ABSTRACT
Nonspecific interstitial pneumonia (NSIP) represents a distinct histopathologic
category of interstitial lung disease (ILD), a disease associated with uniform-
appearing cellular histology characterized by temporal homogeneity. This rep-
resents a distinguishing histopathologic feature from usual interstitial pneumonia
(UIP), a disease characterized by new and old lesions or temporal heterogeneity.
Following UIP, the histopathologic pattern of idiopathic pulmonary fibrosis
(IPF), NSIP represents the second most prevalent subtype of the idiopathic
interstitial pneumonias (IIPs).
