Differential Diagnosis for a 15-year-old Male with Cold-like Symptoms

Single Most Likely Diagnosis

• Viral Pharyngitis: This is the most likely diagnosis given the symptoms of sore throat, coughing, rhinorea, and congestion without fever, which are typical of a viral upper respiratory infection. The worsening of symptoms at night and upon waking is also consistent with viral pharyngitis.

Other Likely Diagnoses

• Allergic Rhinitis: The presence of rhinorea and congestion, especially if they are seasonal or triggered by specific allergens, could suggest allergic rhinitis. The sore throat could be secondary to postnasal drip.
• Acute Sinusitis: Although less likely without fever, acute sinusitis could present with similar symptoms, especially if the congestion and rhinorea are prominent and accompanied by facial pain or pressure.
• Infectious Mononucleosis (Mono): Although it often presents with fever, infectious mononucleosis can sometimes present without fever, especially early in the course. The sore throat, particularly if severe and accompanied by lymphadenopathy, could suggest this diagnosis.

Do Not Miss Diagnoses

• Strep Throat (Group A Beta-Hemolytic Streptococcus): Although the patient denies fever, strep throat can occasionally present without fever, especially in children. It's crucial to consider this diagnosis due to the potential for complications like rheumatic fever if left untreated.
• Peritonsillar Abscess: This is a complication of tonsillitis that can present with severe sore throat, often worse on one side, and can be life-threatening if not promptly treated.
• Epiglottitis: Although rare in the era of widespread vaccination against Haemophilus influenzae type b, epiglottitis is a medical emergency that can present with sore throat and respiratory distress.

Rare Diagnoses

• Lemierre's Syndrome: A rare condition characterized by a sore throat followed by neck pain and fever, due to a bacterial infection of the tonsils and subsequent thrombophlebitis of the internal jugular vein.
• Tuberculosis (TB): Although extremely rare in immunocompetent adolescents without exposure history, TB can present with chronic cough, sore throat, and systemic symptoms.
• Sarcoidosis: A systemic granulomatous disease that can rarely present with respiratory symptoms similar to those described, although it would typically be accompanied by other systemic symptoms or findings.