Nonspecific Interstitial Pneumonia (NSIP)

The histologic pattern of NSIP has two types: cellular and fibrotic, both of which may be found in patients with HP, as well as in those with collagen vascular diseases, drug-induced disease, and infection. NSIP may also be idiopathic. A diagnosis of HP should be considered in all patients with this pattern.


Cellular NSIP

The cellular type (shown here) has patchy, mild to moderate lymphocytic alveolitis with type II cell hyperplasia and focal organization of exudate throughout the biopsy. Granulomas are not a part of this disease.



Fibrotic NSIP: In contrast, the fibrotic type has a similar alveolitis in addition to loose or dense fibrosis that is temporally homogeneous. Architecture is preserved. Bronchiolar metaplasia, smooth muscle metaplasia, and honeycombing may be present.

In a study of 51 patients with NSIP, no patient with cellular disease died by 10 years following diagnosis, but for those with fibrosing disease, the survival was 90% and 35% at 5 and 10 years, respectively.


Travis W, Matsui K, Moss J, Ferrans V. Idiopathic nonspecific interstitial pneumonia: prognostic significance of cellular and fibrosing patterns. Survival comparison with usual interstitial pneumonia and desquamative intestitial pneumonia. Am J Surg Pathol 2000; 24:19-33. Abstract

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