Extensive mediastinal lymphadenopathy in an adult immunocompetent woman caused by Mycobacterium avium complex.

We report a case of extensive mediastinal lymphadenopathy in a 29-year-old immunocompetent woman, which was thought to be caused by Mycobacterium tuberculosis (MTB). Chest radiographs showed deterioration while the patient was receiving antituberculous medication for 8 months. After isolation of Mycobacterium avium complex (MAC) from a lymph node aspiration biopsy and switch to a MAC-specific therapeutic regimen, the lesion almost completely disappeared within 1 year. To our knowledge, this is the first report of an extensive mediastinal lymphadenopathy caused by MAC in an immunocompetent adult.