An 88 year old Caucasian woman presents to the ER with hemoptysis. CT scan reveals bronchiectasis in the medial segment of the right middle lobe with scattered peripheral nodules. Findings are typical for Mycobacterium avium intracellulare complex (MAIC). This is an atypical mycobacterial infection seen in elderly females. It is thought that the imaging findings may be due to chronic suppression of a cough leading to retained secretions in the dependent portions of the ventral lung fields.
Rossi SE, Franquet T, Volpacchio M, et al. Tree-in-bud pattern at thin-section CT of the lungs: radiologic-pathologic overview. Radiographics 2005;25:789-801.