Viral Pneumonia Requiring Differentiation from Acute and Progressive Diffuse Interstitial Lung Diseases

Ishiguro, Takashi; Kobayashi, Yasuhito; Uozumi, Ryuji; Takata, Naomi; Takaku, Yotaro; Kagiyama, Naho; Kanauchi, Tetsu; Shimizu, Yoshihiko; Takayanagi, Noboru

Two experienced radiologists (N. T. and T. K.) who were blinded to all clinical information independently reviewed the high-resolution computed tomography (CT) scans. These observers were asked about the presence of 17 findings: consolidation and GGOs (and their distribution), halo sign, inverted halo sign, cavitation, centrilobular nodules, mass, tree-in-bud sign, intralobular reticulation, honeycombing, diffuse bronchial wall thickening, pleural effusion, pneumothorax, mediastinal or hilar lymphadenopathy (minimal diameter " 10 mm), and cardiomegaly. The pathological findings were reviewed by a pathologist (Y. S). Then, in November 2018, a multidisciplinary diagnosis (final diagnosis) was established based on the laboratory, pathological and radiological findings, PCR results, and the clinical course by a review panel composed of pulmonary physicians (N. T and N. K), radiologists (T. K and N. T), and a pathologist (Y. S). A multidisciplinary diagnosis of viral pneumonia was made based on a positive virus PCR result, a compatible clinical course, and histological and radiological findings. In contrast, we considered that virus colonization had occurred if patients showed findings that were unlikely to indicate viral pneumonia, and an alternative diagnosis was made by a review panel. In the present study, patients with a diagnosis of AFOP, COP, or chronic eosinophilic pneumonia (CEP) were classified into the same category because of their overlapping histological patterns (3) . The diagnostic criteria of the established guidelines (3) (4) (5) were also considered in the multidisciplinary diagnosis. Causative microorganisms of pneumonia were defined using conventional methods that have been reported previously (6) .