Idiopathic nonspecific interstitial pneumonia: an interstitial lung disease associated with autoimmune disorders?

Recent evidence suggests that idiopathic nonspecific interstitial pneumonia (iNSIP) is a distinct clinical entity amongst other idiopathic interstitial pneumonias, and some data seem to suggest a possible pathogenetic role of autoimmunity. The aim of the present study was to assess if iNSIP might represent an early lung manifestation of an autoimmune disease. After initial review of cases found in the medical records database by searching for the term "NSIP" (n = 63), 37 iNSIP cases were identified, and were re-evaluated using a dynamic integrated multidisciplinary approach. 27 cases with iNSIP were selected for the study. Mean ± sd age at first respiratory symptom was 54.2 ± 8 yrs, 70% were females, and 59% were never-smokers. At follow-up (mean ± sd 59.7 ± 29 months, range 12-138 months), autoimmune diseases occurred in 14 (52%) patients, with seven (26%) cases of autoimmune thyroiditis, six (22%) of undifferentiated connective tissue disease and three (11%) of connective tissue disease. Patients developing autoimmune diseases were older and more frequently never-smoking females. In >50% of patients diagnosed with iNSIP, evidence of autoimmune diseases develops within 2 yrs, suggesting a probable link between the clinical entity of iNSIP and autoimmune disorders.