In the outpatient setting, evaluation of sore throat is one of the most common reasons adults and children seek medical care. Approximately 2 million annual emergency department (ED) visits are caused by acute pharyngitis and tonsillitis.¹ Although most of these cases are relatively mild, ED and urgent care providers must be attentive to historical and physical clues signaling dangerous, life-threatening conditions such as deep space neck infections. Peritonsillar abscess (PTA) is a well-known deep space neck infection and a serious complication of bacterial pharyngitis or tonsillitis. Occurring in approximately 30 per 100 000 individuals aged 5 to 59 years, peritonsillar infection can obstruct the upper airway or spread contiguously to surrounding structures in the neck. An understanding of age-specific disease prevalence, throat and neck anatomy, carefully chosen diagnostics, and procedural competency are all required to effectively manage pharyngitis, tonsillitis, and PTA.

A careful clinical examination can help differentiate pharyngitis, tonsillitis, and PTA. Using a tongue blade and having the patient yawn or say “ahh” will elevate the palate and uvula, providing
a better view of the oropharynx, palatine tonsils, and peritonsillar tissue. Pharyngitis clinically appears as erythematous and inflamed pharyngeal mucosa. Acute tonsillitis manifests as redness and swelling of the tonsils and tonsillar pillars. Tonsillar exudate may be present, and clinicians may palpate tender cervical lymph nodes. A PTA causes marked unilateral swelling of the peritonsillar soft tissue, deviation of the uvula away from the affected side, and palpable fluctuance. Patients may also present with trismus owing to spasm of the interior pterygoid muscle and with a muffled or “hot potato” voice owing to throat swelling. Unilateral otalgia caused by referred pain also suggests peritonsillar infection, phlegmon, or abscess. In severe cases, symptoms of upper airway obstruction such as respiratory distress, drooling, stridor, and tripod positioning may occur (Table 13.1). Bedside laryngoscopy, often performed by clinicians familiar with this technique, or in consultation with otolaryngology, can confirm anatomic findings of airway obstruction. These patients may rapidly decompensate and may need emergent intubation or tracheostomy in the operating room.

Although pharyngitis and tonsillitis are most often attributable to viral infection or β-hemolytic GAS, providers should consider a broad differential diagnosis for patients presenting with sore throat.

Commonly transmitted seasonal respiratory viruses, notably rhinovirus, adenovirus, coronaviruses and influenza virus, are the most common causes of viral pharyngitis. These do not require special testing and have a self-limited course. SARS-CoV-2, the virus that causes COVID-19, can also manifest as pharyngitis. Other viral agents include Epstein-Barr virus (EBV), human immunodeficiency virus (HIV), and herpes simplex virus (HSV). EBV causes infectious mononucleosis and is transmitted through oral contact, often in adolescence and young adulthood. Clinically, it appears as tonsillopharyngitis with tonsillar exudate and posterior cervical lymphadenopathy and is associated with high fever, malaise, and fatigue. Patients placed on penicillin-based antibiotics for treatment of presumed streptococcal infection may develop a rash when infected with EBV. Clinicians should examine for splenomegaly and take note of atypical lymphocytes on blood work to aid in the diagnosis of EBV. The acute phase of HIV infection occurs approximately 2 to 4 weeks post exposure and may present with fever, a nonexudative pharyngitis, and cervical adenopathy as part of a flulike syndrome. Physicians should consider this diagnosis in patients with high-risk behaviors or patients with coexisting sexually transmitted infections. The presence of oropharyngeal or tongue ulcers should prompt an evaluation for HSV pharyngitis.

β-Hemolytic GAS accounts for almost 25% of adult cases of tonsillopharyngitis. Other important but less common bacteria include Group C or Group G Streptococcus, Fusobacterium, Mycoplasma pneumonia, Neisseria gonorrhoeae, and Chlamydia pneumoniae. Fusobacterium is the causative
agent of a rare disease process, Lemierre syndrome, also known as septic thrombophlebitis of the internal jugular vein. Fusobacterium is an oropharyngeal anaerobe that colonizes young patients. Lemierre Syndrome presents as pharyngitis with tonsillar exudates, jaw pain, and possible swelling of the neck or angle of the jaw. Unvaccinated patients or those from developing countries are at risk for pharyngitis owing to Corynebacterium diphtheriae, which causes pharyngitis with a gray membrane that bleeds when prodded.

The differential diagnosis for PTA includes other causes of deep space neck infections and upper airway obstruction. Retropharyngeal abscess, common in early childhood, also causes high fever, throat pain, and trismus. It may also produce neck stiffness caused by torticollis, especially with attempted neck extension, and less prominent peritonsillar soft tissue swelling on examination of the throat. A parapharyngeal abscess can cause a toxic appearance and neck stiffness, as well as displacement of the pharyngeal wall or bulging of the posterior tonsillar pillar. Although less common in individuals vaccinated against Haemophilus influenzae B, upper airway obstruction resulting from acute epiglottitis is a diagnostic consideration in this patient population. Young children with epiglottitis attributable to Haemophilus influenzae B may present with symptoms of impending airway obstruction with tripod positioning, drooling, stridor, and tachypnea. Older children, adolescents, and adults with epiglottitis may exhibit severe sore throat, dysphagia, and drooling without signs of airway obstruction.