What is the diagnosis for an 18-month-old boy with a history of eczema, presenting with poor appetite, failure to thrive, and selective eating habits, preferring pureed foods and refusing solid foods, with a weight percentile drop from 25th to 5th over 6 months?

Differential Diagnosis for an 18-month-old Boy with Poor Appetite

• Single most likely diagnosis:
  • Food selectivity or Avoidant/Restrictive Food Intake Disorder (ARFID): This diagnosis is likely due to the child's preference for pureed foods and refusal to eat solid foods, leading to significant weight gain issues. The child's normal development and absence of other symptoms support this diagnosis.
• Other Likely diagnoses:
  • Constipation: Although the child has daily soft stools, constipation can sometimes present with soft stools, and the child's refusal to eat fiber-rich foods like fruits and vegetables may contribute to constipation.
  • Gastroesophageal reflux disease (GERD): GERD can cause feeding difficulties and food refusal in children, although the absence of vomiting or diarrhea makes this less likely.
  • Sensory processing disorder: Some children with sensory processing issues may exhibit food selectivity, and the child's history of eczema may suggest a predisposition to sensory processing issues.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
  • Celiac disease: Although the child does not have typical symptoms like diarrhea or abdominal pain, celiac disease can present with failure to thrive and should be considered in any child with significant weight gain issues.
  • Inflammatory bowel disease (IBD): IBD can cause weight loss, failure to thrive, and feeding difficulties in children, and should be considered in the differential diagnosis.
  • Immunodeficiency: Immunodeficiencies like HIV or primary immunodeficiencies can cause failure to thrive and should be considered in any child with significant weight gain issues.
• Rare diagnoses:
  • Eosinophilic esophagitis: This condition can cause feeding difficulties and food refusal in children, although it is relatively rare.
  • Food protein-induced enterocolitis syndrome (FPIES): FPIES is a rare condition that can cause feeding difficulties and failure to thrive in children, although it typically presents with more severe symptoms like vomiting and diarrhea.