RESUMEN
A previously healthy man developed pulmonary symptoms 2 weeks after starting treatment with a tumour necrosis factor (TNF) inhibitor. A negative interferon-gamma release assay (IGRA) test was obtained prior to TNF inhibitor exposure, without consideration of the fact that the patient was already immunosuppressed and had a previous positive IGRA test 17 months earlier. The patient was treated for pneumonia twice but did not achieve remission. His physical health progressively deteriorated over the following months. Malignancy was suspected but not found. Eight months after the onset of symptoms, Mycobacterium tuberculosis was found in samples from mediastinal lymph nodes, and the patient was diagnosed with multidrug-resistant tuberculosis (MDR-TB).This case illustrates the diagnostic challenge of TB, the need to raise awareness of the increased risk of TB in patients treated with TNF inhibitors and the need to increase knowledge regarding the effect of immunosuppressive agents on IGRA tests.