NSIP

2 types (a) cellular NSIP
(b) Fibrotic NSIP (more common)
Fibrosis may involve alveolar septa, peribronchivascular interstitium, interlobular septa and visceral pleura.
Prognosis of fibrotic NSIP is worse , cellular NSIP has good prognosis.
HRCT finding may show both, airspace and interstitial patterns

1. NSIP Dr. Vrishit Saraswat Resident Department of Radiodiagnosis

2. NSIP Homogenous expansion of alveolar walls by varying amounts of interstitial inflammation and fibrosis. Relative temporal and geographical homogenicity . Women Non smoker Age less than 50 yrs Honeycombing is uncommon

3. 2 types (a) cellular NSIP (b) Fibrotic NSIP (more common) Fibrosis may involve alveolar septa, peribronchivascular interstitium , interlobular septa and visceral pleura. Prognosis of fibrotic NSIP is worse , cellular NSIP has good prognosis. HRCT finding may show both, airspace and interstitial patterns.

4. Typical HRCT findings- GGO , irregular linear opacity ( reticulations ), traction bronchietasis . GGO found in patients , changed into reticular opacity after few years. Honeycombing id present, tends to be mild Lower lobe predominance is common. U pper lobe is uncommon in NSIP and should suggest another diagnosis (chronic HP, sarcoidosis )

5. Characteristic finding of NSIP is relative sparing of the immediate subpleural lung in dorsal region of lower lobe. CT findings tend to improve with treatment in pts who mainly have GGO predominance (cellular; airspace) than pts who have predominant fibrosis on previous scans. The majority of patients who show progression of fibrosis on follow up ; a significant minority progress to UIP pattern.

6. Abnormalities seen on HRCT in NSIP can mimic with :- (a) UIP (predominantly lower lobe reticulations) (b) HP, RB-ILD (predominantly GGO) (c) BOOP(when there is extensive consolidation) Multivariate logistic regression analysis showed that the most useful finding for distinguishing IPF from NSIP was the extent of honeycombing . The average extent of honeycombing was 4.4% of parenchyma in IPF and less than 1% in NSIP.

7. Various studies demonstrate that HRCT allows distinction of NSIP from IPF and chronic HP in many patients. However, although the presence of predominantly peripheral and basal honeycombing in the appropriate clinical setting often allows a confident diagnosis of IPF on HRCT, a confident diagnosis of NSIP requires surgical biopsy and a dynamic multidisciplinary approach with input from clinicians, radiologists, and pathologists . It is important to note that even a histologic diagnosis of NSIP does not establish a final diagnosis.

8. HRCT finding of patchy or subpleural ground-glass opacity, with or without reticulation , should suggest a likely diagnosis of NSIP rather than UIP. Generally, lung biopsy is recommended in this setting.

9. In cases where diagnosis cannot be made because of overlap of CT and histological findings; Chrug & Muller proposed a three seperations on HRCT for chronic interstitial diseases. Air space opacification (GGO or consolidation) – COP / Cellular NSIP/DIP / Sub acute HP – good prognosis. Diseases manifesting extensive GGO with mild reticulation(>25% of lung parenchyma)- mixed NSIP / Chronic HP. Predominant Reticulations – fibrotic NSIP/ UIP.