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Mast cell activation syndrome
Other Resources UpToDate PubMed

Mast cell activation syndrome

Contributors: Siddhanth Hegde, Susan Burgin MD
Other Resources UpToDate PubMed

Synopsis

Mast cell activation syndrome (MCAS) is a group of rare disorders that presents with symptoms of excessive chronic mast cell activation. MCAS can be primary, secondary, or idiopathic. In primary MCAS, a clonal population of mast cells is present. Patients may fulfill the diagnostic criteria for systemic mastocytosis or, in cases of a low mast cell burden, they may not (monoclonal mast cell activation syndrome). Secondary MCAS is most commonly caused by immunoglobulin E (IgE)-mediated allergic disease but is sometimes caused by non-IgE-mediated causes such as drugs, venoms, or other inflammatory disorders.

The underlying pathophysiology of MCAS involves excessive systemic activation of mast cells, leading to degranulation and release of vasoactive mediators such as histamine and tryptase. These mediators cause an array of symptoms and signs including flushing, pruritus, urticaria and angioedema, nasal congestion and pruritus, bronchoconstriction and throat swelling, headache, and diarrhea. A severe complication of MCAS is systemic anaphylaxis. The disease is often episodic in nature, with symptoms waxing and waning over time. MCAS is most commonly found in White females. Symptoms often start in childhood and continue into adulthood if left untreated.

Codes

ICD10CM:
D89.40 – Mast cell activation, unspecified

SNOMEDCT:
16697871000119100 – Mast cell activation syndrome

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

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Best Tests

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Management Pearls

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Therapy

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Drug Reaction Data

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References

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Last Reviewed:01/31/2022
Last Updated:02/06/2022
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Mast cell activation syndrome
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A medical illustration showing key findings of Mast cell activation syndrome : Abdominal pain, Diarrhea, Flushing, Nasal congestion, Dyspnea, Urticaria, Wheezing, Abdominal bloating
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