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

The differential diagnoses of the 109 patients on presentation, as considered by the respiratory physicians, included Sixty of the patients were PCR-positive. Among these patients, 7 were finally re-diagnosed as having diseases other than viral pneumonia (Fig. 1) . In six patients, pulmonary shadows relapsed several times with the tapering of corticosteroids during post-discharge follow-up. The histological and radiological findings and clinical courses were compatible with those of OP, and the patients' final diagnoses were COP (n=5) or radiation-primed OP (n=1). BALF eosinophilia (44.6%) was found in one of these 7 patients. The patient's chest CT showed pulmonary consolidation, interlobular septal thickening, and pleural effusion. Several days before the onset of symptoms, the patient was exposed to smoking, and these findings were compatible with acute eosinophilic pneumonia. The final diagnoses included viral pneumonia in 53 patients and diseases other than viral pneumonia in 56 patients [unclassifiable IP, n=2; AFOP, COP, or CEP, n=11; radiation-primed OP after breast cancer, n=1; acute eosinophilic pneumonia, n=3; acute HP, n=3; CTD-ILD, n=12 (polymyositis, n=3; dermatomyositis, n=2; amyopathic dermatomyositis with MDA5 antibody, n=2; antisynthetase syndrome, n=5; and rheumatoid arthritis, n=1), DILD, n=18, and pneumonia due to unknown pathogens, n= 4]. Patients with a final diagnosis of viral pneumonia had been diagnosed on discharge as having COP/CEP/AFOP (n= 22), AIP (n=5), CTD-ILD (n=3), unclassifiable IP (n=2), pneumonia (n=20), and DILD (n=1). The rates at which a final diagnosis of viral pneumonia was made for each diagnosis at discharge were as follows: AIP, AFOP, and COP, 62.5% (5 of 8 Among the 40 control BALF samples obtained from patients with chronic lung diseases, 3 (7.5%) patients had positive viral PCR results (HPeV in a patient with sarcoidosis, rhinovirus in a patient with sarcoidosis, and rhinovirus in 1 patient with fibrotic non-specific IP).