Verruciform xanthoma: Immunohistochemical characterization of xanthoma cell phenotypes

Background: Verruciform xanthoma (VX) is a benign lesion that primarily affects the oral cavity, most frequently the gingiva. VX lesions are characterized by xanthoma cells (lipid-laden macrophages or foam cells) found in the superficial connective tissue. To characterize these foam cells further, immunohistochemical techniques were used to investigate the presence of macrophage subpopulations in oral lesions of VX. Methods: Sixteen biopsy samples of VX lesions from the oral cavity (six from gingiva, three from palate, and seven from other mucosa) were studied. Immunohistochemical anaalysis was performed using antibody probes to macrophage subpopulations, including RM3/1 (reparative), 25F9 (resident), and 27E10 (inflammatory). The percentage of antibodylabeled foam cells was determined by visual counts of selected fields within lesional connective tissue. Results: The proportion of VX lesions that demonstrated positive xanthoma cell reactivity with antibodies RM3/1, 25F9, and 27E10 was 100%, 88%, and 50%, respectively. Foam cells that stained positively with RM3/1, 25F9, and 27E10 represented 61.5% 19.6%, 51.8% 29.4%, and 10.9% 14.7% of the counted cells, respectively. When results were analyzed based on anatomic location (gingiva, palate, and other mucosa), there was no difference in the percentage of positively stained cells by anatomic site for any of the three antibodies (P > 0.05). Similarly, there were no differences between masticatory (gingiva and palate) and other mucosa (P>0.05). Conclusions: VX lesions contain primarily reparative and resident foam cells, with limited numbers of inflammatory macrophages, consistent with a chronic reactive process. These findings were independent of the anatomic site.