[A young case of pulmonary tuberculosis with atypical tumor shadow on chest computed tomography and its difficulty in diagnosis].

Background: Diagnosis of pulmonary tuberculosis is usually made by diagnostic imaging such as chest X-ray or computed tomography (CT), and sputum test including smear and polymerase chain reaction (PCR) test. However there is difficulty in making diagnose when atypical imaging and negative sputum test are presented, followed by diagnostic delay.

Case: A 26-year-old man from Philippines consulted other clinic because of dry cough and was pointed out mass shadow in right upper lung field in his chest CT. He visited our office because of positive interferon gamma release assay, but repeated sputum test could not find tuberculosis. Bleeding from mass lesion failed to perform biopsy by bronchoscope, and we failed to find tuberculosis by smear and PCR test from bronchial brushing and wash. Transthoracic needle biopsy from his mass lesion revealed multiple non-caseous granuloma, and lead to make a decision about starting medication. Four weeks later sputum culture from his first visit revealed positive, and diagnosis of tuberculosis was made.

Discussion: For avoiding therapy delay it is important to perform invasive diagnostic procedure including histological examination and clinical decision of starting medication, when conservative diagnostic procedure such as sputum test or diagnostic imaging present atypical finding for diagnosing tuberculosis.