Oral submucosal dendrocytes: factor XIIIa+ and CD34+ dendritic cell populations in normal tissue and fibrovascular lesions.

Factor XIIIa+ and CD34+ dendritic cells, believed to be subsets of monocyte/macrophages, have been identified in dermis and in dermal tumors. The purpose of this study was to determine the presence and distribution of analogous cell types in oral submucosa and oral fibro-vascular lesions. Antibodies to XIIIa, CD34, S-100 protein, and macrophage antigen (MAC 387) were tested on formalin-fixed, paraffin-embedded tissue sections from normal mucosa, peripheral fibroma (PF), peripheral ossifying fibroma (POF), peripheral giant cell granuloma (PGCG), pyogenic granuloma (PG), lymphangioma (La), benign fibrous histiocytoma (BFH), idiopathic histiocytosis (IH), angiofibroma (Af) using an ABC immunoperoxidase technique. Numbers of positively stained cells were compared to unstained cells in the tumors. XIIIa positive submucosal dendrocytes (CD34-, S-100-, MAC 387-) were found in abundance in normal tissue in characteristic distributions: collagen-associated, vessel-associated, and lymphoid-associated. The percentage of XIIIa+ cells in the oral tumors was as follows: PF: 10-30%, POF: 5-10%, PGCG: 0-5%, PG: 5-20%, La: 0%, BFH: 5-25%, IH: 0%, and Af: 10-20%. CD34+ dendrocytes (XIIIa-, S-100-, MAC 387-) were few in number and were found in deeper submucosa, especially around skeletal muscle. Other than blood vascular endothelium, CD34+ cells were not generally seen in the oral tumors studied. It is concluded that two previously unrecognized dendrocyte populations reside in normal submucosa. XIIIa+ cells participate in the formation of some oral reactive and neoplastic lesions.