Summary

Although not common, herpes simplex virus (HSV) pneumonia can occur in immunocompromised patients. However, HSV pneumonia in immunocompetent hosts is very rare. The authors encountered a very rare case of severe HSV pneumonia in an immunocompetent host. The patient was an 85-year-old Japanese woman who presented with severe intractable pneumonia refractory to empirical antimicrobial therapy. Furthermore, the causative microorganisms remained unknown. Therefore, cytological examination of bronchoalveolar lavage fluid and protected brush biopsy of the lower respiratory tract were performed, which indicated herpes virus-infected cells with nuclear inclusions; PCR assay was positive for HSV DNA. Accordingly, the patient was diagnosed with HSV pneumonia. Her respiratory condition improved immediately after initiation of acyclovir monotherapy. In selected cases of intractable pneumonia refractory to standard antimicrobial therapy, the possibility of HSV pneumonia should be pursued.