OBJECTIVE: To determine whether the subtypes of nonspecific interstitial pneumonia (NSIP) could be differentiated from other idiopathic interstitial pneumonias (IIPs) on the basis of findings on high-resolution computed tomography (CT). METHODS: Two observers evaluated the high-resolution CT findings in 90 patients with IIPs. The patients included 36 with NSIP, 11 with usual interstitial pneumonia (UIP), 8 with cryptogenic organizing pneumonia (COP), 10 with acute interstitial pneumonia (AIP), 14 with desquamative interstitial pneumonia (DIP) or respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), and 11 with lymphoid interstitial pneumonia (LIP). The NSIP cases were subdivided into group 1 NSIP (n = 6), group 2 NSIP (n = 15), and group 3 NSIP (n = 15). RESULTS: Observers made a correct diagnosis with a high level of confidence in 65% of NSIP cases, 91% of UIP cases, 44% of COP cases, 40% of AIP cases, 32% of DIP or RB-ILD cases, and 82% of LIP cases. Group 1 NSIP was misdiagnosed as AIP, DIP or RB-ILD, and LIP in 8.3% of patients, respectively. Group 2 NSIP was misdiagnosed as COP in 10% of patients, LIP in 6.7%, AIP in 3.3%, and DIP or RB-ILD in 3.3%. Group 3 NSIP was misdiagnosed as UIP in 6.7% of patients, COP in 6.7%, and DIP or RB-ILD in 3.3%. CONCLUSIONS: In most patients, NSIP can be distinguished from other IIPs based on the findings on high-resolution CT. Only a small percentage of patients with predominantly fibrotic NSIP (group 3 NSIP) show overlap with the high-resolution CT findings of UIP.

Nonspecific interstitial pneumonia in collagen vascular diseases: comparison of the clinical characteristics and prognostic significance with usual interstitial pneumonia.Sarcoidosis Vasc Diffuse Lung Dis. 2003 Oct;20(3):235-41.

BACKGROUND: Nonspecific interstitial pneumonia (NSIP) has recently been described as a distinct clinicopathological entity among idiopathic interstitial pneumonias (IIP), having more favorable prognosis than usual interstitial pneumonia (UIP). Although NSIP was initially reported to also occur in patients with interstitial pneumonia associated with collagen vascular diseases (IP-CVD), the prevalence of NSIP and its prognostic significance in IP-CVD remains to be determined. Thus, we attempted to clarify clinical characteristics and prognostic significance of NSIP in IP-CVD. METHODS: We histologically examined surgical lung biopsies from 43 patients with IP-CVD based on a current classification of interstitial pneumonias, and compared the clinical characteristics and prognostic significance of NSIP with UIP in IP-CVD. We also studied 98 patients with biopsy-proven NSIP and UIP in IIP, and compared the prognostic significance of histopathologic subclassification in IIP with that in IP-CVD. RESULTS: In IP-CVD, twenty-six patients (60%) were classified as NSIP, 17 (40%) as UIP. In contrast, 76 (77%) were categorized into UIP and 22 (23%) into NSIP of the patients with IIP. No significant difference in survival rates was observed between UIP and NSIP in IP-CVD (p = 0.3863), while, in IIP, NSIP has a significant better survival than UIP (p = 0.022). CONCLUSIONS: These results suggest that NSIP is more common histologic pattern than UIP in IP-CVD and, unlike in IIP, the prognosis of NSIP patients may not be different from that of UIP patients in IP-CVD.

The major histopathologic pattern of pulmonary fibrosis in scleroderma is nonspecific interstitial pneumonia.Sarcoidosis Vasc Diffuse Lung Dis. 2002 Jun;19(2):121-7.

BACKGROUND: The prognosis of pulmonary fibrosis associated with scleroderma (PF-SSc) has been reported to be significantly better than that of IPF. Because the nonspecific interstitial pneumonia-pattern (NSIP), a newly defined subgroup of idiopathic interstitial pneumonias (IIP), has better prognosis than the usual interstitial pneumonia pattern (UIP), we postulated that NSIP may occur more frequently than UIP in patients with scleroderma who develop fibrosis. METHOD: We reviewed the pathologic, radiologic and clinical outcomes in 19 patients with PF-SSc. Two pulmonary pathologists reclassified the histopathology of surgical lung biopsies (SLBx) and consensus diagnosis was achieved in all patients. RESULTS: Thirteen patients had NSIP, five had UIP, and remained one showed only nondiagnostic honeycombing. No significant difference was noted in the initial pulmonary function test (PFT), bronchoalveolar lavage (BAL) findings, or other clinical parameters between UIP and NSIP groups. Comparison of the clinical outcome of 12 patients who were followed for more than 12 months (mean: 34.5 +/- 26.0 months) suggested a better prognosis for NSIP than UIP. Five of the eight NSIP patients improved and three were stable, whereas in patients with UIP, one worsened and three were stable. CONCLUSION: NSIP seems to be the major histopathologic pattern in patients with PF-SSc.

