Mast cell activation syndrome – MCAS – a stand-alone theory of everything. The disorder is not accepted by mainstream medicine. Hematologist deal with a set of serious disorders which may involve tumors but that’s is not what we are going to discuss--not to say mast cell activation syndrome is not a serious disorder. It can be deadly serious. MCAS is a novel way of looking at disease and is used to explain many diseases, symptoms and syndromes.
What is a mast cell? Mast cells are important actors within the immune system. Stained, under the microscope, they are plump purple cells. They are like other cells found in the blood (eosinophils, basophils) But these cells are located in tissues, various organs, outside the blood stream and around blood vessels. Mast cells have a role in allergies and killing certain parasitic worms. Not the topic of the day. We are interested in inappropriate action of the cells.
The granules inside the cells contain various substances which cause inflammation. These granules contain things like: enzymes, histamine, leukotrienes and prostaglandins.
Activation: These caustic immune cells release many inflammatory substances causing severe swelling, immune responses and local tissue injury. Instead of killing parasitic worms or attacking an allergen mast cells are attacking us and damaging our tissues. Mast cells are omnipresent and symptoms vary depending on which tissues are attacked. For example, if mast cells activate in the intestinal tract symptoms may include bloating, diarrhea, GERD and other dysfunction. Mast cell activation in muscles and joints causes joint pain and swelling. Mast cells activating in the brain may cause brain fog, headaches and neuropsychiatric symptoms. Diffuse mast cell activation can cause a “multisystem” presentation: fatigue, brain fog, joint pain, muscle pain, bowel and bladder dysfunction, neurological dysfunction, change in mood, confusion and many others.
Patients may experience one mysterious problem after the next. Symptoms may come and go over many years. Doctors scratch their heads or diagnose a psychosomatic disorder. Doctors will not think: MCAS. MCAS is a new paradigm on the edge of medical practice and medical science. Doctors don’t know about it – except for the few.
MCAS can explain a lot.
Mast cells don’t typically act on their own. They are triggered by something. Triggers vary widely from one person to the next.
Certain clinical scenarios make us think MCAS. Patients with hypermobility joint syndrome and POTS invariably also have MCAS. Lyme spirochetes may be a trigger as well as other infections.
We look for clues: Recurring hives, unexplained itching, dermatographia and facial flushing. Patients may report sensitivity to scents and smells and to variation in temperature – hot or cold. A patient I saw today is sensitive to certain fabrics. Chemicals may be a trigger. Foods and medicines are common triggers. It may be the inert ingredients in pills that triggers the response and some patients have all their meds compounded. All of the above may be absent.
Herxheimer reactions may have a MCAS component and may respond to appropriate therapy.
Are there lab tests? Iffy. Labs tend to positive only in severe forms of the disease, not the syndromes we are discussing. Occasionally serum tryptase or histamine may be elevated. 24-hour urine tests are sometimes abnormal. The diagnosis is usually clinical.
MCAS is treatable -- frequently with remarkable results and commonly used meds are extremely safe.
Diet may help. Certain foods are known to be high in histamine or trigger histamine release. Reducing intake of certain foods can help. Well-known examples include tomatoes, strawberries, avocado, nuts and deli meats. You may only have to cut down on certain foods, not eliminate them completely. Food reactions vary a lot amongst individuals.
MCAS is not an allergic reaction. For example, an allergy to peanuts is something different, mediated by different pathways in the immune system. Still – there is some overlap.
Meds. In most cases patients respond to simple, safe meds. But may have to take a lot of them. The treatment has 2 parts: Blocking the effects of inflammatory substances released from mast cells and stabilizing mast cells so they don’t activate in the first place. There are 2 kinds of histamine receptors called H1 and H2. H1 blockers are the familiar antihistamines. MCAS requires higher doses, and multiple antihistamines. The H2 blocker are thought of as ulcer/heartburn drugs, they block the production of stomach acid. The H2 receptors have other functions and blocking the receptors helps. Blocking leukotrienes (Singulair) is helpful. Prostaglandin blockers, anti-inflammatories like aspirin may help. Stabilization is more problematic. Cromolyn would be great but has poor bioavailabity but may still be effective. Ketotifen is mast cell stabilizer with antihistaminic properties. It is available through compounding pharmacies. Effective mast cell stabilizers may include benzodiazepines and cannabinoids. More difficult cases may be treated with the asthma/hives injectable Xolair and an array of immunosuppressive drugs.