1994 年 9 巻 2 号 p. 150-155
Although solar keratosis (SK) is commonly classified histologically into five types i.e., hypertrophic, atrophic, acantholytic, bowenoid and pigmented types, we added another type, spongiotic clefting type, which has spongiotic suprabasal cleft. Squamous cell carcinoma (SCC) derived from SK has been reported to have such histologic types as de novo, acantholytic and bowenoid SCCKs and small celled carcinoma. Of 109 cases of SK studied, hypertrophic type was 56.9%, atrophic type 5.5%, acantholytic type 4.6%, bowenoid type 17.4% and spongiotic clefting type 15.6%, respectively. Of 17 cases of SCC from SK, de novo type was 23.5%, acantholytic type 47.0%, bowenoid type 5.9%, and small celled carcinoma 23.5%, respectively. Acantholytic type of SCC having the highest rate of occurrence, possibly, derives from acantholytic type of SK. Thus, it is supposed that tumor cells of acantholytic type of SK have higher tumor invading rate. Using PCNA and AgNORs as index of cell proliferating rate, we examined all types of SK. However we could not have any significant difference among them.