ABSTRACT

Non-specific interstitial pneumonia (NSIP) is the second most frequent interstitial pneumonia following usual interstitial pneumonia (UIP). NSIP has two histopathological subtypes; celullar and fibrotic pattern. The infiltrations show temporal homogeneity in both patterns. Cellular NSIP is rare, characterized by ground glass infiltration on high resolution computed tomography (HRCT) and has a better response to corticosteroid treatment. Lower lung zones and peripheral areas are mostly involved in both patterns. Bilateral ground glass appearance, reticular infiltration, traction bronchiectasis are the frequent signs. Although it is specific for the disease, subpleural sparing sign may supports the diagnosis Honeycombing is rare. It is vital to differentiate NSIP from UIP as the two most frequent interstitial pneumonias. It is especially difficult to differentiate “probably UIP” which lacks honeycombing. Prominent honeycombing and subpleural distribution, without peribronchovascular involvement may ease the diagnosis for UIP. After recovering from the acute disease of coronavirus disease-2019 (COVID-19), some patients may still have cough and shortness of breath and there may be signs of fibrosis on HRCT. There is no consensus on how to call this episode of the disease but if the signs of the fibrotic disease continues more than 4 weeks after the onset is named as “longed COVID”, or stays more than 12 weeks is called “post-COVID syndrome”. Areas of ground glass, reticular pattern, crazy pavement, parenchymal bands, traction bronchiectasis/bronchioloectasis and very rarely honeycombing are the signs on HRCT.