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EN4.38 | Acute and Chronic Tonsillitis — SDL Guide (Part 2)

Diagnosis and Differential Diagnosis

The differential diagnosis of acute tonsillitis includes several conditions that can mimic it closely but require very different management. Failure to distinguish these conditions is among the most clinically dangerous errors in ENT outpatient practice. The key diagnostic distinctions are based on the appearance of the exudate, the pattern of lymphadenopathy, associated systemic features, and specific investigations.

GABHS (streptococcal) tonsillitis: bilateral tonsillar erythema and follicular or punctate white exudate; tender anterior cervical lymphadenopathy; high fever; absence of cough (a Centor criterion); no significant splenomegaly. Throat swab grows Group A beta-haemolytic Streptococcus. Responds to penicillin.

Viral tonsillitis: usually milder; bilateral erythema with or without exudate; prominent upper respiratory tract symptoms (cough, coryza, conjunctivitis); lower or absent fever; does not respond to antibiotics.

Glandular fever (infectious mononucleosis, EBV): typically in adolescents; severe illness disproportionate to the tonsillar findings; membranous exudate covering both tonsils; markedly enlarged posterior cervical lymph nodes (not just anterior chain); splenomegaly (present in ~50% — risk of splenic rupture with contact sport); hepatitis (elevated LFTs); atypical lymphocytes on blood film; monospot test positive. DO NOT prescribe amoxicillin — causes a maculopapular rash in ~80–100% of EBV patients.

Diphtheria (Corynebacterium diphtheriae): now rare in immunised populations but must be remembered. The membrane is grey-white, thick, adherent, extends beyond the tonsillar pillars onto the pharyngeal wall and soft palate, and bleeds when attempts are made to remove it (unlike the white follicular exudate of streptococcal tonsillitis, which wipes off easily). Associated with bull-neck lymphadenopathy and systemic toxaemia. Diphtheria toxin causes myocarditis and cranial nerve palsies.

Vincent's angina (acute necrotising ulcerative tonsillitis): caused by synergistic infection with Fusobacterium necrophorum and Treponema vincenti (Vincent's organisms); unilateral grey-green membranous ulceration of the tonsil with a characteristic putrid smell; painful but minimal fever; responds to penicillin + metronidazole.

Complications of acute tonsillitis:

Local (suppurative):
- Peritonsillar abscess (quinsy): pus forms in the peritonsillar space (between the tonsillar capsule and the superior constrictor), most often in the anterosuperior quadrant. Key signs: unilateral swelling, uvula displaced to the contralateral side, trismus, 'hot-potato' voice, drooling. Management: needle aspiration (first-line, office-based) or incision and drainage (I&D) under local anaesthesia; interval tonsillectomy after the acute episode has resolved.
- Parapharyngeal abscess: extension of infection beyond the superior constrictor into the parapharyngeal space; presents with trismus, neck swelling, and systemic toxaemia. Requires CT neck, IV antibiotics, and surgical drainage.
- Retropharyngeal abscess: more common in children; presents with dysphagia, neck stiffness, stridor, and a bulging of the posterior pharyngeal wall. Requires CT and urgent surgical drainage.

Regional:
- Acute otitis media (spread via Eustachian tube)
- Acute sinusitis (contiguous lymphatic spread)

Systemic (non-suppurative, post-GABHS):
- Acute rheumatic fever (ARF): autoimmune cross-reaction between GABHS M protein and cardiac valvular epitopes → pancarditis, migratory polyarthritis, Sydenham's chorea. Prevention requires completing the full 10-day penicillin course.
- Post-streptococcal glomerulonephritis (PSGN): immune complex deposition in the glomeruli after specific nephritogenic strains of GABHS; presents 1–3 weeks after throat infection with haematuria, proteinuria, and hypertension.

Management of Acute and Chronic Tonsillitis

Management of tonsillitis follows a stepwise approach — conservative for uncomplicated acute episodes, more aggressive when complications arise, and surgical when the pattern of recurrence meets established criteria. The cornerstone of medical management is an adequate antibiotic course where indicated, combined with supportive measures. The cornerstone of surgical management is the decision to operate based on validated criteria rather than on parental or patient pressure alone. Understanding this distinction prevents both under-treatment (failure to drain an abscess, failure to complete the antibiotic course) and over-treatment (unnecessary tonsillectomy before criteria are met, prescribing amoxicillin without ruling out EBV). The management framework below follows this three-tier structure: medical management of acute episodes first, management of complications second, and surgical management last — with criteria-based decision-making at each step.

1. Medical management of acute tonsillitis:
- Analgesia and antipyretics: regular paracetamol ± ibuprofen; adequate oral fluids; a short course of soluble paracetamol or NSAID spray may ease swallowing.
- Antibiotics (for suspected GABHS — Centor score ≥3 or positive throat swab):
- First-line: Phenoxymethylpenicillin (Penicillin V) 500 mg four times daily for 10 days (full course is mandatory to eradicate GABHS and prevent rheumatic fever).
- Penicillin allergy: erythromycin or azithromycin.
- Do NOT prescribe amoxicillin if EBV (glandular fever) is suspected — causes characteristic maculopapular rash in ~80–100% of EBV patients.
- DO NOT use aminopenicillins (amoxicillin/ampicillin) empirically for tonsillitis without ruling out EBV.
- Hospitalisation for severe illness: inability to swallow fluids (IV hydration needed), threatened airway, young children, immunocompromised patients.

