Mast Cell Disorders (Mastocytosis)

Have you experienced unexplained flushing, abdominal pain and bloating, or reactions to foods, medicines, insect stings … or just feeling intolerably hot in a normal-temperature room? Do you wonder if your immune system has gone haywire?

It could be a mast cell disorder.

People with mast cell disorders can struggle with severe symptoms and life-threatening reactions for years before finding a doctor with answers. Some symptoms mimic allergy symptoms and a patient experiencing both allergies and a mast cell disorder may find one problem exacerbates the other.

Mast cell disorders are rare, but increasingly recognized by physicians. They are caused by mast cells that are abnormal and/or overly active. Infants may be born with a mast cell disorder or development can occur during childhood or adulthood. Mastocytosis and Mast Cell Activation Syndromes (MCAS) are the two main types.

What are mast cell disorders?

Mast cells protect us from foreign invaders like germs and parasites. Everyone has mast cells and although they are helpful, they are also important culprits in allergic reactions and anaphylaxis.

Mastocytosis patients have abnormal mast cells that can accumulate in various organs. The condition can be confined to the skin (e.g., urticaria pigmentosa, or UP) or present in various organs such as the intestine, liver, spleen, lymph nodes or bone marrow. The majority of mastocytosis forms are benign.

MCAS occurs in patients with overly reactive mast cells usually present at normal numbers.

In patients with mast cell disorders, mast cells can be triggered to release mediators, including histamine, tryptase, prostaglandins and leukotrienes, causing a host of symptoms.

Symptom triggers for patients with mast cell disorders can include heat, cold, temperature change, friction, stress, exercise, insect and other bites/stings, environmental odors or perfumes, alcohol, contrast dyes and certain foods or medicines.

Patients can experience few symptoms intermittently or have disabling symptoms daily affecting multiple organ systems. Symptoms include, but are not limited to:

  • Skin: flushing, itching, rashes [including urticaria pigmentosa (UP), telangiectasia macularis eruptive perstans (TMEP)]
  • Gastrointestinal: Abdominal pain, bloating, nausea, diarrhea, vomiting, reflux (GERD)
  • Neurological: Brain fog, cognitive problems, anxiety/depression, tremors, headaches
  • Endocrine: Osteopenia, osteoporosis, bone lesions, bone pain
  • Cardiac: blood pressure changes with hypertension/hypotension, palpitations, fainting
  • Respiratory: nasal congestion, wheezing
  • Anaphylaxis

How are mast cell disorders diagnosed?

Patients can have many different, seemingly unrelated symptoms, and may visit multiple doctors seeking treatment. Frequently, it’s difficult to find a doctor who can “connect the dots.”

If you suspect you might have a mast cell disorder, a board-certified allergist or immunologist is a good place to start. Other specialists, depending on your symptoms, include gastroenterologists, dermatologists, hematologists and endocrinologists.

Diagnosis relies on urine and blood tests, including serum tryptase – a marker of mast cell burden or activation – both at a baseline level and during a mast cell reaction, and 24-hour urine collections for various mast cell mediators, including histamine and prostaglandin metabolites. Tissue biopsies for diagnosis may include a skin and/or bone marrow biopsy, endoscopy or colonoscopy of the gastrointestinal tract and specific mast cell stains. Select patients may need genetic tests. Bone density, bone scans and CT scans of the abdomen and chest may be necessary to assess mast cell infiltration or damage.

Mast cell disorders treatment options

Some symptoms can be controlled or eliminated by avoiding known triggers. In addition, patients may be treated with medications to block reactivity of the mast cells or the effects of mast cell mediators. These medications include H1 and H2 antihistamines, mast cell stabilizers (cromolyn sodium, ketotifen), leukotriene inhibitors such as montelukast, and possibly prostaglandin blockers (aspirin, only with direct supervision by a physician).

Aggressive disease may require treatment with interferon or chemotherapy.

Patient Resources

The Mastocytosis Society, Inc. (TMS) is a nonprofit organization dedicated to patients affected by mastocytosis and/or mast cell activation disorders, their families, caregivers and physicians through research, education and advocacy. TMS accepts donations to support mast cell disorder research, education and advocacy.

Mastokids supports families affected by pediatric mastocytosis

American Academy of Allergy, Asthma & Immunology


This article first appeared in the Summer 2014 issue of Allergy & Asthma Today magazine. It was written by Valerie Slee, RN, BSN and Susan Jennings, PhD of The Mastocytosis Society, Inc.