[The underestimated depth of tissue invasion of xanthelasma--a histological study].

Background: The depth of tissue invasion of xanthelasma is of major importance in selecting the most suitable surgical procedure. Intraoperative findings let one assume, that despite the common presumption, xanthelasma are not limited to the superior dermis but that they may penetrate the entire dermis and reach into the orbicularis muscle. In this study the depth of tissue invasion of xanthelasma was measured in histological specimens.

Materials And Methods: Between 1993 and 2006 100 xanthelasmata of 78 patients were surgically removed and analysed. Histological specimens were examined by light microscopy and the depth of tissue invasion by fat-containing macrophages was measured using the digital picture analysis system AnalySIS® of Soft Imaging System Inc. The distance from the epidermis/dermis junction to the deepest "xanthelasma" cell (fat-containing macrophage) was measured. In addition, we classified the cases into 3 categories: 1) invasion into the dermis, 2) invasion adjacent to and 3) invasion into the stratum musculare.

Results: The thickness of the xanthelasmata ranged between 502.9 µm und 4429.5 µm (m = 1443.6 µm, M = 1333.6 µm, SD 716.1). In 58 % of specimens lipid-containing macrophages infiltrated the dermis (m = 1275.9 µm, SD 571.0), in 15 % of specimens they touched the stratum musculare (m = 1426.2 µm, SD 534.8) and in 27 % of specimens they even infiltrated this layer (m = 1813.4 µm, SD 937.6).

Conclusions: This study confirms our hypothesis that a significant part, namely 42 % of the xanthelasmata, infiltrates the entire dermis and reaches the stratum musculare or even invades into this layer. These xanthelasmata should not be treated by superficial laser therapy but should be better excised surgically.