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

In the present study, AFOP, COP, and CEP were found to be the most frequently misdiagnosed ILDs. Various influenza-associated pneumonias that show similar CT patterns to COP, AFOP, and AIP have been reported (19) , and a previous report focusing on primary influenza suggested the (20) . Then CT findings in our patients with viral pneumonia were compatible with the diagnosis, but the spectrum of CT findings encountered in viral pneumonia (21-23) is non-specific and is also found in the above ILDs. Physicians should include viral pneumonia in the differential diagnosis of imaging patterns that are suggestive of these diseases. In addition, the histological findings in our patients with viral pneumonia, which were mostly obtained via TBLB, were also non-specific (24) , and it was difficult to suspect viral pneumonia on the basis of histological findings alone. In most patients with viral pneumonia, treatment is mainly supportive care. The efficacy of NIs is partially reported in influenza-associated pneumonia (25) , NIs were effective in some of our patients. It is recommended that NIs be administered within 48 hours from the onset of symptoms; however, NIs administered after this 48-h period were effective in some of our patients. Regarding the treatment of viral infections other than influenza virus, immunoglobulin therapy (pegylated interferon-alpha2A) for rhinovirus, the potential efficacy of palivizumab for RSV, ribavirin (a guanosine analogue) therapy for RSV and hMPV, and cidofovir (the nucleoside analogue of cytidine monophosphate) for adenovirus infection have been reported (26) . However, the efficacy of these treatments for primary viral pneumonia is unknown. Severe cases require aggressive treatment, including antiviral therapy; however, one problem we found was that viral pneumonia was not infrequently caused by multiple viruses. Similar results have been reported elsewhere (27) . It may be useful for physicians to test for multiple viruses simultaneously when considering antiviral therapy.