Nonspecific interstitial pneumonia
 Discussion of Nonspecific interstitial pneumonia
- NSIP is one of the most common histologic findings in patients with idiopathic intersitial pneumonias.
- NSIP is associated with a variety of imaging and histologic findings, and the diagnostic approach is highly challenging. However, the distinction of NSIP from UIP is needed, given the better response to corticosteroids seen in a subgroup of patients with NSIP.
- The typical patient with NSIP is between 40 and 50 years old and is usually about a decade younger than the patient with IPF.
- Symptoms of NSIP are similar to those of IPF but usually milder.
- Patients present with gradually worsening dyspnea over several months, and they often experience fatigue and weight loss.
- Treatment of patients with NSIP is based on the use of systemic corticosteroids in combination with cytotoxic drugs, such as cyclophosphamide and cyclosporin.
- The histologic pattern of NSIP is characterized by temporally and spatially homogeneous lung involvement. This homogeneity is a key feature in differentiating the NSIP pattern from the UIP pattern.
 Imaging Findings for Nonspecific interstitial pneumonia
 Plain film
- In patients with early NSIP, the chest radiograph is normal.
- In advanced disease, bilateral pulmonary infiltrates are the most salient abnormality.
- The lower lung lobes are more frequently involved, but an obvious apicobasal gradient, as seen in UIP, is usually missing.
- High-resolution CT typically reveals a subpleural and rather symmetric distribution of lung abnormalities.
- The most common manifestation consists of patchy ground-glass opacities combined with irregular linear or reticular opacities and scattered micronodules.
- In advanced disease, traction bronchiectasis and consolidation can be seen; however, ground-glass opacities remain the most obvious high-resolution CT feature.
- Subpleural cysts are another feature of NSIP, but compared to those of UIP, these cysts are smaller and limited in extent. The term "microcystic honeycombing" is used for these cystic changes in NSIP, as opposed to the macrocystic honeycombing seen in UIP.
- Owing to the substantial overlap of high-resolution CT patterns, the major CT differential diagnosis for NSIP is UIP. The key CT features that favor the diagnosis of NSIP over UIP are homogeneous lung involvement without an obvious apicobasal gradient, extensive ground-glass abnormalities, a finer reticular pattern, and micronodules.
 See Also
 External Links
- Christina Mueller-Mang, Claudia Grosse, Katharina Schmid, Leopold Stiebellehner, and Alexander A. Bankier. What Every Radiologist Should Know about Idiopathic Interstitial Pneumonias. RadioGraphics 2007 27: 595-615.