Nonspecific Interstitial Pneumonia: Radiologic, Clinical, and Pathologic Considerations

Seth J. Ligerman, MD , Steve Groshong, MD, PhD ,Kevin K. Brown, MD David A. Lynch, MB

Nonspecific interstitial pneumonia (NSIP) has variable clinical, patho­logic, and radiologic manifestations. Cellular and fibrotic NSIP are the two main histologic subtypes and differ from one another in the de­gree of inflammation and fibrosis. It is important to differentiate NSIP from other diffuse lung diseases, especially usual interstitial pneumo­nia and hypersensitivity pneumonitis, owing to differences in prog­nosis and treatment. At high-resolution computed tomography, the most common findings suggestive of NSIP are lower lobe peripherally predominant ground-glass opacity with reticular abnormality, trac­tion bronchiectasis, and lower lobe volume loss. Nodules, cysts, and areas of low attenuation are uncommon and should point one toward other diagnoses. Because many cases of NSIP are associated with col­lagen vascular diseases, it is important to look for associated findings that may suggest an underlying collagen vascular disease. Given the difficulty clinicians, pathologists, and radiologists experience in mak­ing the diagnosis of NSIP, a group approach in which these specialists work together to reach a consensus diagnosis has the highest likeli­hood of achieving the correct diagnosis.