Current Classification of MCAS

1. Primary (Clonal) MCAS

Also referred to as monoclonal mast cell activation syndrome (MMAS).

• Clonal (genetically altered) mast cells are present

• Often associated with mutations such as KIT D816V

• May show expression of markers like CD25 or CD2

• Does not fully meet criteria for systemic mastocytosis, but overlaps biologically

• Currently considered a chronic condition without a definitive cure

2. Secondary MCAS

Mast cell activation occurs as a consequence of another underlying condition.

Common triggers include:

• IgE-mediated allergies

• Autoimmune or chronic inflammatory conditions

• Chronic urticaria (including physical forms)

• Infections or medication reactions

• Neoplastic (cancer-related) processes

In these cases, treating the underlying condition often leads to significant improvement or stabilization of mast cell-related symptoms.

3. Idiopathic MCAS

• No underlying trigger can be identified

• No evidence of clonal mast cells

• Symptoms clearly suggest mast cell activation (e.g. unexplained anaphylaxis)

The exact cause remains unknown.

It is possible that future research will uncover currently undetectable mutations or entirely different mechanisms that explain these presentations.

MCAS

More coming soon! Whatch this space. For now, here are some useful links below.

Where to get professional help

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What you can do for yourself right now

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Laboratory Testing

Information to lab diagnostic options in Germany

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Share your experiences to support research for MCAS

What I find hardest about having MCAS and how I manage it best

Over time I learnt to understand my triggers and through experimentation and adaptation, I learnt to know how to help myself best.

Infections

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Medications

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Dietary realted

Histamine rich food, ....

Mechanical factors

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Toxins and chemicals

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Stress

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Confusion about the unpredictability, intensity and cause of my symptoms and feeling helpless how to help myself was hardest about having MCAS.

Follow me on threads to share your observations too so we can learn from each other.

The link between hEDS and MCAS

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Is MCAS the chicken or the egg?

What we know so far....

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Diagnostic information

Information to lab diagnostic options in Germany

What to get tested

Understanding the labs

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Different expert groups are discussing how best to define and diagnose this condition. Proposed approaches include:

• A rise in tryptase of at least 20% above baseline plus 2 ng/mL

• Measurement of other mediators such as prostaglandins

• Clinical response to treatment (e.g. mast cell stabilizers, H1 and H2 antihistamines)

• The presence of symptoms consistent with mast cell mediator release

Because there is no full consensus yet, the following overview reflects current understanding while acknowledging ongoing uncertainty.