymphocytes and plasma cells.5, 6 Recently Takahashi et al.7, 8 investigated these cells indicating there were many macrophages in the acute stage of Kawasaki disease. However, the mode of cell infiltration/proliferating is still ambiguous, because they seemed to be similar the cells appearing in some non-specific ordinary conditions so far studied and no distinctive type of cells especially characteristic in Kawasaki disease is specified. Then, it is much more important to specify the spectrum of cells contribute to Kawasaki disease in individual cases and in some group of cases. On the other hand, time-course of Kawasaki disease is interested, because acute inflammatory stage starts abruptly and progresses aggressively around the Day 12–25 day of disease (Stage II of Fujiwara and Hamashima3, 4 and in the descriptive tables in Masuda and Naoe5, 6). This case is 15 day of disease, which is in the middle of the so called acute inflammatory stage expected to be observed abundant inflammatory/proliferating cells. We can know much from this case in which several but sufficient immunohistochemical stains related to the proliferative, lymphocytic, monocytic, macrophage, and smooth muscle cell characters were performed. To investigate the spectrum of infiltrating/proliferating cells, this case report is important to go into a new step of the investigation, what kind of special assembly of infiltrating/proliferating cell population in Kawasaki disease. The author declares no conflict of interest.