Children with mastocytosisMastocytosis Rare disease caused by the buildup of mast cells. Cutaneous mastocytosis primarily affects the skin and is more common in children, while systemic mastocytosis affects internal organs and is more common in adults. generally have the cutaneous form of the disease and a favorable outlook, though a small subset may later develop systemic mastocytosis (SM), according to a study published recently in Frontiers in Cell and Developmental Biology.
The study showed that while most pediatric cases remain confined to the skin, some share genetic features with adult SM, including c-KIT mutations, underscoring the need for long-term monitoring.
“Until now, significant correlations between genetic status, as well as the immunophenotype of [mast cells] in the skin, the disease phenotype and prognostication in pediatric mastocytosis have not been established,” the study’s authors explained.
Analysis included 36 patients diagnosed between 1997 and 2021. All initially had cutaneous mastocytosis, meaning disease limited to the skin rather than SM. The most common form was maculopapular cutaneous mastocytosis (55%), followed by diffuse cutaneous mastocytosis (28%) and mastocytoma (17%). Skin lesions typically appeared early, with a median onset of 4.7 months, and 69% developed symptoms within the first year of life.
Read more about the causes and risk factors of SM
Despite early onset, progression to SM was uncommon. Two patients (6%), both with maculopapular disease, later developed indolent SMIndolent SM A subtype of nonadvanced SM caused by the abnormal accumulation of mast cells in the bone marrow and other organs. Indolent SM accounts for around 90% of SM cases. at ages 25 and 38, occurring 10 and 20 years after initial symptoms. These findings suggest that while pediatric disease is usually limited to the skin, late progression remains possible, particularly in those diagnosed closer to adolescence.
Genetic testing revealed that 35% of children carried c-KIT mutations, including the D816V variant commonly seen in adult SM. This mutation was identified in four patients using a technique called reverse transcription-polymerase chain reaction, which proved more sensitive than next-generation sequencing for detecting this specific change.
However, next-generation sequencing identified additional mutations, including both known and previously unreported variants across genes such as ASXL1, JAK2, TET2 and others. Overall, 59% of those tested with sequencing had at least one mutation.
For patients, one of the most important findings is that the disease often improves. Nine of 36 children (25%) experienced complete disappearance of skin lesions after a median of 25 months, with some resolving years later. Lower tryptaseTryptase A protein enzyme that is primarily produced by mast cells and stored in small pockets within the cells, known as granules. High levels of tryptase are a key indicator of SM. levels at diagnosis were linked to a higher likelihood of remission. Notably, none of the patients required hospitalization or intensive care, and symptoms were typically managed with medications such as antihistaminesAntihistamines Medications that block the effects of histamine, the chemical found in mast cells that is responsible for many of the symptoms of SM, as well as many allergic reactions..
These results reinforce that pediatric mastocytosis, even though biologically related to SM, usually follows a milder course. However, the presence of SM-associated mutations and rare progression cases highlight the importance of ongoing follow-up. For patients and families, this means balancing reassurance with awareness, as most children will improve, but careful monitoring can help detect the uncommon transition to systemic disease.
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