What is Mast Cell Disease?

Mast Cell Diseases are diseases that impact mast cells.

A mast cell is a type of cell found in the connective tissues in the body. They are located in the skin, lining of the gastrointestinal tract, bone marrow, airway, and other organs. Mast cells contain granules that store chemicals called mediators. These chemicals are released as part of the body’s normal response to injury or exposure to something the body deems as a threat, like an allergen. The chemicals released can cause a host of allergic and non-allergic presenting signs and symptoms. [x]

There are numerous types of Mast Cell Disease.

The most common is called Mastocytosis.

  • mast – in reference to a mast cell
  • cytosis – a condition in which there are more than the normal number of cells

Therefore, Mastocytosis is a condition in which there is an abnormal number of mast cells in the body. There are two types of Mastocytosis: [x]

1. Cutaneous Mastocytosis: where mast cells numbers are increased in the skin, but not elsewhere in the body. It causes abnormal lesions, spots, and bumps on the skin.

2. Systemic Mastocytosis: Primarily affecting adults, mast cells proliferate in the tissues, like the skin, organs, and bones.  There are various forms of Systemic Mastocytosis. The disease is classified as either indolent, which means it is slow-growing, or aggressive, which means it is fast-growing. As the number of mast cells builds up in an organ, the symptoms of the disease may get worse. Systemic Mastocytosis can become cancerous, resulting in Mast Cell Leukemia or Mast Cell Sarcoma. [x]

Also under the umbrella of Mast Cell Diseases is:

1. Mast Cell Activation Syndromes (MCAS, MMAS): presenting much like Systemic Mastocytosis symptom wise, it is defined as having a normal number of mast cells (or very mild proliferation) that have an activation problem.

The mast cells constantly “misbehave” and release their chemicals over anything and everything. MCAS is a condition with signs and symptoms involving the skin, GI tract, cardiovascular, respiratory, and neurologic systems. It can be classified into primary, secondary, and idiopathic. [x]

As an immune cell, mast cells release a variety of enzymes and chemical mediators when the body is injured or exposed to a trigger (like an allergen). Examples of the chemical mediators released by degranulating mast cells are prostaglandins, leukotrienes, and histamine—the latter being why antihistamines are vital drugs for Mast Cell Disease sufferers. However, mast cells also release an enzyme known as tryptase.

The high levels of histamine, tryptase, and the other 200+ chemical mediators in the body lead to the painful symptoms of the disease. An increase in mast cells and/or improper mast cell activation causes excessive mediator release because the mast cells are easily triggered. Common triggers are foods, medications, stress, heat or cold, airborne and applied chemicals from perfumes, lotions, detergents, hair products, soaps, etc. Once mast cells are triggered, they can continue to degranulate or release chemicals, over literally anything…even water. It is similar to an allergy, but the triggers constantly change and mast cell patients rarely test positive for true IgE allergies.

  • Life-threatening anaphylaxis
  • Organ swelling
  • Low or high blood pressure
  • Fainting
  • Flushing
  • GI Distress (nausea, vomiting, diarrhea, etc.)
  • Hives and Itching
  • Bone pain
  • And more

Mastocytosis is an orphan genetic disease. An orphan disease is one that is very rare. Genetic means that it involves hereditary transmission and/or some form of mutation. In most cases of Mast Cell Disease, especially in Mastocytosis, this mutation affects the KIT gene that normally encodes for a protein in the receptor tyrosine kinase family of proteins. KIT protein signaling is important for the development of certain cell types, including mast cells (which are a type of immune cell). [x]


Since mast cells live in connective tissues, Mast Cell Diseases, are commonly diagnosed along with connective tissues disorders, like Ehlers Danlos Syndrome. Mediator release from mast cells compromise the connective tissues, which is the “glue” that holds the body together and results in the joint laxity typically seen in Ehlers Danlos Syndrome Type 3 and Joint Hypermobility Syndromes. The complete understanding of the genetic and environmental link is still unknown.