Factor XIIIa-containing cells and fibrosis in oral and maxillofacial lesions: an immunohistochemical study.

The distribution of subunit A of blood coagulation factor XIII (FXIIIa) was investigated by the avidin-biotin-peroxidase complex (ABC) method in various oral and maxillofacial tissues. These tissues were from normal tongue, gingiva, lip, and submandibular gland, and from Dilantin gingival hyperplasia (one case), pyogenic granuloma (three cases), peripheral fibroma (four cases), squamous cell carcinoma (seven cases), chronic sclerosing submandibular adenitis (two cases), and fibrous dysplasia of the mandibular bone (one case). The distribution of collagenous components was examined in the same tissues by means of the Sirius red F3BA method. By means of the ABC method, FXIIIa was detected in the cytoplasm of certain connective tissue cells in each of the tissues examined. These FXIIIa-containing cells were sparse in the normal tissues but evidently abundant in the fibrous connective tissue of inflammatory and neoplastic lesions. In the present study, the close relationship between the distribution of FXIIIa-containing cells and that of collagenous components is demonstrated. The role that FXIIIa-containing cells play in the process of fibrosis is discussed.