The many faces of fungal disease of the paranasal sinuses: CT and MRI findings

Abstract

The prevalence of fungal rhinosinusitis has increased worldwide over the last two decades. Fungal rhinosinusitis includes a wide variety of infections, from relatively innocent to rapidly fatal processes. Fungal infection may be one of the most challenging forms of sinonasal pathology to manage, especially the invasive forms, which have high mortality rates. Therefore, it is essential to correctly diagnose and classify fungal disease of paranasal sinuses in order to accurately predict prognosis and implement effective therapy. This essay describes the different manifestations of fungal sinusitis on computed tomography and magnetic resonance imaging to optimize differentiation, and includes correlation with the pathologic classifications.

Extrasinonasal infiltrative process associated with a sinonasal fungus ball: does it mean invasive fungal sinusitis?

“…Differentiation between chronic IFS and malignant neoplasm may not be possible on imaging findings (3). Chronic invasive granulomatous fungal sinusitis is a fungal infection characterized by noncaseating granulomas in the tissues (10). The disease has been primarily found in Africa and Southeast Asia and is similar clinically and radiographically to chronic IFS (3,10,20).…”

“…Chronic IFS is a slowly progressive fungal infection with a time course longer than 12 weeks (3,10). Affected patients are usually immunocompetent, but those with a low level of immunocompromise are also susceptible.…”

“…Chronic invasive granulomatous fungal sinusitis is a fungal infection characterized by noncaseating granulomas in the tissues (10). The disease has been primarily found in Africa and Southeast Asia and is similar clinically and radiographically to chronic IFS (3,10,20). Irrespective of the true nature of the infiltrative processes, i.e., IFS or NFIP, none of the cases in our series had imaging evidence of a mass formation, which has been reported as an important feature of chronic IFS, associated with the extrasinonasal infiltrative process, except for the FB itself.…”

A Radiological Profile of Fungal Sinusitis

“…Intracranial or extrasinus soft tissue involvement is either through sinus wall bone erosion or hematogenous spread in case of an intact bony wall which may lead to life-threatening complications such as internal carotid artery invasion, cavernous sinus thrombosis, intracranial abscesses, infarct, and hemorrhage [4,7]. The typical findings of AFIFRS on CT scan as determined by literature are (1) opacification of involved sinuses (2) focal bony erosion (3) sinus and lateral nasal wall soft tissue thickening (4) premaxillary fat pad infiltration due to vascular infiltration (5) hyperattenuation due to the presence of fungal secretions and (6) heterogenicity due to the presence of fungal hyphae, trace metals, depleted water or elevated protein content or a combination of all [4,[7][8][9] The early features on CT scan are consistent with any form of sinus inflammation as it shows nasal soft tissue thickening which is not specific to AFIFRS, however, late features of retroantral infiltration of the fat pad, extrasinus and intracranial involvement are more specific for AFIFRS [4,10]. DelGaudio et al [11].…”

Cone-Beam Computed Tomography in the Diagnosis of Nasal Cavity Fungus Ball

“…possibility to establish a diagnosis of the fungus ball only on the basis of CT data are described [8]. This is due to the presence of certain CT -features of the fungus ball -a heterogeneous density of formation due to combination of contents soft tissue density (the presence of fungus ball masses and inflamed mucosa) with high-density inclusions relevant to the deposition of calcium salts and the formation of mycotic stones [9][10][11].…”