Telangiectasia macularis eruptiva perstans (TMEP) lesion on a Hispanic female patients arm. TMEP is a rare form of cutaneous mastocytosis that is more common in adults. It results in flat macules on the skin with small dilated blood vessels near the surface (telangiectasias). Mastocytosis is caused by excessive numbers of mast cells in the skin that produce hives or lesions when irritated. Mast cells are granulocyte white blood cells and part of the bodys immune system. Treatment is with antihistamines.