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Last updated Nov. 13, 2018

Approved by: Maulik P. Purohit MD, MPH

Mastocytosis is a rare disorder that results from excessive numbers of (often abnormal and elevated numbers of) mast cells in the skin and, rarely, in the organs.

What are other Names for this Condition? (Also known as/Synonyms)

  • Cutaneous Mastocytosis
  • Mast Cell Disease
  • Systemic Mastocytosis

What is Mastocytosis? (Definition/Background Information)

  • Mastocytosis is a rare disorder that results from excessive numbers of (often abnormal and elevated numbers of) mast cells in the skin and, rarely, in the organs
  • Mast cells, which reside in the connective tissue, store chemicals important to initializing the inflammatory and allergic responses. They also have important immune functions and can ingest (phagocytose) disease-causing microbes. Once activated, mast cells release chemicals including heparin, histamine, and serotonin. These stimulate the body’s inflammatory response
  • Infants are generally susceptible to the type affecting the skin (called Cutaneous Mastocytosis) and adult-onset of the systemic disease (called Systemic Mastocytosis) typically occurs in individuals aged 50-80 years
  • Smoking, exposure to radiation and industrial chemicals, viral infections, and chemotherapy are some known risk factors for Mastocytosis. Infancy is a risk factor for Pediatric Mastocytosis. Hence, avoiding exposure to industrial chemicals, smoking, etc. are some ways of preventing the condition
  • Mastocytosis is generally caused by a mutation in a protein termed C-KIT receptor, which resides on the surface of cells and binds to a factor (stem cell factor) that helps certain types of cells to grow
  • Mastocytosis of the skin (Cutaneous Mastocytosis) could cause rashes, blisters, and severe itching, while Systemic Mastocytosis could lead to symptoms such as weakness, joint and problems, pain in the abdomen, headaches, night sweats, breathing difficulties, and elevated heart rates. Uncontrollable inflammatory responses and tissue scarring are some complications that could arise from Mastocytosis
  • A physician could use an array of tests to check for this condition. The tests to diagnose Mastocytosis include a general physical examination, blood tests, skin and bone biopsies, x-rays, and genetic testing to detect C-KIT mutations
  • At this time, there are no standard treatment options for Mastocytosis. Generally, control of inflammatory response and therefore the symptoms is recommended, which involves anti-histamine treatment. In some cases, where the C-KIT protein is not mutated or if the mutation status is not known, those with Mastocytosis could be treated with a chemotherapy drug. Removing severely affected tissue might be a treatment option as well
  • Children and individuals suffering from Cutaneous or Skin Mastocytosis may recover over time. However, Mastocytosis in those with systemic forms, might progress to cancer

Who gets Mastocytosis? (Age and Sex Distribution)

  • Mastocytosis is a relatively rare disorder, with an estimated global prevalence of 1 in 20, 000 to 1 in 40,000
  • Children aged less than 6 months can develop Cutaneous Mastocytosis
  • Individuals aged 50-80 years usually develop Systemic Mastocytosis
  • Both men and women are equally susceptible to the condition
  • All racial and ethnic groups are prone to Mastocytosis

What are the Risk Factors for Mastocytosis? (Predisposing Factors)

The following are factors that are believed to increase one’s susceptibility to Mastocytosis:

  • Smoking
  • Exposure to radiation and industrial chemicals
  • Chemotherapy
  • In rare cases, viruses

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Mastocytosis? (Etiology)

The cause of Mastocytosis is usually genetic.

  • Specifically, it is a small change (mutation) in the region of DNA of a receptor called C-KIT. This receptor is responsible for stimulating mast cells to grow and divide (proliferate)
  • Mast cells that have defective C-KIT receptors are unable to respond to signals from their environment. Thus, they proliferate independently of external signals
  • The overabundance of these abnormal mast cells causes the inappropriate stimulation of the inflammatory response. This leads to the signs and symptoms of Mastocytosis
  • In some cases, Mastocytosis is caused by unknown factors 

What are the Signs and Symptoms of Mastocytosis?

The typical signs and symptoms of Mastocytosis include:

  • Skin conditions such as:
    • Blisters and hives (urticaria)
    • Discolored spots, especially in clusters
    • Thickened spots with an orange-peel texture
    • Severe itching (pruritus)
  • Systemic conditions such as:
    • Abdominal pain
    • Difficulty breathing
    • Rapid heart rate (tachycardia)
    • Headache 
  • Bone, joint, and muscle signs and symptoms such as:
    • Bone pain (ostealgia)
    • Joint pain (arthralgia)
    • Muscle pain (myalgia)
  • Nonspecific (constitutional) presentations such as:
    • Fatigue
    • Weight loss
    • Fever
    • Night sweats

How is Mastocytosis Diagnosed?

The following are some tests that may be used in the diagnosis of Mastocytosis:

  • Physical exam to detect skin abnormalities and comprehensive medical history evaluation
  • Blood smear to detect:
    • Increased numbers of mast cells
    • Abnormally-shaped mast cells
    • Reduced numbers of red blood cells (anemia)
    • Reduced numbers of platelets (thrombocytopenia)
  • Blood tests to detect:
    • Elevated lactate dehydrogenase levels
    • Elevated alkaline phosphatase levels
  • Radiographic tests to detect bone deficiencies
  • Bone marrow biopsy to detect increased cell numbers (hypercellularity)
  • Skin biopsy to detect:
    • Clusters of mast cells
    • Abnormally-shaped mast cells
  • Genetic tests to detect a KIT mutation

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Mastocytosis?

Following are complications that may arise from Mastocytosis:

  • Uncontrollable inflammatory and allergic reactions
  • Permanent tissue scarring

How is Mastocytosis Treated?

At the present time, there are no standard treatments available for Mastocytosis. The treatment options are dependent on the severity of the condition, as well as the patient’s health, and are usually geared towards symptom relief.

  • Since the disease involves inflammatory response, many patients are treated with antihistamines. Caution should be exercised while using non-steroidal anti-inflammatory medications such as Ibuprofen or naprosyn. These medicines could cause upset stomach, as well as release of histamines, which could cause severe and adverse reactions
  • Many patients may be advised to carry injectable epinephrine to overcome serious allergic reactions
  • In cases where the exact genetic cause is unknown or is not associated with C-KIT mutation, cytoreductive chemotherapy may be recommended. This is the treatment of Mastocytosis with US FDA-recommended chemotherapy drugs
  • Cytoreductive surgery may be an option for those with systemic forms of the condition. While surgery on the skin is considered relatively straightforward, this type of surgery for internal organs should be carefully considered and only performed by an experienced surgeon

How can Mastocytosis be Prevented?

Mastocytosis could potentially be avoided by:

  • Limiting exposure to radiation and industrial chemicals
  • Limiting chemotherapy
  • Avoiding smoking

What is the Prognosis of Mastocytosis? (Outcomes/Resolutions)

  • Cutaneous Mastocytosis in children is usually not life-threatening and the condition generally resolves before puberty
  • Systemic Mastocytosis can be aggressive and may progress to advanced stages such as cancer. In such cases, the prognosis may be several months

Additional and Relevant Useful Information for Mastocytosis:

Recently, it has been shown that the chemicals released by mast cells also affect the activities of the bone cells. These include bone-building osteoblasts and bone-digesting osteoclasts. Mast cells have been linked to stimulation of osteoclasts and inhibition of osteoblasts, resulting in bone deficiencies.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Oct. 29, 2015
Last updated: Nov. 13, 2018