Aim of this study was to contribute to the characterization of the cells which are responsible for the dispersion and the storage of the pigment in tattoos and stasis dermatitis (SD). The pigment bearing cellular populations of the dermis at the site of pigmentation were characterized employing hematoxylin-eosin (HE) staining, histochemical (Giemsa, MassonFontana and Perl’s staining) and an immunohistochemical method with the use of CD34, CD117, CD163, CD11c and vimentin markers in five cases of tattoo and nine cases of SD. HE staining showed perivascular, superficial, and profoundly cellular pattern (throughout the thickness of the dermis and probably in the most superficial part of the subcutaneous tissue) in four of the five cases of tattooing and in eight of nine cases of SD. In all cases the tissue inflammatory cell infiltrate consisted mainly by lymphocytes, macrophages, and a small number of mast cells. Pigment granules were found in the papillary and superior reticular dermis (n = 3, n= 4), throughout the thickness of the dermis (n = 1, n=3) and in the superior degrees of subcutaneous tissue (n= 1, n= 1) in the cases of tattooing and SD respectively. The deposited pigment was found mainly intracellular both in cases of tattoo and stasis dermatitis. The pigment bearing cells, were of elongated morphology and in at least some of them clear cytoplasmic outgrowths were evident. With the histochemical Masson-Fontana staining, both extracellular and intracellular melanin granules in elongated cells were detected in two cases of SD, while a small number of extracellular pigment granules in additional three cases. Perl’s staining revealed the presence of abundant hemosidirin deposits in all cases of SD. With the Giemsa staining and immunohistochemistry with CD117 marker no ink storage could be indentified in mast cells neither in cases of tattoo nor of SD. In all cases of tattoo and SD, all cells with pigment uptake were positive for vimentin and negative for CD117 and CD34 marker expression. Double immunohistochemical staining (for the expression of CD163 and CD11c antigens) confirmed that the main cell population with pigment uptake was the tissue or M2 macrophage both in tattoo and stasis dermatitis cases. A secondary cell population seems to be some dendritic cells and a minority were probably fibroblasts. The analysis of the composition of the cell population as a whole but also among the cells with pigment storage, showed that the percentages of different cell subpopulations with CD11c+/CD163+, CD11c-/CD163+, CD11c+/CD163- and CD11c-/CD163-immunophenotypes did not differ significantly between samples of both settings (p> 0.05). It turned out that the expression of the CD163 index is associated with the greatest pigment storage capacity. Certain differences between tattoo and SD cases (the OR of the ‘double positive’ cells with pigment storage is significantly lower, whereas the OR of the CD163-/CD11c- ‘double negative’ cells is significantly higher in tattoo compared to SD) are the consequence of differing modes of pigment dispersion within the tissue in the two conditions: The exogenous transepidermaly deposited pigment in the tattoo could reach only a subfraction of storing cells located in a narrower, more superficial tissue zone as opposed to the endogenous SD pigment that was available for storage for all potentially storing cells throughout the whole dermis.
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