Oral traumatic granuloma. Characterization of the cellular infiltrate.

Oral traumatic granulomas are reactive mucosal lesions that are characterized by an intense mononuclear infiltrate (usually with eosinophils) that may mimic neoplasia. These pseudoneoplastic infiltrates were evaluated with the use of lineage-associated antibodies (CD3, OPD4, L26, KP1, XIIIa, S-100, HPCA-1, HHF-35). We determined that the large distinguishing mononuclear cells were either CD68-positive macrophages or factor XIIIa-positive dendrocytes (the oral counterparts to dermal dendrocytes). S-100-positive connective tissue cells occasionally contributed to this infiltrate. Also abundant in the infiltrate were smaller CD3-positive T-lymphocytes. Double-staining confirmed that there were separate populations of CD68-positive macrophages and XIIIa-positive dendrocytes. Because some XIIIa dendrocytes coexpressed CD68, phagocytosis may be one of the functions of dendrocytes.