Background: Activated mast cells enhance the uptake of mast cell-derived proteoglycan-low-density lipoprotein complexes by macrophages.
Objective: We sought to investigate mast cell contribution to the pathogenesis of xanthoma.
Methods: Twenty cases of xanthelasma palpebrarum and 6 cases of tuberous xanthoma lesions were analyzed using immunohistochemical staining.
Results: Xanthelasma lesions contained up to 5-fold more tryptase-stained mast cells than tuberous xanthoma lesions. Tuberous xanthoma lesions especially showed extensive staining of tryptase around mast cells and within some macrophages and foam cells. More than 99% of mast cells in xanthelasma lesions contained both tryptase and chymase. Approximately 60% of mast cells represented only tryptase in tuberous xanthoma lesions where the ratio of macrophages to tryptase-stained mast cells was extremely high (15:1) as compared with xanthelasma lesions (2:1).
Limitations: A change in mast cell phenotype has not been necessarily proven.
Conclusion: Mast cells are activated under the microenvironment in which macrophages predominate rather than mast cells, which thus reflects the clinical phenotypes of xanthoma lesions.