Our study is the first investigation showing increased expression of HIF-1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mathrm{a}$$\end{document}a in lesional skin of HS patients. The gene discussed is HIF1A; the disease is histiocytic sarcoma.