Differential Diagnosis for Pharyngitis

When considering the differential diagnosis for pharyngitis, it's crucial to categorize potential causes based on their likelihood and the severity of their consequences if missed. Here's a structured approach:

• Single Most Likely Diagnosis

  • Viral pharyngitis: This is the most common cause of pharyngitis, often resulting from viruses such as rhinovirus, coronavirus, adenovirus, and others. The justification for this being the single most likely diagnosis lies in its high prevalence and the fact that most cases of pharyngitis are viral in nature.

• Other Likely Diagnoses

  • Streptococcal pharyngitis (Group A beta-hemolytic streptococcus): This bacterial infection is a common cause of pharyngitis, especially in children and young adults. It's justified as an other likely diagnosis due to its significant prevalence and the need for specific antibiotic treatment to prevent complications.
  • Infectious mononucleosis (caused by Epstein-Barr virus): This condition often presents with sore throat, fever, and lymphadenopathy, making it a likely consideration in the differential diagnosis for pharyngitis, particularly in adolescents and young adults.

• Do Not Miss Diagnoses

  • Epiglottitis: Although rare, this condition is potentially life-threatening due to the risk of airway obstruction. It's crucial to consider epiglottitis, especially in adults and in the context of severe symptoms or difficulty swallowing.
  • Lemierre's syndrome: This is a rare but serious condition characterized by pharyngitis followed by a septic thrombophlebitis of the internal jugular vein, typically caused by Fusobacterium necrophorum. The potential for severe complications justifies its inclusion as a "do not miss" diagnosis.
  • Diphtheria: While rare in areas with high vaccination coverage, diphtheria can cause severe pharyngitis and is potentially life-threatening, making it essential not to miss this diagnosis, especially in unvaccinated individuals or those traveling from areas where diphtheria is common.

• Rare Diagnoses

  • Gonococcal pharyngitis: Caused by Neisseria gonorrhoeae, this condition is more common in sexually active individuals and can be asymptomatic or present with mild symptoms.
  • Tuberculous pharyngitis: This is a rare form of tuberculosis that affects the pharynx, more commonly seen in immunocompromised individuals or those from areas with high TB prevalence.
  • Syphilitic pharyngitis: Caused by Treponema pallidum, this condition is a rare manifestation of primary syphilis and should be considered in sexually active individuals with risk factors for sexually transmitted infections.