Papillomavirus antigen in the epidermoid cyst of the sole. Immunohistochemical and ultrastructural study.

An epidermoid cyst of the sole was studied immunohistochemically and ultrastructurally. Papillomavirus particles were present in the horny layer and in the upper layers of the epidermis of the cyst and within the acrosyringeal epithelium overlying the cyst. Thickened basal lamina-like structures similar to those found in the eccrine sweat duct tumors such as in cylindroma and eccrine spiroadenoma existed at the epidermal-dermal junction of the cyst wall. Carcinoembryonic antigen was immunohistochemically demonstrated in the center of the epidermoid cyst and the DAB reaction products took the shape of a circle resembling that of the sweat ducts in the horny layer.