Figure 1.

In adult patients without evidence of mastocytosis in the skin (MIS) but suspected systemic mastocytosis (SM), the basal serum tryptase level is an important initial screen parameter. In patients who have a clearly elevated basal tryptase, a bone marrow biopsy has to be considered. In patients with normal or slightly elevated tryptase, peripheral blood cells should be examined for the presence of KIT D816V using a highly sensitive test. In patients in whom typical signs and symptoms (osteoporosis, histamine-symptoms, anaphylaxis with negative allergy-test) or KIT D816V are detected, a bone marrow biopsy should be performed. If the KIT mutant is not detectable and symptoms are non-specific or can be explained by another disorder involving mast cells (e.g. allergy), the patient will be examined in the follow up, including repeated examinations of blood counts and serum tryptase levels.