TB of the oral cavity is uncommon and tonsillar lesions are extremely rare. Oral cavity TB may be either primary or secondary. Tongue and palate are the common sites whereas tonsillar TB is rare.4
The upper respiratory tract is generally resistant to TB. Saliva by virtue of its cleansing action is thought to have an inhibitory effect on tubercular bacilli. The presence of saprophytes, the antagonism of striated musculature to bacterial invasion, and thickness of the protective epithelial covering of the oropharyngeal mucosa have an inhibitory affect.5
Isolated pharyngeal lesions are acquired by inhalation with harbouring of disease in Waldayer’s ring. Extrapulmonary localisation of TB is rare, and is usually encountered in patients with poor host reaction due to chronic alcoholism, HIV infection, etc.6
In our case, the patient was seronegative for HIV infection and had no predisposing factors. Our patient had recurrent episodes of chronic tonsillitis which makes the epithelium vulnerable for other infections. Since he was an x-ray technician in a dental department, occupational exposure of the already inflamed tonsil to TB is the only possible explanation for the localisation of tubercular bacilli in Waldayer’s ring.
During our investigation we encountered normal ESR, negative sputum and throat swab culture, and normal chest x-ray. For confirmation, histological examination, acid fast staining and culture should be done. Culture of microorganisms has shown good results, although it has technical difficulties, lacks sensitivity, and may take 4–6 weeks. Sophisticated techniques such as PCR can be used alternatively, especially when the conventional methods of diagnosis renders equivocal results.3
In our patient the tissue PCR was also negative. If PCR shows negative results when TB is strongly suspected, PCR results should be correlated with histopathology before starting treatment.7
The most common local symptom of tonsillar TB is difficulty in swallowing, which was also seen in our case. The histological findings of the resected tonsils confirmed the diagnosis of tonsillar TB.5
Though the PCR was negative, on the basis of histopathology the antitubercular therapy was started for 6 months and the patient’s symptoms completely resolved. Nevertheless, a history of exposure must be elicited in order to establish a proper diagnosis. Chronic non-specific tonsillitis not responding to antibiotic treatment is a very important differential diagnosis which mimics tubercular tonsillitis and is commonly overlooked.
- Although TB of the tonsils is a relatively rare entity, a case with recurrent throat infection not responding to antibiotics, with evidence of inflamed tonsils, should alert the clinician to the possibility of TB as a causative factor, especially in regions where the incidence of TB is high.