RESUMEN
A 38-year-old man was admitted to our hospital with fever and skin rash, and he was diagnosed as having dermatomyositis. He was treated with anti-inflammatory steroid and immunosuppressive agents. On hospital day 48, chest computed tomography (CT) revealed a nodule measuring approximately 2 cm in size in the lower lobe of the right lung (S9). Bacterial and/or fungal infection was suspected, but there was no response to antibiotic or antifungal treatment. A week later, repeat chest CT revealed the tumor now measuring approximately 6 cm in size in the lower lobe of the right lung. We performed bronchoscopy, and bacteriological examination of the transbronchial biopsy specimen revealed pulmonary tuberculosis. Interferongamma release assay (IGRA) before the initiation of immunosuppressive treatment was negative, so we did not administer treatment for latent tuberculosis infection. He was, however, treated with isoniazid, rifampicin, ethambutol, and pyrazinamide for 9 months, following which radiological features improved gradually. Here we describe in detail this rare case of a negative IGRA result before immunosuppressive therapy in a relatively young Japanese man who went on to develop active tuberculosis with a rapidly-growing pulmonary lesion during hospitalization.