Mastocytosis is characterized by an accumulation of clonal mast cells in the skin and/or internal organs. Cutaneous mastocytosis is limited to proliferation and accumulation of mast cells in the skin, with no systemic disease. Systemic mastocytosis (SM) may also include skin lesions, which are referred to as mastocytosis in skin (MIS); however, a patient with SM would never also be given a diagnosis of CM. Systemic mastocytosis also involves at least one organ outside the skin, most often the bone marrow.

A recent study, Risk Factor Analysis of Anaphylactic Reactions in Patients with Systemic Mastocytosis (SM), by Theo Gülen et al., was conducted on 122 patients with SM at the Karolinska University Hospital in Sweden. To determine risk factors, patients were categorized into two groups, 55 who had anaphylaxis and 67 who did not.

The patients all underwent skin and/or specific IgE antibody diagnostic tests to categorize whether or not they were allergic (atopic) to food, pollens or other airborne factors, insects and drugs. General triggers, for example, stress, heat, cold and exertion, were reviewed and lab tests to measure the mast cell mediator, tryptase, were performed. Patients’ specific mast cell disease was evaluated with examination of the bone marrow, D816V KIT mutation, and CT scans of chest and abdomen. The presence of mastocytosis in the skin (MIS) was also evaluated. Patients who had only cutaneous mastocytosis, and therefore no mastocytosis in the bone marrow, were not included. Of the 122 patients with SM studied, 113 (92%) had indolent SM (ISM), 6 (5%) had SM with associated clonal hematological non-mast cell lineage disease (SM-AHNMD), now referred to as SM with an associated hematological neoplasm (SM-AHN), and 3 (3%) had aggressive SM.

Anaphylaxis was diagnosed according to the criteria of the National Institutes of Health. Triggers for anaphylaxis were wasp stings in 62%, idiopathic (unknown cause) in 31% and food and drug in 7%.

There were differences in the group with SM and anaphylaxis compared to the group with SM without anaphylaxis. Patients who had SM with anaphylaxis in comparison to those without anaphylaxis showed:

• less frequent presence of mastocytosis in the skin
• more atopic (allergy) predisposition
• higher total IgE levels
• lower baseline tryptase levels
• male sex, not statistically significant

The authors used their results to develop a scoring system to assess the risk level for anaphylaxis. Five factors were included: sex, absence/presence of MIS, atopic status, IgE level of more than 15 kU/L, and tryptase level of less than 40 ng/ml. This scoring tool had a sensitivity of 86 % (meaning it could identify 86 % of the patients with anaphylaxis from this study) and a specificity of 54 % (meaning it could identify 54 % of the patients without anaphylaxis from this study). The sensitivity was roughly the same when applying the scoring tool for venom (85 %) versus other (food, drug or idiopathic; 86 %) types of inducers of anaphylaxis.

In conclusion, the authors have developed a potential preliminary tool to separate patients with SM at high risk of anaphylaxis from those at low risk. They hope this tool may help improve the care of patients and may aid physicians to more accurately assess anaphylaxis risk, resulting in improved quality of life for patients. This study did have a number of possible weaknesses and limitations, leading the authors to recommend caution in the use of this anaphylaxis risk level assessment tool for patients with SM until it can be validated in larger, prospective, multicenter studies.

Addendum from The Mastocytosis Society, Inc.: We strongly urge all patients with all forms of mast cell disease to carry two doses of auto-injectable epinephrine at all times, and to be trained, along with their caregivers, on how to administer it.

This post is a short summary of the following recently published study:

Gulen T, Ljung C, Nilsson G, Akin C. Risk Factor Analysis of Anaphylactic Reactions in Patients With Systemic Mastocytosis. J Allergy Clin Immunol Pract. 2017 Mar 25.

A full text version may be available through THIS LINK (http://www.sciencedirect.com/science/article/pii/S221321981730096X). Information on the proposed scoring system used to assess anaphylaxis risk is shown in Table IV of the full text article.

Summary Article by

Hannelore Brucker, MD

June 2017

Edited by

Susan Jennings, PhD

Valerie M. Slee, RN, BSN

The Mastocytosis Society, Inc.

REFERENCES

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3. Gulen T, Ljung C, Nilsson G, Akin C. Risk Factor Analysis of Anaphylactic Reactions in Patients With Systemic Mastocytosis. J Allergy Clin Immunol Pract. 2017 Mar 25. http://www.ncbi.nlm.nih.gov/pubmed/28351784
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