Current Status of Idiopathic Nonspecific Interstitial Pneumonia

Abstract

Pulmonary pathologists were aware of cases of idiopathic interstitial pneumonia (IIP) that morphologically did not fit Liebow's classification scheme. These cases were labeled as "cellular interstitial pneumonia" or "chronic interstitial pneumonia not otherwise specified." The term nonspecific interstitial pneumonia (NSIP) was first used in relation to a pattern of lung interstitial inflammation seen in association with human immunodeficiency virus (HIV) infection. In 1994 NSIP was used to indicate a group of subacute or chronic interstitial pneumonias characterized morphologically by interstitial inflammation or fibrosis or both, with preservation of the lung architecture and the absence of typical findings for any of the other main categories of IIP (mainly usual interstitial pneumonia, desquamative interstitial pneumonia, and bronchiolitis obliterans organizing pneumonia). Although these patients presented with "nonspecific" lung histology (categorized as cellular and fibrotic variants), and with a broad spectrum of associated clinical conditions, such as connective tissue diseases (CTDs), environmental exposure, and previous acute lung injury, they showed some peculiar clinical aspects, including favorable response to corticosteroid treatment and overall good prognosis.The clinical and radiographic profiles were better defined in the last decade. The NSIP pattern is the histological background of a subacute/chronic interstitial pneumonitis that may be observed in many conditions, including CTD, drug-induced lung disease, hypersensitivity pneumonitis, slowly healing diffuse alveolar damage (DAD), relapsing organizing pneumonia, occupational exposure, immunodeficiency (mainly HIV infection), graft versus host disease (GVHD), familial pulmonary fibrosis, immunoglobulin G4 (IgG4)-related sclerosing disease, with or without overlap features with Rosai-Dorfman disease, multicentric Castleman disease, and myelodysplastic syndrome. Rarely, NSIP is the histology recognized in patients with idiopathic interstitial pneumonitis, in whom efforts to find potential causative exposures are futile. This entity occurs mostly in middle-aged, never-smoker women, with a likely association with an autoimmune background. High-resolution computed tomographic (HRCT) scans typically demonstrate ground-glass attenuation with a bibasilar distribution, or in the fibrotic variant, ground-glass attenuation along with reticular lines and traction bronchiectasis. The prognosis is good compared with idiopathic pulmonary fibrosis (IPF), and therapeutic options include mainly corticosteroids and immunosuppressive agents. Recently a more precise definition of clinical profiles and radiographic findings of idiopathic NSIP allows consideration of less invasive diagnostic procedures (bronchoalveolar lavage, transbronchial lung biopsy). Better understanding of pathogenetic mechanisms might widen the therapeutic horizon giving a role to new therapeutic options in more severe cases.

Idiopathic Pulmonary Fibrosis: Diagnosis and Prognostic Evaluation

“…Diagnostic clues derived from the clinical reasoning are not included in the diagnostic approach of current guidelines. Specifically idiopathic nonspecific interstitial pneumonia is an entity that mainly affects nonsmoking women in their 6th decade with an ‘autoimmune background' who may develop a full-blown collagen vascular disease during follow-up [53,54]. A typical CT scan feature, which unfortunately does not present in all cases, is sparing of the subpleural regions.…”

Genome Sequencing of Idiopathic Pulmonary Fibrosis in Conjunction with a Medical School Human Anatomy Course

“…The patient's somewhat acute presentation following onset of flu-like symptoms is perhaps consistent with an antecedent viral infection, which is a setting in which NSIP has been known to occur [34]. In principle, genomic sequence analysis could permit identification of pathogens that might have triggered putative immune responses and ultimately set the stage for development of fibrotic lung disease.…”

Pneumonia, Acute Respiratory Distress Syndrome, and Early Immune-Modulator Therapy

“…There are critical organ-specific diseases that can seriously damage whole organs within a short period of time, including ARDS of the lungs. Examples of these critical organ-specific diseases are fulminating hepatitis (liver), acute myocarditis (heart), rapidly progressive glomerulonephritis (kidneys), acute necrotizing pancreatitis (pancreas), acute encephalopathy (including Reye syndrome) (brain), Waterhouse–Friderichsen syndrome (adrenal glands), toxic epidermolysis (skin), and acute hemorrhagic shock syndrome [56,57,58,59,60,61,62,63,64]. These organ-specific diseases are associated with more than one etiologic agent, including various pathogens.…”