Aggressive systemic mastocytosis (SM) in newborns is incredibly rare, with only a handful of cases ever reported worldwide. Now, a new case study from New Zealand published in the journal Pediatric Dermatology adds to this limited record, highlighting both the diagnostic challenges and the urgent need for greater awareness.
Mastocytosis occurs when the body produces too many mast cells, immune cells that fight infections and trigger allergic reactions. In most children, the disease presents as cutaneous mastocytosis and mainly affects the skin. In rare cases, mast cells spread to organs such as the liver, spleen and bone marrow, creating systemic disease.
In a systematic review of nearly 1,800 pediatric cases reviewed globally, only 3% of patients showed systemic involvement. Neonatal cases with the aggressive SM subtype are rarer still, with just eight published cases before this recent report.
Learn more about SM causes and risk factors
The case study involved a baby girl born prematurely at 33 weeks. Before birth, ultrasound scans revealed complications like fluid buildup throughout her body and enlarged organs. At birth, she had widespread skin lesions, liver and spleen enlargement and abnormal bloodwork.
A series of biopsies and genetic testing confirmed a diagnosis of aggressive systemic mastocytosis. Her doctors identified a mutation in the KIT D816V gene, a hallmark of the disease that causes mast cells to grow uncontrollably.
Doctors initially managed the baby’s symptoms with topical therapies, but after several weeks transitioned to oral midostaurin to treat the condition systemically. She initially entered remission but later experienced a flare at six months, underscoring how unpredictable the condition can be. At nine months, she entered remission again, and the report’s authors said she has remained in stable in this state to date.
Because neonatal aggressive SM is so rare, there are no established guidelines for treatment, and physicians must rely on individual case reports like this one to help inform care.
The authors state that this report “highlights the successful use of midostaurin as a well-tolerated and effective treatment option in this population.” However, they note that “further studies are needed to establish long-term safety, optimal treatment duration and to explore emerging therapies like avapritinib in pediatric patients.”
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