Determining the Pathogenesis of Systemic Pediatric-Onset Mastocytosis

This study will evaluate children with mastocytosis, a disease of excessive mast cells in tissues such as skin and bone marrow, to identify the cause of the disease and describe its course. Mast cells can release chemicals that cause itching, blisters, flushing, bone pain, and abdominal pain. Usually, mastocytosis in children involves the skin only and is of limited duration. This study, however, will focus on children with more severe disease that more closely resembles adult-onset mastocytosis.

Patients up to 21 years of age with childhood-onset mastocytosis may be eligible for this study. Candidates must have one or more of the following abnormalities, which indicate severe disease: enlarged liver or spleen; diffuse skin involvement; history of gastrointestinal bleeding or peptic ulcer; bone marrow biopsy with abnormal mast cells either in number or shape; elevated blood levels of the enzyme tryptase; or abnormal hemoglobin, white blood cells, platelets, or clotting factors.

Participants will have a medical history and physical examination; various blood tests, including studies to identify genetic changes that are important in the growth, development, and functioning of human mast cells; and bone marrow aspiration and biopsy. For the bone marrow procedure, the skin over the hipbone and the outer surface of the bone itself are numbed with an injection of local anesthesia. Then, a special needle is inserted into the hipbone and about 2 tablespoons of bone marrow are drawn into a syringe. Another needle is then inserted through the first needle to collect a small piece of the bone marrow. Pain will be managed according to the individual patient s needs. Additional procedures, such as a gastroenterology consultation, colonoscopy to examine the colon, or computerized axial tomography (CT) or ultrasound of the abdomen to assess the liver and spleen, may be done if medically indicated. Standard medical treatment, including antihistamines for itching or steroids for abdominal cramping or diarrhea, will be recommended as appropriate.

Patients biologic parents may also be enrolled to provide a blood sample for genetic analysis and a bone marrow aspirate and biopsy for clinical and research purposes.

Patients will return to NIH once a year for follow-up evaluations until their disease is stable or until the 5-year study ends.

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