Nonspecific interstitial pneumonitis: a new anatomoclinical entity among idiopathic diffuse interstitial pneumonias.Rev Mal Respir. 2001 Feb;18(1):25-33.

Nonspecific interstitial pneumonitis with fibrosis has been individualized within the group of idiopathic diffuse interstitial pneumonias by pathological criteria. It is differentiated from usual interstitial pneumonitis by the temporal uniformity of the lesions, a prominent inflammatory interstitial infiltration, and the absence of honeycombing. Clinical and functional symptoms are those of diffuse interstitial pneumonitis. An etiology may be found in about half the cases, including connective tissue disease, exposure to organic antigens, or recent acute lung injury. Computed tomography of the chest shows bilateral ground glass opacities, and alveolar opacities with a peribronchiolar or patchy distribution. Prognosis is rather good, since a majority of patients improve when treated with corticosteroids or with an association of corticosteroids and immunosuppressive drugs. These etiologic and prognostic features justify the individualization of nonspecific interstitial pneumonitis with fibrosis as a distinct clinicopathological entity.

Idiopathic nonspecific interstitial pneumonia: prognostic significance of cellular and fibrosing patterns: survival comparison with usual interstitial pneumonia and desquamative interstitial pneumonia.Am J Surg Pathol. 2000 Jan;24(1):19-33.

Nonspecific interstitial pneumonia (NSIP) has been proposed as a histologic subtype of idiopathic interstitial pneumonia with lung biopsy findings that are inconsistent with those of other idiopathic interstitial pneumonias. NSIP has a broad spectrum of histologic findings and a variable prognosis. The aim of this study was to determine whether it would be preferable to subdivide NSIP into cellular and fibrosing patterns. The authors classified lung biopsies from 101 patients with idiopathic interstitial lung disease as having histologic patterns of desquamative interstitial pneumonia (DIP), usual interstitial pneumonia (UIP), or cellular or fibrosing NSIP. Survival analysis was performed using the Kaplan-Meier method. Due to histologic, clinical, and survival similarities, the patients with idiopathic NSIP with lung biopsies that showed fibrosing as well as fibrosing and cellular patterns were combined into a single group of NSIP, fibrosing pattern. Of the 101 patients, 16 patients (9 women, 7 men) had idiopathic DIP; 56 patients (17 women, 39 men) had idiopathic UIP; 22 patients (7 women, 15 men) had idiopathic NSIP, fibrosing pattern; and 7 patients (2 women, 5 men) had idiopathic NSIP, cellular pattern. The patients had a mean age of 42, 51, 50, and 39 years respectively. Patients with idiopathic NSIP, cellular pattern had a better 5- and 100-year survival than those with idiopathic NSIP, fibrosing pattern (100% vs 90% and 100% vs 35% respectively, p = 0.027). Survival of patients with idiopathic UIP was worse than that of patients with idiopathic NSIP, fibrosing pattern (p = 0.014). The difference, however, was more evident at 5 years (43% vs 90%) than at 10 years (15% vs 35%). The 5- and 10-year survival of patients with idiopathic NSIP, cellular pattern and DIP was 100%, which was significantly better than that of patients with idiopathic UIP (p <0.0001). Based on these data, NSIP should be separated into cellular and fibrosing patterns, because these histologic patterns are associated with different clinical characteristics and prognoses.

A histologic pattern of nonspecific interstitial pneumonia is associated with a better prognosis than usual interstitial pneumonia in patients with cryptogenic fibrosing alveolitis.Am J Respir Crit Care Med. 1999 Sep;160(3):899-905.

This study aimed to investigate whether there was a difference in outcome related to histologic pattern in cryptogenic fibrosing alveolitis (CFA) and to see whether there were correlations between clinical and radiologic findings and histology. One hundred thirteen lung biopsies from consecutive patients taken for the diagnosis of diffuse lung disease were reviewed and reclassified using the Katzenstein and Myers criteria for interstitial pneumonias. Patients lacking full investigational data at presentation and those with conditions predisposing to lung fibrosis were excluded, leaving 15 patients diagnosed with nonspecific interstitial pneumonia (NSIP) and 15 with usual interstitial pneumonia (UIP). Clinical and radiologic findings at presentation and serial lung function information and survival status in November 1998 were compared for the two groups. Survival was found to be significantly greater in the NSIP group compared with the UIP group (p < 0.001). This could not be explained by differences in treatment. Patients with UIP showed a progressive deterioration in lung function whereas those with NSIP remained stable. CT scans of patients with UIP showed more fibrosis than those of patients with NSIP (p < 0.011). A histologic diagnosis of NSIP is associated with a better prognosis than UIP. This subclassification of CFA is clinically useful.

