WP 2.5 - Differential diagnosis: Mastocytosis


Patients with mastocytosis face an increased risk for anaphylaxis. The reported cumulated prevalence of anaphylaxis in patients with mastocytosis is 22-49% in adults and 6-9% in children. Reactions may be IgE- as well as non-IgE mediated. Mastocytosis should be suspected in cases with elevated basal s-tryptase and/or typical skin lesions  – however mastocytosis may be present with normal levels of s-tryptase and skin lesions may be inconspicuous. Further, elevated levels of s-tryptase indicating an increased mast cell load somewhere in the body are found in patients without visible skin lesions.

Finally, special attention should be directed to emergency treatment plans in the subgroup of mastocytosis patients at risk of anaphylaxis, requiring a thorough diagnostic work-up in all patients.




Mastocytosis is probably under-diagnosed and may be responsible for a substantial part of “idiopathic” anaphylactic reactions seen in Emergency Room, in the operating theater and in systemic reactions, triggered by insect stings in patients without IgE-sensitization.

Correct diagnosis and management will improve safety and thereby also Quality of Life for these patients.

Predictors or risk factors for anaphylaxis in mastocytosis may be identified at the clinical as well as molecular level.

The subgroup of patients at risk of anaphylaxis should be equipped with Adrenaline for auto-injection.

Risk of anaphylaxis in childhood mastocytosis is probably comparable to healthy children, but identifying possible predictors or risk factors is of importance in order to identify children at risk. 



Retrospective analysis of prevalence and triggers of anaphylaxis in the cohort of patients with mastocytosis and with elevated s-tryptase at our Mastocytosis Centre.

Detailed characterization of patients with anaphylaxis (triggers, facilitators such as drugs or exercise, mast cell load, concomitant diseases such as asthma) compared to patients without anaphylaxis including allergological, laboratory and hematopathological workup.

Prospective study and follow-up of patients with mastocytosis from WP1.1 and WP 1.2. These patients will undergo an identical evaluation program.

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