Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Chronic hypersensitivity pneumonitis (extrinsic allergic alveolitis)
- Radiologic Findings
- (a) Chest radiograph shows ill-defined consolidation and diffuse reticulonodular opacities in the lung.
(b) Lung window of HRCT shows diffuse ground glass opacity, peribronchial, subfissural and peripheral consolidation, irregular and linear opacities with mild parenchymal distortion.
Follow up HRCT after 1 month show newly developed ground glass opacities in both lungs with partial resolving of previous consolidation.
- Brief Review
- Extrinsic allergic alveolitis (EAA) is a disorder in which repeated inhalation of particulate organic antigens causes a predominantly immunologic response in the air-exchange units of the lung.
The diagnosis of EAA is usually based on the characteristic clinical symptoms and signs, together with evidence of exposure and improvement following withdrawal.
Three stages:
1. In the acute stage the chest radiography is occasionally normal.
2. The most common radiographic finding in the acute or subacute stage is small pulmonary nodules, usually 1 to 3 mm. They are almost always bilateral. In the subacute phase the majority of patients have diffuse ground glass opacity and small nodulation on HRCT.
3. The characteristic radiologic changes in the chronic stage are of a scarring process with loss of lung volume, which has a marked (85%) upper lobe predominance. Chronic HRCT changes consist of coarse, irregular, linear opacities with parenchymal distortion.
- References
- 1. Silver SF, Muller NL, Miller RR, et al. Hypersensitivity pneumonitis: evaluation with CT. Radiology 1989;173:441-445
2. Peter Armstrong. Imaging of diseases of the chest 2nd ed. 541-546.
- Keywords
- Lung, Inhalation and aspiration disease, HP,