Pulmonary invasive fungal disease and bacterial pneumonia: a comparative study with high-resolution CT

Early diagnosis of invasive fungal disease (IFD) is challenging. High-resolution computed tomography (CT) may improve IFD diagnosis; however, there are no definitive imaging signs for differentiating between bacterial pneumonia and IFD.

We retrospectively evaluated CT images of 208 patients with IFD (n = 102) or bacterial pneumonia (n = 106). We classified pulmonary opacities as consolidations, ground-glass opacities (GGOs), or nodules and recorded the presence of perinodular ground-glass halos, reversed halo sign (RSH), and cavitation (crescent-shaped or not).

Consolidation appeared in 83.3% and 92.5% of patients with IFD and bacterial pneumonia, respectively. Multifocal non-segmental consolidation was more common in IFD (48%) than bacterial pneumonia (22.6%; P < 0.05). Segmental or subsegmental consolidation was more common in bacterial pneumonia (43.4%) than IFD (7.8%; P < 0.01). GGOs and nodules were more common in IFD than bacterial pneumonia (60.8% vs. 24.5% and 54.9% vs. 15.1%, respectively; each P < 0.05). Consolidation combined with GGO, nodules, or both GGO and nodules was more frequent in IFD than in bacterial pneumonia (each P < 0.05). Nodules with halo sign (n = 23) appeared in 22.5% and 3.8% of patients with IFD and bacterial pneumonia, respectively. Nodules with RSH appeared only in IFD, and those with cavitation appeared in 11.8% and 1.9% of patients with IFD and bacterial pneumonia, respectively.

Consolidation plus GGO and nodules or consolidation plus nodules is suggestive for IFD. Segmental or subsegmental consolidations are more frequent in bacterial pneumonia than in IFD. Large nodules, as well as nodules with halo sign or both small and large nodules, are related to IFD.