Herpes-Simplex-Virus 1 pneumonia in the immunocompromised host: high-resolution CT patterns in correlation to outcome and follow-up.

Objective: To identify the high-resolution CT (HRCT) patterns of Herpes-Simplex-Virus 1 (HSV) pneumonia in immunocompromised patients and correlate findings to outcome and radiographic follow-up until death or complete resolution of findings.

Patients And Methods: HRCT data-sets and plain radiographic follow-ups were reviewed in 25 immunocompromised patients with confirmation of new onset HSV-1 pneumonia. Pattern and distribution of abnormalities was assessed by two chest radiologists and findings evaluated regarding outcome and dynamics.

Results: The most frequent CT abnormalities included ground-glass attenuation (n=18; 72%) in a bilateral, symmetric and random distribution, air-space consolidations (n=13; 52%) in a bilateral, asymmetric and peribronchial allocation and interlobular septal thickening (n=6; 24%). When classified by leading HRCT pattern, patients subdivided into distinct groups with either dominant ground-glass attenuation or air-space consolidation. Six patients died after a median 8 days of diagnosis; the median interval until complete radiographic remission of pathology was 20 days. Pre-dominance of air-space consolidations was associated with significant delay of improvement (p=0.023); however, patient outcome was comparable in both subgroups (p=0.9).

Conclusion: Diagnosis of HSV pneumonia is challenging and requires familiarity with two distinct HRCT patterns: predominance of ground-glass opacities or air-space consolidations. Whilst the two forms are not linked to patient outcome they demonstrate a variable dynamic at follow-up.