When your immune system overstays its welcome: the mystery of mastocytosis
In short: Mast cells are vital defenders against infection, but in mastocytosis, they multiply uncontrollably and accumulate in your tissues. When triggered by stress or even a simple insect sting, these rogue cells flood your body with histamine, turning a routine immune response into a life-threatening medical emergency.
Mast cells are specialized immune cells produced in the bone marrow that typically act as sentinels, releasing histamine to fight off pathogens. In mastocytosis, this process goes awry. The condition is characterized by an abnormal accumulation of these cells in tissues such as the skin, bone marrow, and internal organs. While the exact cause remains elusive, most cases are linked to a random mutation in the KIT gene, which makes mast cells hypersensitive to stem cell factor, a protein that drives their survival and proliferation.
The disease manifests in two primary forms. Cutaneous mastocytosis, which predominantly affects children, is largely confined to the skin and often resolves by puberty. Systemic mastocytosis, more common in adults, involves the infiltration of organs. Within this category, indolent systemic mastocytosis is the most frequent, accounting for approximately 90% of adult cases. More severe variants, such as aggressive mastocytosis or those associated with blood disorders like leukaemia, can lead to organ damage and significantly impact life expectancy.
Diagnosis often begins with a physical examination, such as checking for Darier's sign—where stroking skin lesions causes redness and inflammation. For systemic forms, clinicians rely on blood tests to measure tryptase levels and bone marrow biopsies to identify dense clusters of abnormal mast cells. Because there is no cure, management focuses on symptom control. Patients often use antihistamines to block histamine effects and topical steroids for skin lesions. Crucially, those at risk of anaphylaxis—a severe, systemic allergic reaction caused by massive histamine release—must carry adrenaline auto-injectors to manage potential life-threatening episodes triggered by factors like physical exertion, alcohol, or emotional stress.
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Sources
- Summary by Intellect · source: Mastocytosis
- Also: Systemic mastocytosis - Symptoms and causes
- Also: Mastocytosis
- Also: my.clevelandclinic.org — Mastocytosis
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