A child was eventually diagnosed with systemic mastocytosis (SM) though he presented with none of the usual systemic symptoms, according to a case report recently published in Pediatrics.
“The case illustrates that, even in the absence of classic systemic symptoms, an index of suspicion for SM should be maintained, and highlights that peripheral testing for the c-KIT D816V mutation may represent a false negative,” the report’s authors said.
What is SM?
Systemic mastocytosis (SM) is a rare hematological disease characterized by mast cells that are overactive and accumulate in different parts of the body such as the bone marrow, liver, spleen, gastrointestinal tract and lymph nodes.
The case involved a 10-year-old boy with a yearslong history of cutaneous mastocytosis. Based on other individuals’ reports, the authors said that SM tends to present initially with isolated symptoms in children, followed by systemic symptoms months or years later.
Read more about SM testing and diagnosis
The boy’s case highlighted the importance of a high degree of clinical suspicion in making an accurate and timely diagnosis in this population.
SM is a rare diagnosis in the pediatric population, and it is mainly associated with other hematological neoplasms. Therefore, there are no clear guidelines on when to pursue a bone marrow biopsy to confirm a diagnosis.
“For pediatric patients with persistently elevated tryptase levels, particularly those on oral antihistamines, an index of suspicion for SM should be maintained, and consideration should be given to bone marrow biopsy even with a negative peripheral test,” the report authors said.
The boy had progressive worsening of his symptoms in preceding months and was referred to hematology, allergy and immunology services.
Up to that point, the patient had not experienced any gastrointestinal, cardiovascular or neurological symptoms. Six years after his initial diagnosis, the patient experienced one or two daily episodes of flushing and itching. He also presented with systemic symptoms in the form of abdominal pain and fatigue but had not undergone genetic testing.
Two years later, his tryptase levels continued to rise despite adhering to antihistamine treatment. In light of persistent dermatological and abdominal symptoms, coupled with a new onset of respiratory symptoms and two anaphylaxis episodes, he underwent testing for c-KIT D816V mutations, which turned out negative.
Despite the negative genetic tests, his physicians elected to perform a bone marrow biopsy, which revealed mastocytic infiltration consistent with SM. Despite exploring advanced therapeutic options such as omalizumab, the patient persisted with antihistamine treatment as monotherapy as his parents preferred.
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