Distribution of lectin UEA-I in trichilemmal carcinoma, squamous cell carcinoma, and other epithelial tumors of the skin.

Trichilemmal carcinoma (TLC) is a cutaneous appendage tumor. In some cases, the histological distinction between TLC and squamous cell carcinoma (SCC) is difficult with hematoxylin & eosin staining. In the present study, in order to establish a simple and reliable method for distinguishing between TLC and SCC, we examined the lectin Ulex europaeus agglutinin-I (UEA-I)-binding patterns of TLC (4 cases), SCC (10 cases), malignant proliferating trichilemmal cyst (MPTC) (3 cases), Bowen's disease (4 cases), Bowen's carcinoma (4 cases), actinic keratosis (4 cases), basal cell carcinoma (8 cases), and eccrine porocarcinoma (1 case). In normal skin samples, UEA-I was strongly positive in the outer root sheath cells of the hair follicle and weakly positive in the granular layers of the epidermis. UEA-I stained the tumor cells of TLC clearly and some MPTC and Bowen's disease cells weakly. This result indicates that histochemical staining with UEA-I is a simple and useful method for distinguishing between TLC and SCC of the skin.