Résumé
Great difficulty may be encountered in the differentiation of basal cell carcinoma from trichoepithelioma snd, in some cases, it may even be irnpossible. Immunohistochemical methods using peanut agglutinin(PNA) which is glycoprotein of non-immune origin selectively binding to galactose-N-acetyl-galactosa-mine are increasingly used in dermatopathology to improve the diagnosis and differential diagnosis. Using PNA, anti-PNA antibody, and peroxidase antiperoxi-dase(PAP) technique, normal skin specimens, basal cell carcinomas, trichoepitheliiomas, and a variety of different skin tumors were studied, and different PNA Ibinding sites between basal cell carcinomas and trichoepitheliomas were observed. The results were as follows : l. In normal skin, except the basement membrane, epidermis and hair follicle epithelium showed a cell membrane staining of PNA, which stained weakly in the Ibssal cell layer. Sebaceous glands revealed membranous and cytoplasmic staining of PNA, but sweat ducts and duct coi1s were mostly negative. 2. 34 of 36(94.4%) basal cell carcinoma sections demonstrated peritumorous PNA-positive bands, and none of 5 trichoepithelioma sections showed peritumorous PNA-binding. 3. Peritumorous PNA-positive bands were strongly positive in solid and keratotic basal cell carcinomas, but decreased or absent in the vicinity of the ulceration or the dense inflammatory infiltration. 4. None of the other skin tumors(squamous cell carcinoms, keratoscanthoma, Bowens disesse and actinic keratosis} showed a periturnorous PNA-positive band. Therefore, we believe that the PNA staining on paraffin-embedded sections using PAP technique can be a useful probe for the differentiation of basal cell carcinoma from trichoepithelioma.