peritonsillar abscess

**Definition:** A collection of pus in the peritonsillar space, which lies between the tonsillar capsule and the superior pharyngeal constrictor. It is also called quinsy.

**Pathophysiology:** - It usually follows acute tonsillitis or pharyngitis. It can also arise from infection of the Weber glands (minor salivary glands in the superior tonsillar pole). Early peritonsillar cellulitis can progress to abscess. - The infection is typically polymicrobial. The most common organisms are Group A Streptococcus (S. pyogenes), S. aureus (including MRSA), and oral anaerobes (Fusobacterium, Prevotella, Peptostreptococcus). - Risk factors include recurrent tonsillitis, smoking, and poor dental hygiene. Peak incidence is in adolescents and young adults (about 15–30 years).

**Clinical presentation:** - Severe unilateral sore throat with odynophagia, fever, and malaise - **"Hot potato" (muffled) voice** - **Trismus** (from irritation of the medial pterygoid muscle) - Drooling and pain referred to the ipsilateral ear (otalgia) - Tender cervical lymphadenopathy - On exam, the tonsil is displaced inferomedially and the soft palate is swollen and erythematous. **The uvula deviates toward the contralateral (unaffected) side.**

**Diagnosis:** - Diagnosis is mainly clinical. - Needle aspiration is both diagnostic and therapeutic, because purulent fluid confirms the abscess. - Contrast CT of the neck can help if the diagnosis is unclear or if you suspect extension into deeper neck spaces. Intraoral ultrasound is also an option. - Consider a monospot or heterophile test in young patients, since infectious mononucleosis can mimic the presentation.

**Management:** - **Drainage:** Needle aspiration or incision and drainage. - **Antibiotics:** Cover Group A Strep and oral anaerobes, for example ampicillin-sulbactam, or penicillin plus metronidazole. Clindamycin is an option for penicillin-allergic patients, and MRSA coverage is added if risk factors are present. - **Supportive care:** IV fluids, analgesia, and often corticosteroids. - **Tonsillectomy:** Consider interval tonsillectomy for recurrent abscess or recurrent tonsillitis. Immediate ("quinsy") tonsillectomy is rarely needed.

**Complications:** - Airway obstruction - Extension into the parapharyngeal or retropharyngeal space, leading to mediastinitis - Lemierre syndrome (septic thrombophlebitis of the internal jugular vein, classically from Fusobacterium necrophorum) - Carotid artery erosion - Aspiration pneumonia (from rupture)

**Differentials (high-yield for boards):** - **Peritonsillar cellulitis:** no fluctuance and no pus on aspiration. It responds to antibiotics alone. - **Retropharyngeal abscess:** typically occurs in young children. It causes neck stiffness and pain with swallowing, and lateral neck X-ray shows widened prevertebral soft tissue. - **Epiglottitis:** presents with a "thumbprint sign," stridor, and a tripod posture. - **Infectious mononucleosis:** causes exudative tonsillitis with posterior cervical lymphadenopathy. - **Ludwig angina:** a bilateral submandibular space infection with a swollen floor of the mouth.

**Board pearl:** A teenager with a severe unilateral sore throat, trismus, a muffled voice, and uvular deviation has a peritonsillar abscess. The next step is drainage (needle aspiration or I&D) plus antibiotics.