Mast cell diseases occur when mast cells, a type of white blood cell, build up too much or are overly active. Mast cells are important for our immune system, but when there are too many or they are overactive, they can cause health problems. This includes mastocytosis and mast cell activation syndrome (MCAS).
It is common for people with mast cell diseases to have skin symptoms. These may include:
- raised bumps or welts, called urticaria (hives), that come and go;
- redness of the skin in people with fair skin
- itch, called pruritis;
- flat brown or pink skin lesions, of varying sizes, consisting of clustered mast cells (called mastocytomas).
The symptoms may present differently depending on the color of your skin. Hives on darker skin color may have the same color as the surrounding skin or have a reddish hue. The redness may not be as apparent.
Many healthcare providers are trained to diagnose skin symptoms linked to mast cell disease based on redness on fair skin. But skin symptoms for people of color appear differently in people with darker skin tones. They may appear as dark brown, purple, tan or gray on black or brown skin.
When healthcare providers do not know how mast cell disease looks in people of color, it can lead to a misdiagnosis or a missed diagnosis. It’s important for healthcare providers to know what to look for when diagnosing mast cell disease symptoms in skin of color.
Are mast cell disease symptoms different in skin of color?
Mast cell disease symptoms on the skin may vary depending on the skin color. When normal mast cells are activated or abnormal mast cells rise in numbers, they can release chemicals such as histamine, prostaglandin or leukotriene metabolites. Symptoms may include hives on the skin.The condition is a clonal mast cell disorder known as cutaneous mastocytosis, also called urticaria pigmentosa.
Urticaria on black and brown skin may have the same color as the surrounding skin. It may have a reddish hue, although this may not readily appear on darker skin. In addition to common symptoms such as itching, swelling and flushing, there may be skin discoloration.
On lighter skin, skin discoloration from cutaneous mastocytosis is often described as red. In people of color, this skin discoloration may appear purplish, brown, tan, or gray. The symptoms might not be as easy to see in darker skin. This can make it harder to know how serious the condition is. Without a proper diagnosis and appropriate treatment, the rashes of cutaneous mastocytosis or urticaria pigmentosa can take months to resolve.
In addition, people with darker skin may develop thicker scars, called keloids, from their skin symptoms. These may occur after a biopsy or due to constant scratching of the affected skin.
Other signs and symptoms linked to clonal mast cell disease may involve other body systems:
- Stomach: Abdominal pain, nausea, vomiting, diarrhea, heartburn
- Brain: Feeling confused, trouble thinking, feeling anxious or sad, shaking, headaches
- Bones: Weak bones, bone pain
- Heart: Blood pressure changes, heart racing, fainting
- Breathing: Shortness of breath, wheezing
Mast cell disease can also lead to anaphylaxis, a severe or life-threatening reaction. This occurs when mast cells are activated by substances, including allergens. The triggers may include food, venom from stinging insects or physical triggers, such as heat, direct pressure (such as scratching), or even exercise. It can cause the sudden, rapid release of mast cell mediators such as histamine.
How are mast cell diseases diagnosed in skin of color?
What specialists can diagnose mast cell disease? To start, you can see an allergist and immunologist. A dermatologist can diagnose cutaneous mastocytosis or urticaria pigmentosa. Doctors may first look for skin lesions. In people of color, this means searching for rashes that appear purple, brown, tan or gray. If the doctor gently strokes the lesion and hives develop around it, this is called a Darier’s sign. This is a sign of cutaneous mastocytosis.
Doctors may conduct blood and urine tests to search for markers of abnormal or overactive mast cells. These tests may be done at baseline and during or after a reaction. They may recommend genetic tests that look for abnormal mast cells. In particular, a mutation called D816 in the C-kit protein is found in more than 90% of people with a form of mastocytosis.
Doctors may also conduct a biopsy to collect tissue from skin or the gastrointestinal tract. They may want to do a bone marrow biopsy. In a biopsy, the doctor examines tissue using a microscope, searching for signs of abnormal mast cells.
If there are signs of clonal mast cell disease such as systemic mastocytosis, the doctor may order radiology studies. These assess the burden of disease of abnormal or atypical mast cells.
Why are mast cell diseases harder to diagnose in skin of color?
For many years, medical training and research studies focused on the redness of lesions on lighter skin. This means many healthcare providers were not trained to look for skin discoloration in people with darker skin. It has resulted in misdiagnosis and delayed diagnosis of clonal mast cell disorders affecting people of color.
There is a significant need for more research focused on mast cell disease in people of color. This will help healthcare providers better understand what mast cell disease symptoms to look for in racial and ethnic groups. This, in turn, may lend to the development of tailored approaches for diagnosis and treatments in people with darker skin.
