Distinguishing Tonsillar Cyst from Peritonsillar Abscess
A peritonsillar abscess presents with acute severe symptoms including fever, severe throat pain, trismus, "hot potato" voice, and unilateral tonsillar bulging with uvular deviation, while a tonsillar cyst is typically asymptomatic or minimally symptomatic, discovered incidentally, and lacks inflammatory signs. 1, 2
Clinical Features of Peritonsillar Abscess
Cardinal Presenting Symptoms
- Fever (temperature ≥38.3°C) is a hallmark feature 1, 2
- Severe unilateral throat pain with odynophagia (painful swallowing) 1, 3
- Trismus (difficulty opening the mouth due to muscle spasm) 1, 2
- "Hot potato" voice (muffled speech quality) 1
- Dysphagia with drooling in severe cases 1, 3
Physical Examination Findings
- Unilateral peritonsillar swelling with medial displacement of the affected tonsil 3
- Uvular deviation away from the affected side 3
- Erythema and edema of the soft palate and tonsillar pillar 2
- Cervical lymphadenopathy (tender, enlarged nodes) 2
- Fluctuance may be palpable if abscess is well-formed 2
Systemic Signs
- Patients appear acutely ill with systemic toxicity 1
- Dehydration from inability to swallow 1
- Risk of airway compromise in severe cases 1
Clinical Features of Tonsillar Cyst
Typical Presentation
- Asymptomatic or minimally symptomatic in most cases
- Usually discovered incidentally during routine examination
- No fever or systemic signs of infection
- No trismus or difficulty opening mouth
- Normal voice quality without muffled speech
Physical Examination Findings
- Smooth, rounded swelling on tonsil surface
- No erythema or inflammatory changes
- No uvular deviation
- Bilateral tonsillar symmetry typically maintained
- Non-tender to palpation
- Translucent or yellowish appearance may be visible
Diagnostic Approach
When Clinical Examination is Sufficient
- Peritonsillar abscess can be diagnosed clinically in most cases based on the constellation of fever, trismus, unilateral swelling, and uvular deviation 1, 2
- Tonsillar cyst diagnosis is straightforward when the lesion is asymptomatic with no inflammatory features
When Imaging is Indicated
- Ultrasound can verify peritonsillar abscess presence in approximately 90% of cases when clinical examination is limited by trismus or poor cooperation 4
- CT scan with IV contrast is indicated when diagnosis is uncertain, bilateral involvement is suspected, or deep neck extension is a concern 3, 5
- Imaging helps distinguish phlegmonous peritonsillitis (cellulitis without abscess) from true abscess formation 4
Treatment Implications
Peritonsillar Abscess Management
- Immediate drainage (needle aspiration, incision and drainage, or immediate tonsillectomy) is required 1, 2, 5
- Antibiotic therapy effective against Group A streptococcus and oral anaerobes (penicillin, clindamycin, amoxicillin-clavulanate, or metronidazole) 6, 1, 2
- Supportive care including hydration and pain control 1
- Corticosteroids may reduce symptoms and speed recovery 5
- Interval tonsillectomy should be considered if history of >1 peritonsillar abscess 7, 6
Tonsillar Cyst Management
- Observation is appropriate for asymptomatic cysts
- No antibiotics are needed as there is no infection
- Surgical excision only if symptomatic or causing concern
Critical Pitfalls to Avoid
- Do not confuse phlegmonous peritonsillitis with abscess: The former presents with similar symptoms but lacks pus collection and requires only antibiotics, not drainage 4
- Do not miss bilateral peritonsillar abscess: Though rare, bilateral involvement can occur and may present with more symmetric findings, requiring high clinical suspicion and imaging 3
- Do not delay drainage of confirmed abscess: Complications include airway obstruction, aspiration, and extension into deep neck spaces 1
- Do not assume all unilateral tonsillar swelling is abscess: Tonsillar cysts, lymphoma, and other masses can mimic abscess but lack acute inflammatory features