IMMUNOHISTOCHEMICAL STUDY OF PRIMARY AND RECURRENT BASAL-CELL AND METATYPICAL CARCINOMAS OF THE SKIN

We investigated cell proliferation and expression of cytoskeletal prot eins in 32 cases of primary basal cell carcinomas (BCC), 10 cases of r ecurrent BCC, and 10 cases of metatypical carcinomas (MTC). Paraffin-e mbedded biopsies were evaluated immunohistochemically with a battery o f antibodies. Antibodies to proliferating cell nuclear antigen (PCNA) demonstrated comparatively low numbers of proliferating cells in 25 of 32 cases of primary BCC. In contrast, both recurrent BCC and MTC exhi bited three to four times higher levels of proliferating cells than pr imary BCC. PCNA-positive cells were usually distributed uniformly thro ughout the lobules; at times, however, they were localized to the oute r areas of those neoplasms, with a comparatively low level of prolifer ation index. Antibodies to keratin 17 strongly stained cells of all BC C cases, and antibodies to keratin 8 reacted with most of them. In con trast, the staining intensity of both types of keratin in MTC was decr eased six to eight times as compared with all BCC. In addition, cells of eight BCC and three MTC reacted with antibodies to smooth muscle a- actin and myosin, neoplasms that did not differ by the number of PCNA- positive nuclei from carcinomas with out contractile proteins. The dif ferences in cell proliferation and keratin expression between BCC and MTC may be useful criteria for further distinguishing these carcinomas . The appearance of contractile proteins in some BCC and MTC may be th e result of, or implies, myoepithelial differentiation.