Isolated intrathoracic presentation of Mycobacterium avium complex in an immunocompetent child.

Mycobacterium avium complex (MAC) is a rare cause of isolated intrathoracic disease in the immunocompetent child; delays in diagnosis and treatment are common. The current case is an 11-month-old girl with symptoms, signs, and radiographic findings of bronchial obstruction. Comparison of this case to the literature revealed that there is a characteristic presentation of intrathoracic MAC infection in immunocompetent children (children aged 3 years or less, without exposure to Mycobacterium tuberculosis, presenting with clinical and radiographic evidence of bronchial obstruction) that should increase our index of suspicion for this diagnosis. This is particularly important since M. tuberculosis can present in a similar pattern.