Differential Diagnosis for Unilateral Periodic Rhinitis in a Young Child

• Single most likely diagnosis
  • Allergic rhinitis: This is the most common cause of periodic rhinitis in children, often triggered by allergens such as pollen, dust mites, or pet dander. Unilateral symptoms can occur if the allergen is more concentrated on one side of the nose.
• Other Likely diagnoses
  • Viral upper respiratory infection: Although typically bilateral, viral infections can sometimes cause unilateral symptoms, especially if one nasal passage is more affected than the other.
  • Anatomical obstruction (e.g., deviated septum, nasal polyp): These conditions can cause unilateral nasal congestion and rhinitis, especially if the obstruction is significant enough to affect nasal airflow.
  • Foreign body in the nose: Young children often insert small objects into their noses, which can cause unilateral rhinitis, discharge, and sometimes bleeding.
• Do Not Miss diagnoses
  • Nasal tumor (e.g., juvenile nasopharyngeal angiofibroma): Although rare, these tumors can cause unilateral nasal obstruction and rhinitis. Early detection is crucial for effective treatment.
  • Granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis): This is a rare autoimmune disorder that can cause destructive lesions in the nose and sinuses, leading to unilateral rhinitis and other symptoms.
• Rare diagnoses
  • Cystic fibrosis: This genetic disorder can cause chronic rhinitis and sinusitis, sometimes presenting unilaterally, although it is more commonly associated with bilateral symptoms.
  • Primary ciliary dyskinesia: A rare genetic disorder affecting the motility of cilia in the respiratory tract, leading to chronic rhinitis and sinusitis, which can be unilateral in some cases.