NSIP Fibrotic form

Fibrotic non-specific interstitial pneumonitis is a
- histological subtype of non-specific interstitial pneumonitis (NSIP).
  - chronic interstitial inflammation
    - In cellular NSIP the alveolar septa are thickened by infiltrates of lymphocytes and plasma cells,
    - in fibrotic NSIP the thickening is mainly due to
    - dense collagen accumulation.
    - The fibrosis may involve the
      - alveolar septa,
      - peribronchiolar interstitium,
      - interlobular septa, and
      - visceral pleura.
        
        possible areas of organizing pneumonia
        
        usually focal and mild.
      - fibroblastic foci
      - Presence of prominent bronchiolectasis as aopposed to dominant ground glass helps distinguish the 2 entitis
      - ie cellular vs fibrotic
      - Sometimes it is a mixture
  - obscured by interstitial fibrosis (
  - occasional focal honeycomb fibrosis