2. Management of peritonsillar abscess (quinsy):
- Needle aspiration: the first-line intervention. A wide-bore needle (18-gauge) is inserted into the soft palate at the point of maximal fluctuance (anterosuperior quadrant), pus is aspirated, and a sample is sent for culture. Provides immediate relief of trismus and dysphagia. Repeat if reaccumulation occurs.
- Incision and drainage (I&D): if needle aspiration fails or is not feasible; a small incision is made at the point of maximal fluctuance under local anaesthesia and the cavity drained.
- Intravenous antibiotics: penicillin + metronidazole (for anaerobic coverage) while pus is draining.
- Interval tonsillectomy: performed 6–8 weeks after the acute episode has completely resolved; indicated for a first episode of quinsy in most patients to prevent recurrence.

3. Indications for tonsillectomy — the Paradise criteria:
Tonsillectomy is indicated when the frequency and severity of recurrent tonsillitis is sufficient to impair quality of life and justify the surgical risk. The Paradise criteria are the accepted standard:

Frequency threshold	Period
≥7 documented episodes	in the preceding 1 year
≥5 documented episodes per year	for 2 consecutive years
≥3 documented episodes per year	for 3 consecutive years

Each episode must be documented and include sore throat PLUS at least one of: temperature >38.3°C, cervical lymphadenopathy, tonsillar exudate, or positive throat swab for GABHS.

Additional indications for tonsillectomy include: peritonsillar abscess (particularly recurrent), obstructive sleep apnoea / sleep-disordered breathing due to tonsillar hypertrophy (grades 3–4), and suspicion of tonsillar malignancy (unilateral tonsillar enlargement in an adult must be biopsied to exclude lymphoma or squamous cell carcinoma).

4. Tonsillectomy — procedure and complications:
Performed under general anaesthesia via the oral route. The tonsil is dissected free from its bed within the fibrous capsule. The tonsillar arteries are ligated or diathermied. Major complications:
- Primary haemorrhage: within 24 hours of surgery — return to theatre.
- Reactionary haemorrhage: within the first 24 hours, usually when blood pressure normalises.
- Secondary haemorrhage: 5–10 days post-operatively — from sloughing of the tonsillar fossa eschar. The most common and clinically important complication in the post-discharge period. Patients should be warned and instructed to return immediately if bleeding occurs.
- Rare: velopharyngeal insufficiency, nasopharyngeal stenosis.

Self-Assessment: Tonsillitis

Use the following questions to consolidate your learning from this module. Each question targets a key competency in EN4.38 — structured clinical reasoning about tonsillitis history, complications, and management. Answer before reading the explanation.

Question 1. A 15-year-old presents with a 7-day sore throat, bilateral tonsillar exudate, posterior cervical lymphadenopathy, splenomegaly, and a monospot test positive. The doctor prescribes amoxicillin. (a) What is the likely diagnosis? (b) What will happen after the amoxicillin is given? (c) What is the correct management?

Answer: (a) Infectious mononucleosis (glandular fever) due to EBV — the triad of tonsillopharyngitis + posterior cervical lymphadenopathy + splenomegaly with a positive monospot test is diagnostic. (b) Within 2–3 days of amoxicillin administration, approximately 80–100% of patients with EBV will develop a widespread maculopapular skin rash — an immune-mediated reaction to the amoxicillin–EBV combination (not a true penicillin allergy). (c) Correct management is supportive: rest, adequate fluids, analgesia (paracetamol/NSAIDs). Avoid contact sports until splenomegaly has resolved (risk of splenic rupture). No antibiotics unless bacterial superinfection is confirmed.

Question 2. A middle-aged woman has had 5 documented episodes of tonsillitis this year and 5 per year for the previous year, each with fever and tonsillar exudate. Does she meet the Paradise criteria for tonsillectomy? What complications of acute tonsillitis should the patient have been counselled about at each episode?

Answer: Yes — she meets the Paradise criterion of ≥5 documented episodes per year for 2 consecutive years. Complications of acute tonsillitis to counsel about: local — peritonsillar abscess (quinsy), parapharyngeal abscess, retropharyngeal abscess; systemic — acute rheumatic fever and post-streptococcal glomerulonephritis if GABHS is the causative organism and antibiotic course is not completed. She should have been emphasised the importance of completing the full 10-day penicillin course.

Question 3. What are the four Centor criteria? What score would suggest that empirical antibiotics are appropriate and a throat swab is strongly indicated?

Answer: The four Centor criteria are: (1) tonsillar exudate, (2) tender anterior cervical lymphadenopathy, (3) fever >38°C, (4) absence of cough. A Centor score of 3 or 4 suggests moderate to high probability of GABHS tonsillitis — a throat swab is strongly indicated and empirical antibiotics are appropriate (Penicillin V 500 mg four times daily for 10 days). Score 0–1: antibiotic therapy is not recommended as bacterial tonsillitis is unlikely.