Merkel cell carcinoma in Japan

Background. Merkel cell carcinoma (MCC) has increased in number. However, we do not know the real status of this tumor in Japan where aged persons have also increased in population. Cases of spontaneous regression have also accumulated. Methods. In 1995, questionnaires were sent to 460 Japanese dermatological institutions and to 1,124 ophthalmological institutions at both of which postgraduate training was being done. Results. Answers were obtained from 73% of dermatological institutions and from 61% of ophthalmological institutions. 174 cases of MCC were accumulated. Of them. 146 cases were from dermatological institutions. Grouped into decades, the 1970s were most in numbers. and the age group between 60 and 89 years occupied 83% of the cases. MCC was also seen mostly in the aged in Japan. 79.9% of the cases were seen on the head and the face; this figure was greatly larger than the group of Hitchcock ct al. who saw MCC in 48.9% in the same region. Spontaneous regression of MCC has increased to 13, of which 9 were reported in Japan.