Exogenous lipoid pneumonia: HRCT, MR, and pathologic findings

The objective of this study was to describe high-resolution CT (HRCT) and M R findings of exogenous Lipoid pneumonia and to correlate them with patholo gic findings. A retrospective review of the medical records of our institut ion revealed seven patients with a diagnosis of lipoid pneumonia based on c linical data, chest films, bronchoalveolar lavage, and follow-up. Both HRCT and MR imaging were reviewed by two readers. Pathologic examination of the resected specimen or surgical biopsies were also reviewed in the four avai lable cases. The HRCT findings were pulmonary consolidations (n = 6) with f atty (n = 3) or unspecific but low attenuation values (n = 3), areas of gro und-glass opacities (n = 5), septal lines, and centrilobular interstitial t hickening (n = 5). In five of the seven cases, a crazy-paving pattern of va rious spread was also present, either isolated (n = 1) or surrounding a pul monary consolidation. In two cases traction bronchiectasis and cystic chang es consistent with fibrosis were seen. At MR imaging (n = 2) a pulmonary co nsolidation of high signal intensity on T1-weighted image consistent with l ipid content was present in one case. Pathologic examination (n = 4) showed the coexistence of lobules with lesions of various ages, sometimes in cont iguous lobules, within the same patient. Recent lesions were those with alv eolar fill-in by spumous macrophages and almost normal alveolar walls and s eptae. In more advanced lesions, lobules were filled in with larger vacuole s often surrounded by inflammatory infiltrates of alveolar walls, bronchiol ar walls, and septa. The oldest lesions were characterized by fibrosis and parenchymal distortion around large lipid-containing vacuoles. The HRCT fin dings reflect pathologic findings in exogenous lipoid pneumonia. Al;though non-specific, consolidation areas of low attenuation values and crazy-pavin g pattern are frequently associated in exogenous lipoid pneumonia and are i ndicative of the diagnosis.