Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Subacute hypersensitivity pneumonitis
- Radiologic Findings
- Chest radiograph shows diffuse ill-defined nodules in both lungs.
High resolution CT demonstrates diffuse innumerable centrilobular nodules in both lungs.
Note that nodules spare the fissures and pleural surfaces.
A VATS biopsy was performed and pathologic specimens revealed the areas of interstitial inflammation and ill-defined granulomas, findings consistent with hypersensitivity pneumonitis (HP).
She is an ordinary housewife and her favorite pastime was a ceramic sculpture. Her symptoms and radiologic findings have gradually improved after initiation of corticosteroid therapy and after cessation of a ceramic sculpture.
- Brief Review
- Hypersensitivity pneumonitis (HP) is a diffuse granulomatous interstitial lung disease caused by inhalation of various antigenic organic particles. A high index of suspicion and meticulous acquisition of an environmental and occupational history are essential in making the diagnosis.
Lung biopsy is often necessary for confident diagnosis, and most cases of HP, whether acute or insidious, include the following four histologic features in variable amounts and combinations: cellular bronchiolitis, diffuse chronic interstitial inflammatory infiltrates (primarily consisting of lymphocytes and plasma cells), and poorly circumscribed interstitial nonnecrotizing (noncaseating) granulomas.
HP traditionally has been classified as manifesting in three phases: acute, subacute, and chronic.
Although this classification is helpful, patients often present with both subacute and chronic findings. Subacute HP is caused by intermittent or continuous exposure to low doses of antigen.
The characteristic high-resolution CT manifestations of subacute HP consist of patchy or diffuse bilateral ground-glass opacities, poorly defined small centrilobular nodules, and lobular areas of decreased attenuation and vascularity on inspiratory images and of air trapping on expiratory
images. The ground-glass opacities primarily reflect the presence of diffuse lymphocytic interstitial pneumonitis; minor degrees of organizing pneumonia, when present, also can contribute to this appearance. The poorly defined centrilobular nodules may be caused by cellular bronchiolitis, the predominantly peribronchiolar distribution of interstitial pneumonitis, or focal areas of organizing pneumonia. The lobular areas of decreased attenuation and air trapping are presumably caused by small-airway obstruction by cellular bronchiolitis or, less commonly, by constrictive bronchiolitis. In the appropriate clinical setting these findings strongly suggest the diagnosis.
- References
- 1. Silva CI, Churg A, Muller NL. Hypersensitivity pneumonitis: spectrum of high-resolution CT and pathologic findings. AJR Am J Roentgenol 2007;188(2):334-344.
2. Hirschmann JV, Pipavath SN, Godwin JD. Hypersensitivity pneumonitis: a historical, clinical, and radiologic review. Radiographics 2009;29(7):1921-1938.
- Keywords
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Lung, Interstitial lung disease, HP, ILD,