In the course of the study of keratin expression in the epidermis of nevus sebaceus, several cells in the epidermis of nevus sebaceus were positively stained with CAM 5.2 antibody, which is known to be specific for the lower molecular weight cytokeratin and used as a marker of Merkel cell.

This study was intended to verify that CAM 5.2 positive cells found in the epidermis of nevus sebaceus are Merkel cells and to understand the meaning of CAM 5.2 positive j cells in the epidermis of nevus sebaceus.

The immunohistochemical stainings with CAM 5.2 and antibody to epithelial membrane antigen (EMA) performed on specimens of normal skin, epidermal nevus, nevus sebaceus and some appendage tumors. In order to confirm the nature of CAM 5.2 positive cells, the distribution of those were compared to that of Merkel cells and double labeling with CAM 5.2 and neurofilament was performed.

CAM 5.2 positive cells were also found in trichilemmoma developed associated with nevus sebaceus and the epidermis of normal paimoplantar skin. CAM 5.2 positive cells were also stained with antibody to EMA on serial sections cut from the same tissue blocks. The association of CAM 5.2 positive cell and nerve fiber was also demonstrated.

CAM 5.2 positive cells are seemed to be Merkel cells and their presence in the covering epidermis of nevus sebaceus suggests to the epidermis of nevus sebaceus may not be nevoid proliferation of epidermal keratinocytes.