Differential Diagnosis for a 20-month-old Girl with Recurrent Fever and Cough

• Single Most Likely Diagnosis

  • Cystic Fibrosis (CF): The patient's recurrent episodes of fever and cough since early infancy, failure to thrive (indicated by being at the 5th percentile for weight), and physical examination findings such as mild clubbing and bilateral crackles, are highly suggestive of CF. The chest X-ray findings of streaky densities and mild hyperinflation also support this diagnosis.

• Other Likely Diagnoses

  • Recurrent Pneumonia: Given the patient's history of several similar episodes since infancy, recurrent pneumonia due to various pathogens is a consideration. However, the presence of clubbing and failure to thrive points towards a more chronic condition.
  • Bronchiectasis: This condition could explain the recurrent infections and physical findings, but it is less likely than CF given the age of onset and the constellation of symptoms.
  • Primary Ciliary Dyskinesia (PCD): Although less common, PCD could present with similar respiratory symptoms and situs inversus (not mentioned but often associated). The lack of specific diagnostic findings for PCD in the provided information makes CF a more likely diagnosis.

• Do Not Miss Diagnoses

  • Tuberculosis (TB): Given the patient's travel history to Finland (though TB is more common in other parts of the world), TB should be considered, especially with symptoms like fever, cough, and weight loss. It's crucial to rule out TB due to its public health implications and the need for specific treatment.
  • Immunodeficiency: Conditions like severe combined immunodeficiency (SCID) or other immunodeficiencies could present with recurrent infections. Although less likely given the specific pattern of illness, it's critical not to miss these diagnoses due to their significant impact on management and prognosis.
  • Foreign Body Aspiration: Though less likely in a 20-month-old without a clear history of aspiration, it should be considered, especially if there are focal findings on the chest X-ray.

• Rare Diagnoses

  • Alpha-1 Antitrypsin Deficiency: This genetic disorder can lead to lung disease in children, including symptoms similar to those presented. However, it is less common and typically associated with a family history of lung disease or liver disease.
  • Congenital Lung Anomalies: Conditions like congenital pulmonary airway malformation (CPAM) or bronchial atresia could present with recurrent infections but are less likely given the bilateral nature of the findings and the absence of specific diagnostic clues.
  • Interstitial Lung Disease: A broad category of rare diseases that affect the lung interstitium, which could present with similar symptoms but are less common in this age group and would require further diagnostic testing for confirmation.