Prognosis of subacutely progressive interstitial pneumonia depends on the presence of focal usual interstitial pneumonia

: A retrospective follow-up study was conducted on patients with subacutely progressive interstitial pneumonia who underwent surgical biopsy. Pathologically, they were subclassified into subacute interstitial pneumonia (SIP) and SIP + F, which consisted of an SIP lesion and a focal usual interstitial pneumonia. The SIP group consisted of 35 cases and the SIP + F group, of 15 cases. The majority of patients in both groups were female and complained of dyspnea. Both groups showed increased neutrophil counts (8.8%, 6.3%), eosinophils (6%, 5.6%), and lymphocytes (43.1%, 42.3%) in bronchoalveolar lavage. Chest radiography generally demonstrated predominant lower lobe involvement together with shrinkage in both groups, and differentiation of the two was difficult before biopsy. All but one improved temporarily with steroid therapy, or spontaneously, in both groups. On further observation after temporary improvement, 27 cases (82%), did not show any worsening and 6 cases (18%) showed worsening (including death) in the SIP group, while 6 cases (43%) showed no worsening, though 8 cases (57%) worsened in the SIP + F group. Deaths in either group that were not related to the original diseases were excluded from the statistical analysis. We concluded that the presence of focal usual interstitial pneumonia in SIP lesions affects prognosis in patients with subacutely progressive interstitial pneumonia.