nonspecific interstitial pneumonia (nsip)/ overlap or distinct entity: a case report from the national research institute of tuberculosis and lung disease (nritld)

background: in many cases of ild (interstitial lung disease), overlap diagnosis is considered. here, a few cases with diagnosis of a variety of ilds, where eventual open lung biopsy has been performed are selected. reference will be made to reliable sources to show that nsip can still be a variant of uip (usual interstitial pneumonia) with better treatment response and prognosis. case presentation: in case 1, there is a difference between the hrct(high resolution computed tomography) result (nsip pattern without fibrosis) and pathologic result (which includes fibrosing nsip more closely related to uip).case 2 shows obvious discord between hrct result (uip pattern) and pathologic result (nsip pattern). in case 3, there is again a discrepancy between hrct report (very mild architectural distortion suggestive for ild like nsip) and pathology report (destructed lung tissue with interstitial fibrosis suggestive of hp (hypersesitivity pneumonitis) and not nsip. conclusion: in this paper, we demonstrate that although nsip can be a distinct diagnosis in most cases, but in rare cases the distinction between the other kinds of ild especially uip and nsip in spite of full workup including tissue assessment can be very difficult.