Myofibroblasts proliferation of idiopathic and collagen vascular disorders associated nonspecific interstitial pneumonia.

Nonspecific interstitial pneumonia (NSIP has been recognized as a separate histological classification of interstitial lung disease. Similar features are found not only in idiopathic NSIP but also in NSIP associated with collagen vascular disorder (CVD‑NSIP. We examined the clinical symptoms laboratory findings and prognosis of 13 cases of idiopathic NSIP and 11 cases of CVD‑NSIP. Immunohistochemical staining was performed using the streptavidin/biotin/peroxidase method with anti‑α‑smooth muscle actin antibody. No differences in the distribution of clinical features laboratory findings and prognosis were observed between idiopathic NSIP and CVD‑ NSIP. In immunohistochemical staining of the fibrosing areas myofibroblasts were observed in 7 of 13 idiopathic NSIP cases but in 10 of 11 CVD‑NSIP cases. With regards to intra‑alveolar organization myofibroblasts were observed in all 10 CVD‑NSIP cases but they were observed in only 2 of 9 idiopathic NSIP cases. We found a significantly higher myofibroblast proliferation in the intra‑alveolar organization of CVD‑NSIP compared to idiopathic NSIP. Clinically idiopathic NSIP and CVD‑NSIP are similar but are pathologically different.