대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Pulmonary Alveolar Proteinosis with Tuberculosis

Radiologic Findings

Chest radiograph shows bilateral diffuse air-space consolidation, more prominent in the bases and a large amount of pleural effusion in the right hemithorax. HRCT scans show extensive air-space consolidation and ground glass attenuation. In addition, reticular pattern is apparent, presumably representing thickening of the interlobular septa, showing a typical crazy paving appearance. A more dense consolidation with air-bronchogram is noted in the right lower lobe.
Pulmonary alveolar proteinosis with Mycobacterium tuberculosis infection was confirmed by bronchoalveolar lavage (BAL) and sputum AFB stain.

Brief Review

Pulmonary alveolar proteinosis (PAP) is a disease characterized by filling of the alveolar spaces with a periodic acid-Shiff-positive proteinaceous material, rich in lipid (1). The pathogenesis of this disease is poorly understood, and the majority of cases are considered to be idiopathic. Some cases result from exposure to dusts (particularly silica) or from immunologic disturbances due to immunodeficiency, leukemia, lymphoma, or chemotherapy. PAP occurs four times as frequently in men as in women (2). Patients range in age from a few months to more than 70 years, with two-thirds of patients being between 30 and 50 years old.
The typical radiograph shows a bilateral patchy, diffuse, or perihilar ill-defined nodular or confluent airspace pattern, which is usually most severe in the lung bases. HRCT findings include bilateral areas of ground-glass opacity, smooth interlobular septal thickening in lung regions showing ground-glass opacity (i.e., crazy-paving), consolidation and a patchy or geographic distribution. The thickened interlobular septa were present within area of consolidation, and were shown on open-lung biopsy to reflect septal edema. Interstitial abnormalities characterized by the presence of alveolar wall infiltration by lymphocytes and macrophages, and interstitial edema. These findings probably reflect interstitial inflammation (3). Septal thickening can also represent interstitial accumulation of the proteinaceous material. It should be emphasized that in patients with alveolar proteinosis, septal thickening is usually visible only in regions of ground-glass opacity.
CT can demonstrate a focal pneumonia in patients who have PAP that is not apparent on plain radiograph. Superimposed infection, often by Nocardia asteroides is a common complication of alveolar proteinosis. By detecting focal areas of dense consolidation or abscess formation, CT may confirm a clinical suspicion of superimposed infection. In early studies, infection with Nocardia was reported in as many as 8% of patients who had alveolar proteinosis (4). In is now less common, presumably owing to the use of BAL in treatment of affected patients (1). More recently, some authors have noted an association of pulmonary alveolar proteinosis with Mycobacterium avium-intracellulare and Pneumocystis carinii infection (1).

References

1. Wang BM, Stern EJ, Schmidt RA, et al. Diagnosing pulmonary alveolar proteinosis: a review and an update. Chest 1997;111:460-466.
2. Webb WR, Muller NL, Naidich DP. High-resolution CT of the lung. 3rd ed. Philadephia: Lippincott-Raven press 2000; 390-393.
3. Miller PA, Ravin CE, walker Smith GJ, et al. Pulmonary alveolar proteinosis with interstitial involvement. AJR 1981; 137: 1069-1071.
4. Davidson JM, MacLeod WM. Pulmonary alveolar proteinosis. Br J Dis Chest 1969; 63:13-28.

Keywords

Lung, Metabolic and storage lung disesae, infection,