What are the signs of infection for a lesion in the posterior pharynx (back of the throat)?

Signs of Infection for a Posterior Pharyngeal Lesion

For a lesion in the back of the throat, the key signs of infection include purulent drainage, fever, severe odynophagia (painful swallowing), muffled voice, drooling, tonsillar exudates, tender cervical lymphadenopathy, and tonsillar asymmetry or enlargement. 1

Confirmatory Signs of Infection

The following findings definitively indicate infection and warrant urgent evaluation:

• Purulent drainage from or around the lesion is a confirmatory sign of active infection 2
• Muffled voice (also called "hot potato voice") strongly suggests deep space infection such as peritonsillar or parapharyngeal abscess 1
• Drooling indicates severe pain with swallowing or airway compromise from infection 1
• Tonsillar asymmetry with one tonsil pushed medially suggests peritonsillar abscess 2

Suggestive Signs of Infection

These clinical findings raise suspicion for infection but are not definitive:

• Fever is common with bacterial infections, though its absence does not rule out serious infection like peritonsillar abscess 1
• Severe odynophagia (pain with swallowing) that limits oral intake 1
• Tonsillopharyngeal exudates (white or yellow patches on tonsils or pharynx) suggest bacterial infection, particularly Group A Streptococcus 2
• Tender anterior cervical lymphadenopathy indicates regional lymph node response to infection 2
• Erythema (redness) and swelling of the posterior pharynx or tonsils 2
• Soft palate petechiae (small red spots) suggest streptococcal infection 2

Red Flag Signs Requiring Urgent Evaluation

Certain findings indicate potentially life-threatening infections that require immediate specialist referral:

• Difficulty swallowing with drooling suggests impending airway obstruction 2, 1
• Neck tenderness or swelling may indicate deep space infection or Lemierre syndrome 2
• New-onset snoring with bilateral tonsillar enlargement indicates acute upper airway obstruction 1
• Severe pharyngitis in adolescents/young adults should raise suspicion for Fusobacterium necrophorum infection and Lemierre syndrome 2, 1
• Trismus (inability to open mouth fully) suggests peritonsillar abscess 1

Important Clinical Pitfalls

Do not be falsely reassured by the absence of fever—peritonsillar abscess and severe airway obstruction can occur without fever 1. A nontender neck mass is actually MORE suspicious for malignancy than a tender one, so tenderness with a posterior pharyngeal lesion suggests infection rather than cancer 2.

Distinguishing Bacterial from Viral Infection

Viral infections typically present with:

• Cough, rhinorrhea, hoarseness, or conjunctivitis 2, 3
• Oral ulcers or vesicles 2
• Diarrhea 2

Bacterial infections (particularly Group A Streptococcus) typically present with:

• Sudden-onset severe sore throat WITHOUT cough 2, 3
• Tonsillar exudates 2
• Scarlatiniform rash 2
• Palatal petechiae 2

When to Obtain Imaging

CT scan with contrast is recommended if peritonsillar or parapharyngeal abscess is suspected based on muffled voice, drooling, severe odynophagia, or tonsillar asymmetry 1. Delaying imaging when deep space infection is suspected is not recommended 1.