[Malignant systemic mastocytosis (author's transl)].

The case of a 37 year old man with systemic malignant cutaneous mastocytosis is reported. The outcome was fatal after eight months. Death was due to a diffuse hemorrhagic syndrome which originated in an abnormal circulating heparinoid. Nosologically, this is a border-line case between mast cell leukemia and leukemic systemic mastocytosis.