Immunohistochemical demonstration of keratins 8 and 14 in benign tumours of the skin appendage.

The expression of keratins 8 and 14 was investigated immunohistochemically by the avidin-biotin-peroxidase (ABC) method using formalin-fixed paraffin-embedded specimens from 42 tumours of human skin appendages. Results were compared with the staining of 34 specimens from normal skin and skin appendages adjacent to the tumours. Keratin 14 was detected by the monoclonal antibody (mAb) 312C8-1, and was found in the basal cells of the epidermis, the outer root sheaths of hair follicles, and the peripheral cells of sebaceous glands. It was also detected in the inner and outer layers of cells in the ductal portion and the myoepithelial cells in the secretory portion of apocrine and eccrine sweat glands. Keratin 8 was detected by mAb 35BH11, and was present in the secretory cells of eccrine and apocrine sweat glands but not in myoepithelial or ductal cells. The pilosebaceous apparatus and the epidermis were uniformly negative. In benign skin appendage tumours, the staining patterns for both keratins generally resembled their distribution in the corresponding normal tissues. The demonstration of keratins 8 and 14 may be useful in the recognition, classification and diagnosis of skin appendage tumours.