•Oral tuberculosis should be included in the differential diagnosis of oral lesions, irrespective of the existence of pulmonary signs and symptoms.•The diagnosis of oral tuberculosis is difficult and can be performed by pathological examination and PCR assays. A 45-year-old man presented with a 6-month history of a persistent painless ulcer on the tip of the tongue, with a slightly elevated margin. The lesion worsened to compromise the distal third of the tongue (Figure 1A). The patient did not smoke or drink alcohol. He had a history of HIV infection, with non-adherence to antiretroviral therapy (HIV1 RNA viral load of 31189/ml copies and CD4 + T-cell count of 200 cells/mm3). An incisional biopsy of the indurated upper border in the apex showed central necrotic tissue and chronically inflamed granulation with epithelioid cells (Figure 1B). Acid-fast bacilli were not identified on Ziehl–Neelsen staining. IS6110 real-time PCR for the detection of Mycobacterium tuberculosis complex in DNA extracted from formalin-fixed paraffin-embedded sections was positive. An anti-tuberculosis (TB) drug regimen consisting of isoniazid, rifampicin, pyrazinamide, and ethambutol was prescribed, with an adequate clinical response (Figure 1C). Oral TB is a rare entity accounting for only 0.1–1.5% of extrapulmonary TB cases.1Nemes R.M. Ianosi E.S. Pop C.S. Postolache P. Streba C.T. Olteanu M. et al.Tuberculosis of the oral cavity.Rom J Morphol Embryol. 2015; 56: 521-525PubMed Google Scholar It may represent primary disease, which is rare and occurs as a result of the direct inoculation of oral tissues, or may be secondary, due to hematogenous or lymphatic dissemination and extension to nearby structures. This case was considered post-primary TB since it is the most common presentation.2Kakisi O.K. Kechagia A.S. Kakisis I.K. Rafailidis P.I. Falagas M.E. Tuberculosis of the oral cavity: a systematic review.Eur J Oral Sci. 2010; 118: 103-109Crossref PubMed Scopus (69) Google Scholar Oral TB presents as ulcers, nodules, tuberculomas, fissures, or peri-apical granulomas. It may occur in any location on the oral mucosa, but the tongue is most commonly affected.2Kakisi O.K. Kechagia A.S. Kakisis I.K. Rafailidis P.I. Falagas M.E. Tuberculosis of the oral cavity: a systematic review.Eur J Oral Sci. 2010; 118: 103-109Crossref PubMed Scopus (69) Google Scholar The differential diagnosis includes traumatic or aphthous ulcers, actinomycosis, syphilitic ulcer, mycotic infections, Wegener's granuloma, sarcoidosis, Crohn's disease, and malignancy.3Gharebaghi N. Monsouri S.A. Darazam I.A. Mansouri D. Sajadi M.M. Mansouri N. A 40-year-old man with tongue lesions. Lingual and pulmonary tuberculosis (TB).Clin Infect Dis. 2011; 52 (1231, 1276–7)PubMed Google Scholar Ethics statement: Written informed consent was obtained from the patient for the publication of this case report. Conflict of interest: None of the authors report a conflict of interest, and there were no funding sources. All of the authors have submitted the ICMJE form for the disclosure of potential conflicts of interest.