Fifty-three recurrences among 2,288 basal cell epitheliomas and squamous cell carcinomas in 49 patients treated by surgery, radiation, or curettage and electrodesiccation were evaluated clinically and pathologically. Clinical factors in recurrences include errors in diagnosis, improper technique, and inexperience. Pathologically aggressive behavior often was manifest as poor differentiation, invasiveness and large size, and, in basal cell epitheliomas, by a sclerosing tendency. Such factors could account for two thirds of the recurrences studied.
Freeman RG, Duncan WC. Recurrent Skin Cancer. Arch Dermatol. 1973;107(3):395-399. doi:10.1001/archderm.1973.01620180049015