Pediatric Hypereosinophilic Syndrome (HES) Differs From Adult HES

Purpose of the Study. To highlight specific differences between pediatric and adult patients with hypereosinophilic syndrome (HES). Study Population. The case report involved a 15-year-old male who presented with abdominal pain, diarrhea, and a 10-lb weight loss. Colonoscopy revealed colitis. A nonproductive cough, night sweats, and a diffuse pruritic, papular rash developed. His initial absolute eosinophil count was 1890/mm3 (reference: <400/mm3), which increased to 52 000/mm3. Additional laboratory studies included: immunoglobulin E, 8561 U/mL (7–110 U/mL); alkaline phosphatase, 1149 U/mL (reference: 50–280 U/mL); γ-glutamyl transpeptidase, 193 (reference: 0–50 U/mL); and serum tryptase, 4.7 μg/L (reference: 1.9–13.5 μg/L). Ultrasound of the liver revealed an abnormal parenchymal pattern with dilated bile ducts. Molecular analysis of the patient’s peripheral blood for the Fip1-like-1 platelet-derived growth factor receptor α chain (FIP1L1-PDGFRA) fusion tyrosine kinase associated with HES in adults was negative. Open lung biopsy revealed patchy interstitial and intra-alveolar inflammation with a predominance of eosinophils. A skin biopsy showed acute neutrophilic folliculitis with perivascular dermatitis with eosinophils. Bone marrow biopsy demonstrated a hypercellular marrow with predominantly eosinophils, which is consistent with idiopathic HES. Methods. The investigators compared this case report of pediatric HES and additional published cases of pediatric and adult patients with HES. Results. Pediatric HES has only a slight male predominance (55.3% male vs 44.7% female), whereas adult HES is reported to be more common among males than females, with a ratio of 9 to 1. In adults, the frequencies of symptoms found on presentation are: fatigue (26%), cough (24%), dyspnea (16%), rash (12%), and fever (12%). Fever (58.8%), arthralgias (23%), and rash (23.5%) were more common in pediatric cases. As with adults, involvement of the cardiovascular system is the major source of morbidity and mortality. Pediatric HES is commonly associated with chromosomal abnormalities, and in ∼40% of the cases, it has been associated with acute leukemia. As opposed to the vast majority of adult HES cases, no pediatric case with the FIP1L1-PDGFRA fusion gene has been reported. Conclusion. There are several distinct features of pediatric, compared with adult, HES. Reviewer Comments. Most of the published information on the HES has focused on adult patients. This report compares a pediatric case report of HES and a review of published pediatric cases of this condition to adult patients with this syndrome. This is an insightful clinical report that should be useful in the overall workup of pediatric patients who present with dramatic eosinophilia (>1500/mm3) for >6 months’ duration without other known causes of eosinophilia and who have evidence of organ involvement that might be attributable to HES.