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The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 33

40. What is mastocytosis of childhood? Is mast cell disease different for children than adults?

Cutaneous mastocytosis in children is the most common form of mastocytosis. True systemic mastocytosis, in which the WHO criteria are met, is very rare in children.

In many ways, mastocytosis in children has huge differences from mastocytosis in adults. The exact reason for this is unclear. Because of how different the disease path can be for children, doctors and researchers sometimes refer it as mastocytosis of childhood. However, there is not officially a distinct diagnostic category.

Unlike in adults, mastocytosis in children is sometimes both benign and transient. Many kids have symptoms that either stay the same or improve as they get older. Many kids grow out of their mastocytosis. About 2/3 of children with cutaneous mastocytosis have no evidence of disease (no skin lesions or symptoms) by their late teen years or early adulthood. Many other children have improvement of symptoms and signs without completing growing out of their condition.

Children with mastocytosis often have some unusual things in their bone marrow biopsies. They often have clusters of mast cells and eosinophils with other cells in their bone marrow. However, the mast cells in those clusters are often normal mast cells and do not have the same markers we see in adults. Many of these children have more mast cells in their bone marrow biopsies than adults with mastocytosis. However, unless the biopsy shows true SM, it does not affect prognosis for the children. Children may have unusual things in their bone marrow biopsies but still go on to grow out of it.

The exception is if the child has true SM. Children with true SM do not grow out of their disease.

Children with mastocytosis often have symptoms that affect multiple organ systems, not just their skin. Abdominal pain and bone pain are often reported. Systemic symptoms do not tell us whether or not the child has SM or whether or not they will grow out of their disease.

An NIH study that included 105 children with mastocytosis found that children with normal baseline tryptase tests had negative bone marrow biopsies. It also found that a tryptase level elevated after anaphylaxis or a bad reaction did not signify that the child had SM. However, they did find that all children with SM had internal organ swelling. Most children with SM were positive for the CKIT D816V mutation.

There are no studies yet on the differences between adults and children with MCAS. There are enough anecdotal findings to suggest that children with MCAS do not grow out of their disease the way children with CM sometimes do.

For more detailed reading, please visit these posts:

Childhood mastocytosis: Update

Progression of mast cell diseases (Part 5)