The exact cause of mastocytosis is unknown.
Mast cells are essential components of the inflammatory process. The mast cells may be stimulated by injury, the binding of immunoglobulin E (IgE) to receptors or by activated complement-dependent mechanisms.
Mast cells express FcεRI, a high-affinity receptor for IgE. When this receptor binds to IgE, it is irreversible. As a result, the mast cells become coated with IgE. Then, IgE is produced by B-cells in the immune system.
When an allergic reaction occurs, the allergen binds to IgE, and then mast cells are subsequently activated. It appears that mast cells are activated after two or more IgE molecules bind together (crosslinking). This process, known as IgE-mediated mast cell degranulation, triggers the release of granules and hormonal mediators into the interstitium.
Cutaneous mastocytosis (urticaria pigmentosa): Common symptoms include, facial flushing, brownish lesions on the skin, as well as welt, hive or blister formation when lesions are scratched or rubbed. In severe cases, diarrhea, increased heartbeat, headache and fainting may also occur.
Mastocytoma: Mastocytoma is usually present at birth or in early childhood. One or more red, pink or yellow bumps can appear anywhere on the skin. Rubbing or scratching the affected area causes mastocytomas to redden, swell and sometimes blister. Occasionally, patients experience flushing when the mast cells release chemicals like histamine.
Systemic mastocytosis: Since systemic mastocytosis may affect different areas of the body, symptoms may be related to the hematopoietic system, the gastrointestinal system, the skin and the immune system. Common symptoms include, abdominal pain, hives, rash, anaphylaxis, inflamed esophagus, changes in blood pressure, intestinal cramping, bloating, bone pain, itching, chest pain, liver problems, cognitive difficulties, malabsorption, degenerative disc disease, migraine headaches, diarrhea, muscle pain, dizziness, lightheadedness, nausea, osteoporosis, osteopenia, fatigue, peripheral neuropathy, paresthesias, flushing, rapid heart rate, gastroesophageal reflux, vomiting and hematological abnormalities.
Biopsy: A qualified healthcare provider may take a tissue biopsy from an organ (like the bone marrow) or the skin, to determine whether the patient has systemic mastocytosis. The tissue sample is analyzed in the lab to determine whether there is an increase in the number of mast cells.
Blood test: A physician may perform a blood test to confirm a diagnosis. A small sample of blood is taken and analyzed under a microscope to determine whether there are an increased number of mast cells in the blood.
Urine test: A urine test may be conducted. Individuals with urticaria pigmentosa will usually have elevated levels of histamine in their urine.