A 62-year-old obese woman presented with a malignant melanoma (Stage la). In addition, she had disseminated telangiectatic macules on both thighs. Intensive rubbing of lesions resulted in wheals. Biopsy revealed increased numbers of mast cells. We diagnosed telangiectasia macularis eruptiva perstans, a rare clinical form of adult maculopapular cutaneous mastocytosis, a group which also includes urticaria pigmentosa. No evidence was found for systemic involvement. Possible associations with malignant tumors and the possible role of c-kit mutations both in development of melanoma and mastocytosis are discussed.