Abstract
In a survey of 732 cases of basal cell carcinoma without apparent genetic or environmental background seen at Hyogo Cancer Center, 52 (7.1%) had multiple lesions. Fifteen of these developed new carcinoma metachronously. Another 37 cases had multiple carcinomas synchronously at the time of presentation and 4 of these 37 (11%) developed subsequent new carcinomas metachronously. The sites of the carcinomas were classified into three regions (head and neck, trunk, extremities) and also right or left side. The patients with 2 basal cell carcinomas in the same region tended to have tumors ipsi-laterally. A statistical analysis using the binomial test revealed that the probability of ipsi-laterality was significant (p=0.0006594). In addition, some patients had tumors in close proximity. These facts suggest the possibility of post-zygotic somatic mutation.
