Twenty year autopsy statistics of myocarditis incidence in Japan

In the annuals of autopsy records in Japan, edited by the Japanese Society of Pathology and covering 20 years, from 1958 to 1977, 377841 autopsy cases are registered with a short summary of the pathology findings. Of these, 434 cases with idiopathic, interstitial, viral, non-specific (NSM) and giant cell (GCM) myocarditis were found. The incidences of NSM and GCM were 0.11 and 0.007%, respectively. The annual incidence of NSM showed periodic fluctuations with in 5-year intervals and increased remarkably after 1974. Incidence of GCM showed a similar fluctuation but with a one to two year delay of peaks. The male to female ratio was 1.2: 1 and the age distribution had two peaked patterns for both sexes, though these peaks were scattered widely from neonate to elderly patients. The regional distribution of NSM showed a concentration in the middle portion of Honshu and its regional annual incidence had propagation waves from the central area to peripheral areas. The same tendency was observed in GCM cases. Hokkaido was characterized by a low incidence of NSM and no GCM. Complications of myocarditis included pancreatitis, pneumonitis, interstitial nephritis, meningoencephalitis, hepatitis, hepatic cirrhosis and a considerable incidence of malignancies. Antibiotics, antineoplastic agents, steroids and irradiation therapy were the main forms of treatment applied before or after the start of myocarditis.