Pulmonary Alveolar Proteinosis

Fig. 20.7 Pulmonary alveolar proteinosis in a 52-year-old man. (a) Lung window image of CT scan (1.5-mm section thickness) obtained at level of azygos arch shows diffuse ground-glass opacity containing internal reticulation (crazy-paving appearance, arrows) in both lungs. Subpleural sparing is seen. (b) Coronal reformatted image (2.0-mm

section thickness) also demonstrates crazy-paving appearance (arrows) in both lungs. (c) High-magniÞcation (×200) photomicrograph of surgical biopsy specimen obtained from right lower lobe discloses Þlling of alveolar airspaces with Þnely granular eosinophilic material. Also note normal alveolar walls

Chronic lipoid pneumonia most commonly results in a focal, mass-like area of consolidation [15, 16].

sometimes fatal, cases can occur, but the disease is usually indolent.

CT–Pathology Comparisons

The crazy-paving pattern reßects intra-alveolar and interstitial accumulation of lipid-laden macrophages and hyperplasia of type II pneumocytes in the alveolar lining [17].

Patient Prognosis

The key in the management is identiÞcation and discontinuation of the exposure to the offending agent. Treatment is primarily supportive and generally conservative. Acute,

Pulmonary Alveolar Proteinosis

Pathology and Pathogenesis

Pulmonary alveolar proteinosis (PAP) is characterized by an intra-alveolar accumulation of lipid-rich eosinophilic material (Fig. 20.7). In primary PAP, it occurs as a result of impaired clearance of surfactant by alveolar macrophages due to the effects of an autoantibody directed against granulocyte-macrophage colony-stimulating factor (GM-CSF). The gross lung shows Þrm yellow-white nodules, some as large as 2 cm in diameter. Microscopically,

Fig. 20.8 Lipoid pneumonia (squalene aspiration pneumonia) in a 73-year-old man. (a, b) Lung window images of CT scans (2.5-mm section thickness) obtained at levels of right middle lobar bronchus (a) and liver dome (b), respectively, show patchy and extensive areas of ground-glass opacity harboring internal reticulation (crazy-paving appearance, arrows) in both lungs. (c) Low-magniÞcation (×10) photo-

micrograph of surgical biopsy specimen obtained from right lower lobe demonstrates consolidative lesions Þlled with inßammatory cells as well as areas (arrows) of interstitial thickening with loose Þbrosis and inßammation. (d) High-magniÞcation (×100) photomicrograph discloses alveolar Þlling with lipid-laden macrophages, other inßammatory cells, and Þbrin. Inset: lipid-laden macrophages (arrows)

pink granular material Þlls the air spaces, sometimes with a rim of retraction that separates the alveolar wall slightly from the exudates. Closer inspection of this material shows embedded clumps of dense globular material and cholesterol clefts [18].

Symptoms and Signs

Most patients with PAP present with progressive exertional dyspnea of insidious onset and cough [19]. Less commonly, fever, chest pain, or hemoptysis also occurs, especially if secondary infection is present. Almost one-third of patients are asymptomatic. The Þndings on physical examination can

be unremarkable, but there are inspiratory crackles in 50 % of patients and cyanosis in 25 %.

CT Findings

The characteristic TSCT Þnding is areas of GGO. The areas of GGO often have sharply deÞned margins, giving them a geographic appearance (Fig. 20.7). In most cases, intralobular interstitial and interlobular septal thickening can be seen, superimposed on the areas of GGO, forming the Òcrazypaving appearanceÓ [20, 21] (Fig. 20.7). The distribution of disease is variable: most commonly, it is random. Sometimes, areas of airspace consolidation may be present.