Carcinoembryonic antigen in skin and related tumours as determined by immunohistological techniques.

Common benign skin abnormalities and related tumours were investigated for the presence of carcinoembryonic antigen (CEA) using immunohistological techniques in formalin-fixed tissue. CEA could be detected in all 10 squamous cell carcinomas examined, a finding which contrasted with those in earlier reports. CEA was not seen in normal skin but was present in the skins of 12-18-wk-old fetuses. Hence, CEA can be considered to be a true oncofetal antigen for ectodermal tissue. The antigen was not detected in seborrheic keratoses but was present in all 10 cases of keratoacanthoma. CEA was found in only one out of 10 basal cell carcinomas, the tumour being metatypical (basosquamous) in type. CEA was also observed in the minority of cases of solar keratosis and Bowen's disease. If the presence of CEA in proliferating epidermal tissue is associated with malignant transformation, both solar keratosis and Bowen's disease are indeed premalignant lesions whilst keratoacanthoma is the non-metastasizing variant of squamous cell carcinoma. Finally, the absence of CEA in basal cell carcinoma may help to explain its 'reluctance' to spread by metastasis.