Mastocytosis is a rare condition where an excessive amount of mast cells gather in the organs and tissues of the body. It can affect the skin, lymph nodes, bone marrow, and other organ systems.
Mast cells are essential to the immune system and release histamine in response to allergens. However, mastocytosis can occur when mast cells accumulate in excess.
Mastocytosis can increase a person’s risk of a severe allergic reaction called anaphylaxis. It can also cause symptoms such as rashes, bone and muscle pain, and digestive issues. Sometimes, the condition can progress to leukemia.
This article discusses mastocytosis in more detail, including symptoms, causes, diagnosis, and treatment. It also considers some possible complications.
Mastocytosis is a rare disorder in which excessive numbers of mast cells gather in tissues in the body.
Mast cells develop in the bone marrow, the spongy tissue inside some bones. When they detect the presence of allergens — substances that cause an allergic reaction — mast cells release histamine and other chemicals.
Histamine causes blood vessels to enlarge, which can lead to itching and swelling in the skin. It can also cause the airways to narrow and trigger mucus buildup.
There are two main types of mastocytosis: cutaneous and systemic. Cutaneous occurs in the skin, and systemic develops in other bodily tissue.
The symptoms vary depending on the type of mastocytosis a person has.
Symptoms of cutaneous mastocytosis can include:
- lesions such as spots or bumps on the skin
- itchy skin
- small, flat, discolored areas of skin
- unusual pigmentation
- blistering of the skin
The severity of a person’s symptoms can depend on the subtype of systemic mastocytosis a person has.
There are three main subtypes of systemic mastocytosis:
- Indolent systemic mastocytosis: This accounts for about 90% of adult cases of systemic mastocytosis and causes mild to moderate symptoms.
- Aggressive mastocytosis: Mast cells multiply in organs, causing more severe, wide-ranging symptoms in this subtype.
- Systemic mastocytosis with associated blood disease: In this subtype, other conditions that affect the blood, such as chronic leukemia, can co-occur.
Generally, symptoms of systemic mastocytosis include:
Researchers believe a change in the KIT gene causes mastocytosis. The gene mutation is typically random and occurs without a family history.
The change in the KIT gene makes the mast cells more responsive to the effects of a protein called stem cell factor (SCF). SCF proteins are essential in stimulating the production of various cells inside the bone marrow, including blood and mast cells.
The higher sensitivity of the mast cells to SCF means the body produces more mast cells than usual in response.
Still, scientists do not fully understand the causes of mastocytosis and do not know exactly why the gene mutation occurs.
A doctor will diagnose cutaneous and systemic mastocytosis in different ways. To diagnose cutaneous mastocytosis, a doctor will usually:
- perform a physical examination of the skin
- rub the areas of the skin where the condition is present to check for inflammation, discoloration, and itching
- order a skin biopsy, which involves taking a small sample of tissue for laboratory analysis
To diagnose systemic mastocytosis, a doctor may perform:
There is no cure for mastocytosis, but treatment can help to relieve and manage symptoms. Sometimes, a person may not require treatment.
Treatment options can vary and depend on many factors, including the type of mastocytosis a person has and the severity of their symptoms.
A doctor may prescribe medications for mastocytosis, such as:
- Antihistamines: These block the effects of histamine. People often use antihistamines to treat allergic conditions, such as pollen allergies.
- Midostaurin (Rydapt): This works by slowing the growth of mast cells, which can relieve the condition’s symptoms. However, it may cause side effects, including headaches, diarrhea, and vomiting.
- Corticosteroids: Oral or topical corticosteroids can help reduce inflammation. Both can cause side effects, including mood changes, weight gain, and insomnia.
- Interferon alpha: This is a drug that doctors typically use to help treat cancer. Interferon alpha may also be effective as a treatment in aggressive mastocytosis, as it reduces mast cell production. The medication may cause side effects, such as flu-like symptoms.
- Calcium supplements and bisphosphates: A doctor may suggest a person take calcium and bisphosphates to help strengthen bones, as mastocytosis
can causebones to weaken.
Treatment may also include a type of light therapy called psoralen plus ultraviolet A (PUVA), which can reduce severe symptoms of cutaneous mastocytosis. PUVA involves taking a medication — called psoralen — to make the skin more receptive to the effects of UV and then exposing the affected skin to UVA light.
Doctors associate mastocytosis with
- non-Hodgkin’s lymphoma
- monoclonal gammopathy
- hairy cell leukemia
- recurrent anaphylaxis
Aggressive systemic mastocytosis can lead to complications such as:
- changes in memory and cognition
Mast cells, which release histamine in response to allergens, are essential to the body’s immune response. However, mastocytosis can occur when mast cells accumulate excessively in the body. The condition is typically due to a genetic mutation in the KIT gene.
Cutaneous mastocytosis affects the skin and can cause symptoms such as itching and rashes. Systemic mastocytosis affects other organs and tissues.
Serious complications, such as osteoporosis, anaphylaxis, and leukemia, can occur in people with mastocytosis. Doctors cannot cure the condition, but treatment can help manage the symptoms.