Mast cell activation syndrome
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.
D89.40 – Mast cell activation, unspecified
16697871000119100 – Mast cell activation syndrome
- Benign cutaneous flushing – Caused by emotion, temperature, food, or beverages
- Alcohol – May cause flushing directly or via its metabolite acetaldehyde. More common among patients of Asian descent that may have aldehyde dehydrogenase-2 deficiency. Certain drugs combined with alcohol may cause flushing.
- Menopause – Can be provoked by warmth, hot drinks, alcohol, and mental stress.
- Cluster headache
- Carcinoid / neuroendocrine
- Medullary carcinoma of the thyroid
- Renal cell carcinoma
- Pancreatic cell tumor (VIPoma) – History usually includes watery diarrhea.
- Anaphylaxis – May also cause elevated serum tryptase levels acutely.
- Mastocytosis – An important consideration in the pediatric population.
- Serotonin syndrome
- Parkinson disease
- Multiple sclerosis
- Autonomic hyperreflexia
- Trigeminal neuralgia
- Horner syndrome
- Systemic mastocytosis
- Frey syndrome