AN INFANT WITH HEREDITARY ALPHA TRYPTASEMIA AND ELEVATED INTESTINAL MAST CELLS IMPROVES WITH CYPROHEPTADINE TREATMENT

Abstract

<h3>Introduction</h3> Hereditary alpha tryptasemia (HaT) causes symptoms in multiple organ systems, including gastrointestinally. We present a patient with HaT who had chronic reflux and diarrhea that resolved with cyproheptadine treatment. Histology demonstrated increased numbers of mast cells within the duodenum and colon, further supporting the role of HaT in the pathophysiology of his symptoms. <h3>Case Description</h3> A 10-month-old boy with a history of premature birth at 33 weeks presented to allergy clinic for two episodes of intractable vomiting and lethargy after consuming oats. His parents also reported a history of severe reflux refractory to famotidine and intermittent loose stools. The patient's mother and two siblings have HaT confirmed via genetic testing. Laboratory evaluation revealed undetectable IgE to oat and elevated tryptase of 15.3 ng/mL, lending diagnoses of oat FPIES and likely HaT. Trials of cetirizine and omeprazole did not alleviate his symptoms. Workup for infectious or malabsorptive causes was unrevealing. He underwent esophagogastroduodenoscopy and colonoscopy with biopsy, which showed normal architecture without eosinophils. Immunostaining for CD117 (c-kit) and tryptase highlighted greater than 63 and 77 mast cells per high power field (HPF) within the duodenum and colon respectively. He was initiated on cyproheptadine 1 mg daily, as this had helped his sibling's similar symptoms, and had complete resolution of his reflux and loose stools. <h3>Discussion</h3> Increased numbers of mast cells in the intestinal mucosa may contribute to gastrointestinal symptoms in HaT, a finding not previously reported in pediatric literature. Cyproheptadine may be a useful treatment for patients with HaT who experience significant gastrointestinal symptoms.