A case of tuberculosis of the mandibular gingiva

Oral tuberculosis is rare. We report a case of a patient with oral tuberculosis in the lower gingiva. The patient was an 83-year-old woman with no previous history of tuberculosis. Her chief complaint was a refractory ulcer of the mandibular gingiva expanding over a period of 11 months. The surface of the ulcer was granular, without induration, and part of the mandibular bone was exposed. CT showed a slightly enhanced area coinciding with the ulcer. T-spot blood test was positive. Tuberculosis was suspected, and she was referred to the Department of Infectious Diseases. Chest CT did not indicate pulmonary tuberculosis, but an acidophilic bacterium test returned positive for both Ziehl-Neelsen staining by direct smear examination and culture inspection. In addition, Mycobacterium tuberculosis was identified through PCR. She was diagnosed with tuberculosis, and treatment using rifampicin, isoniazid, and ethambutol was started. A gingival biopsy was performed after sputum examinations returned negative three times. Pathologically, the granuloma was composed of caseous necrosis surrounded by Langhans giant cells, epithelioid cells and infiltration of lymphocytes, which lead to a final diagnosis of oral tuberculosis. The ulcer healed after two months of chemotherapy. Medication was continued for one year, and there was no recurrence.