Differential Diagnosis for 9-Month-Old with Wheezing, Productive Cough, Greasy Stool, and Prior Meconium Ileus

• Single Most Likely Diagnosis

  • Cystic Fibrosis (CF): This condition is highly suggested by the combination of respiratory symptoms (wheezing and productive cough), gastrointestinal symptoms (greasy stools indicating malabsorption), and a history of meconium ileus, which is a classic presentation for CF in newborns. The failure to gain weight also aligns with CF due to malabsorption.

• Other Likely Diagnoses

  • Chronic Infections or Bronchiolitis: Repeated infections could lead to wheezing and cough, and if associated with malabsorption or pancreatic insufficiency, could mimic some aspects of CF.
  • Gastroesophageal Reflux Disease (GERD): Could cause wheezing and cough due to aspiration, and if severe, might lead to failure to thrive, but greasy stools are less commonly associated with GERD.
  • Primary Ciliary Dyskinesia: A condition that affects the cilia, leading to chronic respiratory infections and could potentially cause gastrointestinal symptoms, though greasy stools are not a hallmark.

• Do Not Miss Diagnoses

  • Congenital Heart Disease: Although less directly related to the gastrointestinal symptoms, severe congenital heart disease can cause failure to thrive and respiratory symptoms due to heart failure. It's crucial to rule out due to its high mortality if untreated.
  • Immunodeficiency: Certain immunodeficiencies can present with recurrent infections, failure to thrive, and potentially gastrointestinal symptoms, making it critical not to miss.

• Rare Diagnoses

  • Shwachman-Diamond Syndrome: A rare condition characterized by exocrine pancreatic insufficiency, bone marrow dysfunction, and skeletal abnormalities, which could explain some of the symptoms but is much less common than CF.
  • Pearson Syndrome: A rare mitochondrial disorder that affects multiple systems, including the pancreas, which could lead to similar gastrointestinal and failure to thrive symptoms, but is extremely rare and typically presents with more systemic involvement.
  • Congenital Enteropathy: A group of rare disorders affecting the intestine, leading to malabsorption, which could explain the greasy stools and failure to thrive but would not directly account for the respiratory symptoms without additional complications.