tissues for allergic reaction

Is Mast Cell Activation Syndrome (MCAS) The Same As Mastocytosis?

Those who have severe allergies know all too well just how scary it can be to experience the symptoms of anaphylaxis. People at risk of this are constantly aware of their surroundings because just one thing can set off an attack. Although there are treatment options available for those who have both mild and severe allergies, it can still put a strain on daily living.

In some cases, anaphylaxis can happen to a person without them having an allergy at all. This type of condition is driven by the overaction of mast cells within the body. Mast cells are immune cells that release a substance called a mediator, which induces inflammation to help the body heal from an injury or infection. This condition is known as mast cell activation syndrome (MCAS). But what is MCAS, exactly? And is MCAS the same as mastocytosis?

What is MCAS?

Mast cell activation syndrome, or MCAS, is caused when the mast cells in the body release mediators frequently and at the wrong times. When there is no threat to the body and the mast cells release these substances, it can lead to symptoms of an allergic reaction.

These symptoms affect different parts of the body and can include:

  • The skin becoming itchy or flushed, breaking out in hives, or sweating profusely.
  • The eyes watering and becoming itchy.
  • The nose itching and running, often accompanied by frequent sneezing.
  • The mouth and throat becoming itchy or swollen to the point of blocking the airways.
  • Wheezing and trouble breathing.
  • Rapid heart rate and low blood pressure.
  • Gastrointestinal issues such as cramping, nausea, diarrhea, and abdominal pain.
  • Headaches, dizziness, confusion, and extreme tiredness.
  • Anaphylactic shock (in the most severe cases).
woman with allergies blowing nose
Image by Mojpe on Pixabay: MCAS and mastocytosis are both affected by mast cell defects and can cause symptoms similar to that of an allergic reaction, but that is where their similarities end.

Although the cause of MCAS is largely unknown, one study found that a genetic component may be at play, because 74% of people with the condition had a relative who suffered from it as well. While there is no cure for MCAS, the condition can be managed by using H1 or H2 antihistamines designed to block the effects of mediators released by mast cells, and mast cell stabilizers that prevent mast cells from releasing mediators.

Other treatments include:

  • Antileukotrienes that block a mediator substance known as leukotrienes.
  • Corticosteroids designed to treat edema or wheezing.
  • An epinephrine shot in the most severe cases.

What is mastocytosis?

Mastocytosis is another condition that can lead to an allergic-like reaction and is correlated with mast cells; however, it is not the same as MCAS. This type of mast cell condition is characterized as the build-up of mast cells under the skin or within bones, intestines, or other organs.

It can lead to symptoms such as:

  • Itchy bumps on the skin that could be accompanied by brown or red blotches and skin blisters.
  • Gastrointestinal distress such as diarrhea, nausea, vomiting, and stomach pain.
  • Bone pain.
  • Flushing of the skin all over the body.
  • Fainting and a drop in blood pressure.
  • Anaphylaxis.

In the most severe cases, mastocytosis can lead to death if it is left untreated for too long and becomes overly aggressive.

There are two types of mastocystosis:

  • Cutaneous. This type affects only the skin and occurs in children more than any other age group. It is also less likely to be life-threatening unless a severe allergic response is triggered.
  • Systemic. This type mostly occurs in adults and affects the bones, intestines, and organs. There are two types of systemic mastocytosis: mast cell leukemia, which is more aggressive and is characterized by a large number of mast cells in the blood and bone marrow, and mast cell sarcoma, which is when a tumor of mast cells forms in the body.

Mastocytosis is typically caused by a genetic mutation called KIT, although it is not inherited. There is no cure for mastocytosis, so it can only be managed with various treatments. They include:

  • Medications designed to reduce the symptoms of inflammation and allergy-like symptoms.
  • Epinephrine for those with severe allergic reactions.
  • Ultraviolet light to help darken skin and minimize the appearance of dark spots.
  • Chemotherapy or bone marrow transplant for aggressive cases.

What triggers mastocytosis?

Certain triggers can cause an attack in people with mastocytosis. It can be hard to determine what specific trigger will happen to each individual, because what causes an attack for one may not for another.

Some common triggers include:

  • Friction or rubbing on the skin.
  • Physical activity.
  • Wasp/bee stings and insect bites, with ant bites being the worst.
  • Medications including NSAIDs, muscle relaxers, and anesthesia.
  • Alcohol consumption.
  • Sudden temperature changes.
  • Emotional and physical stress.
immune system
Image by Swiftsciencewriting on Pixabay: Is mastocytosis an autoimmune disease? No, but it can cause chronic symptoms.

The difference between MCAS and mastocytosis

Although both MCAS and mastocytosis are caused by defects in mast cells, the two conditions are not one and the same. MCAS is driven by the mediators released by mast cells, whereas mastocytosis is driven by the overabundance of mast cells themselves.

The conditions also present with different symptoms, although both can lead to severe allergic reaction. Mastocytosis can be much more severe than MCAS, and the causes are also different, although the cause of MCAS isn’t clear. MCAS is considered to be one of the most common diseases affecting mast cells, while mastocytosis is quite rare.

Can MCAS turn into mastocytosis?

Since the mechanism behind MCAS is quite different than that of mastocytosis, the former is not likely to cause the latter. The only link between the two is that they are both caused by defects in the mast cells and how they operate within the body.

Featured image by Diana Polekhina on Unsplash

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