CTICasesMycobacterium Avium Complex (MAC) Infection Misidentified as Silicosis
Imaging findings
Chest radiograph shows hyperinflation and irregular lung opacities without convincing nodular disease. CT demonstrates tree-in-bud pattern with bronchiectasis predominantly in the middle lobe, lingula, and lower lobes, consistent with MAC infection. There are no calcified nodules or small rounded profusion of silicosis. The pattern is classic Lady Windermere syndrome-type MAC infection: middle lobe and lingula bronchiectasis with tree-in-bud nodules in an older white female.
Key takeaways
MAC infection classically presents in older thin white women with scoliosis, pectus excavatum, and mitral valve prolapse (Lady Windermere syndrome), producing middle lobe and lingula bronchiectasis with tree-in-bud nodules. It does not produce the rounded nodular profusion, PMF, or eggshell calcification of silicosis. In this case a patient was convinced her lung disease was caused by inhaling dust during home tile removal (silicosis), but cultures grew mycobacteria confirming MAC. The case illustrates the importance of culture results and proper correlation of CT findings with clinical and occupational exposure history.
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