Differential Diagnosis for a 20-month-old girl with recurrent fever and cough

• Single most likely diagnosis

  • B) Cystic fibrosis: This diagnosis is most likely due to 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 wheezing with bilateral crackles. The chest x-ray showing streaky densities and mild hyperinflation also supports this diagnosis.

• Other Likely diagnoses

  • A) α1-Antitrypsin deficiency: Although less common than cystic fibrosis, α1-Antitrypsin deficiency can present with similar respiratory symptoms, including recurrent infections and lung damage, which might be suggested by the streaky densities on the chest x-ray.
  • G) Pulmonary tuberculosis: Given the patient's travel history to Finland (though TB is more common in other parts of the world) and symptoms like fever, cough, and weight loss, TB should be considered, especially if there was exposure to someone with active TB.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)

  • F) Pulmonary hemorrhage: Although less likely given the chronic nature of symptoms, pulmonary hemorrhage can present with sudden worsening of respiratory status and could be life-threatening. It's essential to consider this in the differential, especially if there's a sudden change in the patient's condition.
  • E) Pulmonary aspergillosis: This fungal infection can cause severe disease in immunocompromised individuals or those with pre-existing lung disease. While less likely, it's crucial to consider due to its potential severity.

• Rare diagnoses

  • D) Pulmonary alveolar proteinosis: A rare condition characterized by the accumulation of surfactant-like protein and phospholipids in the alveoli, leading to respiratory symptoms. It's less likely but could be considered if other diagnoses are ruled out.
  • C) Pneumothorax: While pneumothorax can occur in the context of lung disease, the presentation typically involves acute onset of chest pain and shortness of breath, which doesn't perfectly match this patient's chronic symptoms and physical findings. However, it remains a possibility, especially if there's underlying lung disease.