We report an unusual case of cutaneous tuberculosis that developed at the exact site where a Mantoux test (also known as PPD test) was performed. A 25 year old male patient, recently diagnosed with HIV infection and acquired immunodeficiency syndrome (AIDS), in use of lamivudine, efavirenz and dolutegravir for two months, reported cough, night sweats and weight loss. Mantoux test was performed, ordered by his general practitioner, however, the patient presented an intense inflammatory response at the test site with subsequent ulcer formation within four weeks. It was first suspected that it corresponded to some type of exacerbated drug reaction to the antigens present in the test, tuberculid or that it was a case of tuberculous chancre, that is, an exogenous infection of the bacillus in a patient with a low immune response. A histopathological examination of a biopsy performed at the edge of the ulcer showed the presence of lymphocytic inflammatory infiltrate with granulomatous outlines and, although rare, alcohol-acid resistant bacilli. It could be inferred that the ulcer corresponded to a case of tuberculous chancre at the exact site of application of a diagnostic test for tuberculosis. The patient was also diagnosed with pulmonary tuberculosis, confirmed by real time PCR assay in sputum, which identified rifampicin-sensitive bacilli. The treatment was performed with pyrazinamide, rifampicin, isoniazid and ethambutol, with good response.

Tuberculosis is the infectious disease that kills the most in the world, reaching 1 million deaths per year. The cutaneous form is uncommon, since twenty per cent of the cases are extrapulmonary and, of these, only 1 to 3% affect the skin, with many forms of manifestation described. The Mantoux test (also known as PPD skin test) consists of the intradermal inoculation of a protein derivative of M. tuberculosis in order to assess the immune response to this antigen.
This study aims to report an unusual case of cutaneous tuberculosis that developed at the exact site where a Mantoux test was performed. A 25-year-old male patient, recently diagnosed with HIV infection and acquired immunodeficiency syndrome (AIDS), in use of lamivudine, efavirenz and dolutegravir for two months, reported cough, night sweats and weight loss. Mantoux test was performed, ordered by his general practitioner, however, the patient presented an intense inflammatory response at the test site with subsequent ulcer formation within four weeks.It was first suspected that it corresponded to some type of exacerbated drug reaction to the antigens present in the test, tuberculid or a case of tuberculous chancre, that is, an exogenous infection of the bacillus in a patient with a poor immune response. The histopathological examination of a biopsy performed at the edge of the ulcer showed the presence of lymphocytic inflammatory infiltrate with granulomatous outlines and alcohol-acid resistant bacilli. It could be inferred that the ulcer corresponded to a case of tuberculous chancre. The patient was also diagnosed with pulmonary tuberculosis, confirmed by real time PCR assay in sputum, which identified rifampicin-sensitive bacilli. The treatment was performed with pyrazinamide, rifampicin, isoniazid and ethambutol, with good response.
Despite being one of the oldest diseases on the planet, tuberculosis continues to be a serious health problem nowadays, especially in developing countries. Diagnosis is challenging since tuberculosis can mimic several diseases and it is not always possible to find the bacillus. A high index of suspicion is important so that dermatologists do not miss this important diagnosis.

ESDR167 - Unusual case of tuberculous chancre at the exact site of application of the Mantoux test

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