Sir, we read with interest the paper Primary tuberculosis masquerading as gingival enlargement (BDJ 2010; 208: 343–345).

Tuberculosis has a very high incidence in developing countries. According to WHO estimates 9.27 million new cases of tuberculosis (TB) occurred in 2007 with around 55% of global cases arising in Asia (South East Asia and Western Pacific regions), which is attributed to poor hygiene conditions.1

The authors of the paper presented a case of primary tuberculosis of the gingiva. Such a condition is considered a rare entity affecting approximately 0.05-5.00% of patients with TB2 as the oral cavity is considered to be immune due to local immunity of the mucous membrane.3 However, an increasing incidence of TB (due to Aids and emerging multi-drug resistant strains) means that we are likely to see many cases of tuberculosis in the oral cavity in future, so that TB should be considered as a differential diagnosis. The most usual presentation is as an ulcer on the tongue, gingival or buccal mucosa and as a radiolucency when bone is affected. Since the ulcers usually mimic squamous cell carcinoma, a diagnosis becomes more challenging.4 Mechanical tears and trauma in the oral cavity are considered one of the aetiological factors for inoculation of bacteria in the oral tissue from sputum. But surprisingly, there are very few cases of secondary tuberculosis in spite of a high incidence of sputum positive cases.

The authors have found positive sputum in their case. Acid fast bacilli can be found in saliva in a case of primary tuberculosis of the oral cavity but not in sputum. Positive sputum points to TB of pulmonary origin although sometimes, TB of the bronchioles is not evident on radiographs. To rule out that possibility, bronchoscopy or CT scan is mandatory. We therefore believe that the presented case is of secondary tuberculosis of the oral cavity.