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Non-specific interstitial pneumonia

Dr Yuranga Weerakkody et al.

Non-specific interstitial pneumonia (NSIP) often refers to a morphological pattern of interstitial lung disease.

Epidemiology

Typically tends to present in middle aged adults (40-50 years of age ¹)

Pathology

Temporal and spacial homogeneity is a key feature. It can be divided into 2 pathological sub types ⁸.

fibrotic non specific interstitial pneumonia - more common
cellular non specific interstitial pneumonia - less common

Associations

Primarily idiopathic but the morphological pattern can be seen in association with a number of conditions

connective tissue disorders

other auto immune diseases
drug induced lung disease: especially chemotherapy agents ⁴

If there is no underlying cause it is termed idiopathic NSIP - which is now considered a specific sub entity

Radiographic features

Plain film / chest radiograph

Can be normal in early stages. There may be consolidation in a patchy, reticulonodular or mixed distribution. A bilateral pulmonary infiltrative pattern may be seen in those with advanced disease.

HRCT chest

Imaging features can overlap between cellular and fibrotic types. Involvement tends to be sub-pleural and generally symmetrical although lacks an apico-basilar gradient

Common manifestations include:

patchy ground-glass opacities combined with irregular linear or reticular opacities : tends to be a dominant feature: can be symmetrically or diffusely distributed in all zones or display a basal predominance
reticular opacities
irregular linear opacities - with NSIP with fibrosis ^6-7
thickening of bronchovascular bundles - with NSIP with fibrosis ⁶
scattered micronodules
in advanced disease