Nonspecific interstitial pneumonia. Individualization of a clinicopathologic entity in a series of 12 patients. Am J Respir Crit Care Med. 1998 Oct;158(4):1286-93.

Nonspecific interstitial pneumonia/fibrosis (NSIP) has recently been individualized within the group of idiopathic interstitial pneumonias mainly based on a pathologic pattern of temporally uniform lesions distinct from usual, desquamative, and acute interstitial pneumonia. We studied 12 consecutive patients with NSIP at lung biopsy done as a diagnostic procedure for idiopathic interstitial lung disease. The patients were six males and six females, aged 52.5 +/- 11.8 yr. In 8 of 12 cases the pathologic lesions consisted of both cellular interstitial inflammation and fibrosis, whereas only cellular inflammation was present in three cases, and fibrosis in one. Dyspnea, cough, inspiratory crackles, and squeaks were the most common symptoms and signs. Six cases were cryptogenic. An associated disorder or a presumed cause was present in the other six patients, including underlying connective tissue disease (n = 3), organic dust exposure (n = 2), and prior acute lung injury (n = 1). Lung function tests found a restrictive ventilatory defect (11/12), impairment of TLCO (11/11), and hypoxemia at rest (7/12). Chest X-ray showed infiltrative opacities in all cases. Computed tomography of the chest in 11 cases mainly showed ground glass opacities (9/11), patchy areas of alveolar consolidation (6/ 11), and thickening of interlobular septas (5/11). All patients were treated with corticosteroids, and seven with immunosuppressive agents. All patients were alive at last follow-up, 50 +/- 40 mo after diagnosis. Ten patients (83%) were clinically improved or stabilized. Thus, despite its heterogeneity, NSIP deserves to be individualized as an original clinicopathologic entity and should be clearly distinguished from usual interstitial pneumonia, especially because of a better prognosis.

Idiopathic nonspecific interstitial pneumonia/fibrosis: comparison with idiopathic pulmonary fibrosis and BOOP.Eur Respir J. 1998 ;12(5):1010-9.

Based on past difficulties in clinically differentiating patients with idiopathic pulmonary fibrosis (IPF), bronchiolitis obliterans-organizing pneumonia (BOOP), and nonspecific interstitial pneumonia/fibrosis (NSIP), which all manifest clinically as interstitial lung disease, experience with pathologically confirmed examples of the three diseases was reviewed to compare clinical profiles and prognosis and to define NSIP more clearly. Thirty-one patients (15 males and 16 females) were pathologically identified as NSIP and subclassified into either the cellular (n=16) or fibrotic group (n=15). All 31 patients were clinically considered to be idiopathic NSIP cases. Patients with idiopathic BOOP (n=16) and IPF (n=64) were compared with the NSIP patients. Subacute presentation of interstitial lung disease characterized both idiopathic NSIP and idiopathic BOOP. NSIP patients showed volume loss on a chest radiograph (29.0%) and honeycombing on a computed tomography scan (25.8%); these features were not found in BOOP patients. Bronchoalveolar lavage lymphocytosis was characteristic of both BOOP and NSIP. Two subgroups of NSIP can be recognized histologically: patients in the fibrotic group had a less favourable outcome than those in the cellular group. BOOP and NSIP had a more favourable outcome than IPF. In conclusion, idiopathic nonspecific interstitial pneumonia can be differentiated from other types of idiopathic interstitial pneumonia, both pathologically and clinically.

Nonspecific interstitial pneumonia/fibrosis. Histologic features and clinical significance. Am J Surg Pathol. 1994 Feb;18(2):136-47.

Sixty-four cases of interstitial pneumonia were identified that could not be classified into one of three main categories of idiopathic interstitial pneumonia. These cases, descriptively termed nonspecific interstitial pneumonia/fibrosis, were characterized by varying proportions of interstitial inflammation and fibrosis that appeared to be occurring over a single time span (i.e., the process was temporally uniform.) The most common presenting complaint was dyspnea for several months, and chest radiographs usually showed bilateral interstitial infiltrates. The prognosis was good with only five deaths due to progressive respiratory disease in 48 patients with known follow-up (11%). No deaths occurred in patients whose biopsies showed pure inflammation and no fibrosis. Nonspecific interstitial pneumonia must be separated from the three main forms of idiopathic interstitial pneumonia because of better prognosis and different treatment options. It should not be considered a specific disease, however, because it may have varying etiologies including underlying connective tissue diseases, organic dust or other exposures, and prior acute lung injury; less often, it may reflect a nonrepresentative biopsy of another process.

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