Mast cells are the major effector cells in allergy. Mast cell activation can be caused by both IgE-mediated and non-gE-mediated triggers. Mast cell disorders occur when mast cells either are (1) overabundant in number or (2) overreactive in nature and release too many chemicals too frequently.

 

These cells live in the skin and the mucous linings of the eyes, nose, mouth, and also internal organs such as intestines, stomach, liver, spleen, and lungs. They release many mediators including histamine, tryptase and prostaglandin as well as inflammatory cytokines which trigger allergic symptoms such as itching, swelling, and redness. Common triggers include alcohol, exercise, heat and humidity, stress, certain medications and many environmental and food allergens.

There are 2 main types of mast cell disorders:

Primary mast cell disorders which are subdivided into cutaneous and systemic mastocytosis. These rare disorders are activated by chaotically multiplying mast cells in response to an irregular internal signal. Cutaneous mastocytosis conditions are further divided into 3 categories: maculopapular cutaneous mastocytosis (also called urticaria pigmentosa), solitary cutaneous mastocytoma, and diffuse cutaneous mastocytosis. Systemic mastocytosis is a form of mastocytosis in which mast cells accumulate in internal tissues and organs such as the liver, spleen, bone marrow, and intestines.

 

All of these disorders cause flushed skin, hives, angioedema, stomach and intestinal cramping, diarrhea, wheezing, exhaustion, fatigue, and low blood pressure. Food, strenuous exercise, environmental factors, emotional stress, or insect bites can bring on the symptoms.

Mast cell activation disorders. Talk about itching hives and allergies to food and medications! These relatively common disorders are triggered by external stimuli: allergens, medications, infections, insect venom, and physical factors. The number of mast cells remains the same, but they become activated too easily by invading substances and release the cascade of chemicals that initiate the allergic reaction. In rare cases, secondary mast cell activation disorders are linked to autoimmune disorders or malignancies.

 

In many cases, the activation mechanism and triggers remain unknown, in such situations the disorder is referred to as idiopathic mast cell activation syndrome. Symptoms in general are similar to the mastocytosis presentation.

Mast cell disorders can be hard to diagnose because their symptoms are similar to those of many other conditions. Serum tryptase level (checked during acute attacks and at normal baseline) and 24-hour urine prostaglandin and histamine levels are used to establish the diagnosis. In addition, tissue and bone marrow biopsy samples are carefully examined under microscope for the shape and size of mast cells, as abnormal cells are known to have a “spindle” shape to them. Checking for a mast cell related mutation is another diagnostic test.

Patients should see an allergist for proper diagnosis and therapy of their mast cell conditions.

There is no cure for mast cell disorders, although proper diagnosis and treatment can control the symptoms, allowing patients with these conditions to live healthy and fulfilling lives.