It’s important to educate communities of color about clonal mast cell disease. Encourage participation in research. This can help speed up diagnosis and treatment of this disease.
How are mast cell diseases treated in skin of color?
Mast cell disease treatment is based on a patient’s signs and symptoms, regardless of skin color. There is no cure for mast cell disease, but there are medications that can help stop or relieve symptoms. Treatment will depend on the type of mast cell disease and the severity of symptoms.
Racial and ethnic groups may respond differently to medications for mast cell disease. Doctors should personalize treatment when possible. Some people of color may have less access to healthcare, which can affect their treatment.
Medications may include:
- H1 and H2 antihistamines
- Topical corticosteroids to treat skin symptoms
- Mast cell stabilizers, such as cromolyn or ketotifen
- Leukotriene blockers
- Aspirin (under supervision of a healthcare provider)
- Omalizumab, an anti-immunoglobulin E (IgE) biologic medication that can block the release of histamine
- Tyrosine kinase inhibitors to treat aggressive systemic mastocytosis, both advanced and non-advanced forms
Advanced forms of systemic mastocytosis – such as mast cell leukemia or mast cell sarcoma – may require chemotherapy or a bone marrow transplant.
Some people with mast cell disease are at risk for anaphylaxis, a severe allergic reaction affecting two or more organ systems. If not treated promptly, anaphylaxis can be fatal if not treated. Epinephrine is the only medicine that can treat anaphylaxis. Using epinephrine to treat anaphylaxis is essential to protect against life-threatening symptoms.
People with mastocytosis or MCAS should talk with their doctor developing a written action plan. This action plan can detail what to do in case of mast cell activation symptoms.
What are different types of mast cell disorders in people of color?
The two most common types of mast cell diseases are mastocytosis and mast cell activation syndrome. Both can involve skin symptoms. These symptoms may appear differently in skin of color.
Mastocytosis
Mastocytosis is a rare type of mast cell disease. Fewer than 32,000 cases are reported in the United States. It is a condition in which there is an excess amount of mast cells in the body. They may build up in the skin, bone marrow, and/or digestive system, including the liver. They may also build up in lymph nodes.
When there’s a buildup of mast cells on the skin, it can cause cutaneous mastocytosis such as urticaria pigmentosa. The condition can appear in any age group but it is more common in children than adults. If the excessive mast cells start to release chemical mediators such as histamine, this can lead to an aggressive, itchy skin disorder. Symptoms may involve localized itch, especially near clusters of abnormal mast cells (called mastocytomas), or a more widespread itch.
On light skin, mastocytosis skin symptoms are often reddish. For mastocytosis in people of color, the skin symptoms may appear as the same skin color or more purplish, brown, tan or gray.
In systemic mastocytosis patients, mast cells build up in internal organs. These organs may include bone marrow, liver, spleen or the digestive system. This can cause skin symptoms, nausea, vomiting, diarrhea, intestinal cramping, bone pain and bone fractures. Severe cases can lead to anaphylactic shock or organ failure. Systemic mastocytosis is more common in adult patients.
Visit our Mastocytosis webpage to learn about treatment options
Mast cell activation syndrome (MCAS)
Mast cell activation syndrome is another rare type of mast cell disease. It occurs when mast cells become overactive and release too many chemicals such as histamine. This leads to a host of episodic symptoms. These may include nausea, itchy skin, abdominal cramping, diarrhea, bladder pain, rapid heart rate, low blood pressure, and/or irregular heartbeat (called arrhythmia).
People with MCAS may have frequent allergy symptoms or more allergic diseases. They may be more at risk for anaphylaxis.
MCAS symptoms are sometimes vague, making the disease hard to diagnose. They may involve symptoms of the skin that appear as atopic dermatitis or chronic urticaria. They may involve heart or gastrointestinal disorders, primary immune diseases, infections, and neurologic or psychiatric disorders.
MCAS can be associated with systemic mastocytosis, an immunoglobulin E (IgE) allergic reaction (from food, insect venom or medications) or physical triggers that cause skin hives. The triggers may include heat, friction or vibration (such as from a lawnmower), pressure on the skin (such as from scratching), exercise, or sun exposure.
Visit our Mast Cell Activation Syndrome webpage to learn about treatment options.
Reviewed by:
Anne Maitland, MD, FACAAI, is director of Allergy & Immunology Services at the Metrodora Institute. She previously served as assistant professor in the Department of Medicine, Allergy & Clinical Immunology, at Icahn School of Medicine at Mount Sinai in New York City. Dr. Maitland is very active in increasing awareness of immune-mediated disorders. She is also involved with research to continually improve the treatment of allergies, asthma and recurrent infections.
Supported by:
