Differential Diagnosis for Copious Nasal Discharge in a 9-Month-Old
Single Most Likely Diagnosis
- Viral Upper Respiratory Tract Infection (URTI): This is the most common cause of nasal discharge in infants, often presenting with other symptoms like cough, fever, and irritability. The high frequency of viral infections in this age group due to an immature immune system and frequent exposure to pathogens makes this the leading diagnosis.
Other Likely Diagnoses
- Allergic Rhinitis: Although less common in infants, allergic reactions to environmental allergens can cause nasal discharge. This is more likely if there's a family history of allergies or if the infant has been exposed to a new environment or allergen.
- Nasal Foreign Body: Infants often explore their environment by putting objects into their mouths, ears, and noses. A foreign body in the nose can cause unilateral purulent nasal discharge.
- Sinusitis: Bacterial sinusitis can occur in infants, especially after a viral URTI, and presents with nasal discharge, fever, and facial pain (though the latter might be difficult to assess in infants).
Do Not Miss Diagnoses
- Bacterial Meningitis: Although rare, bacterial meningitis is a life-threatening condition that can present with nonspecific symptoms in infants, including fever, irritability, and nasal discharge (in the case of meningococcal infection).
- Congenital Anomalies (e.g., Choanal Atresia): These are rare conditions that can cause nasal obstruction and discharge. Choanal atresia, for example, is a congenital blockage of the nasal passage that can lead to respiratory distress and nasal discharge.
Rare Diagnoses
- Cystic Fibrosis: This genetic disorder can lead to chronic respiratory infections and nasal polyps, causing persistent nasal discharge. It's rare but should be considered in infants with recurrent infections or failure to thrive.
- Immunodeficiency: Primary immunodeficiencies can predispose infants to recurrent and severe infections, including those causing nasal discharge. This would be considered in infants with a history of recurrent infections or infections with unusual organisms.
- Tumor (e.g., Nasal Glioma or Encephalocele): Rare congenital tumors can cause nasal obstruction and discharge. These conditions are extremely rare but can have significant implications if not diagnosed and treated properly.