Tonsillitis

The palatine tonsils are lymphoid tissue at the entrance to the pharynx, positioned to sample inhaled and ingested antigen. Their deep crypts give a large surface area for that purpose — and also trap debris and organisms, which is why they are prone to infection and why chronic disease tends to recur.

Viral infection accounts for the majority of cases, in the region of 70–85% in adults. Rhinovirus, adenovirus, coronavirus, influenza, parainfluenza and Epstein-Barr virus are the usual agents. Viral tonsillitis typically comes with the rest of an upper respiratory illness — cough, coryza, hoarseness and conjunctivitis — and those features are themselves diagnostically useful, because they argue against bacterial infection.

Bacterial tonsillitis is most often caused by group A beta-haemolytic Streptococcus pyogenes, responsible for perhaps 15–30% of cases in children and 5–15% in adults. Less common bacterial causes include group C and G streptococci, Fusobacterium necrophorum — important because it causes Lemierre’s syndrome — and, rarely now, Corynebacterium diphtheriae.

Transmission is by respiratory droplet and direct contact, with an incubation period of two to five days for streptococcal infection. Spread is favoured by crowding, which is why schools and households see clusters. Peak incidence is between 5 and 15 years of age.

The reason the distinction between viral and bacterial matters is not the acute illness — most streptococcal sore throats resolve without treatment in about a week — but the non-suppurative complications: acute rheumatic fever and post-streptococcal glomerulonephritis.

Sore throat, odynophagia and fever are the core features. The tonsils are enlarged and erythematous, often with white or yellow exudate in the crypts, and the tonsillar lymph nodes are enlarged and tender.

Referred otalgia is common, since the tonsil and the ear share glossopharyngeal innervation, and can be the dominant complaint. Halitosis, a muffled or “hot potato” voice, headache, malaise and anorexia are usual. Children may present with abdominal pain and vomiting rather than throat symptoms, and febrile convulsion is possible.

The Centor criteria — tonsillar exudate, tender anterior cervical lymphadenopathy, fever above 38°C, and absence of cough — estimate the probability of streptococcal infection, with a point added for age 3–14 and subtracted for age over 44 in the modified score. They are a guide to testing and treatment, not a diagnosis.

Scarlet fever, with a sandpaper rash, strawberry tongue and circumoral pallor, indicates streptococcal infection. A rash following amoxicillin strongly suggests infectious mononucleosis rather than drug allergy.

Peritonsillar abscess (quinsy) is the commonest suppurative complication: severe unilateral pain, trismus, uvular deviation away from the swelling, drooling and a muffled voice. It requires drainage. Parapharyngeal and retropharyngeal abscess are deeper and more dangerous. Lemierre’s syndrome — septic thrombophlebitis of the internal jugular vein with septic emboli, usually from Fusobacterium — is rare and life-threatening, and should be considered when a young adult deteriorates after a sore throat.

Acute rheumatic fever follows untreated streptococcal infection by two to four weeks and can cause permanent valvular damage; post-streptococcal glomerulonephritis follows by one to three weeks. Obstructive sleep apnoea from chronic tonsillar hypertrophy is a separate and common problem in children.

Diagnosis is clinical, with testing used to identify streptococcal infection where treatment would change.

Rapid antigen detection testing is specific but less sensitive, so a negative test in a child with a high Centor score is usually confirmed by throat culture. Culture remains the reference standard but takes 24–48 hours. Neither test distinguishes infection from carriage, which is common in children and a frequent source of over-treatment.

Where mononucleosis is suspected — marked fatigue, posterior cervical or generalized lymphadenopathy, splenomegaly, a teenager or young adult — a full blood count showing atypical lymphocytes and a heterophile antibody (Monospot) test are indicated. Confirming it matters practically: it changes advice about contact sport because of splenic rupture risk, and it explains the amoxicillin rash.

Unilateral tonsillar enlargement persisting without infection, especially with weight loss or night sweats, requires ENT referral to exclude lymphoma or carcinoma.

Recurrent tonsillitis has a significant impact on school and work attendance, and tonsillectomy is considered where episodes are frequent and documented. Chronic tonsillar hypertrophy in children causes obstructive sleep apnoea, with downstream effects on growth, behaviour and school performance that are often not connected to the throat by the family. Tonsilloliths — calcified crypt debris — cause persistent halitosis and a foreign body sensation without active infection. Recurrent streptococcal infection in a child should prompt consideration of PANDAS where there is abrupt-onset obsessive-compulsive or tic symptomatology, though the entity remains contested.