ARRS 2022 Abstracts


E1384. The Different Faces of Fungal Sinusitis
  1. George Vilanilam; University of Arkansas for Medical Sciences
  2. Shruti Kumar; University of Arkansas for Medical Sciences
  3. Sanjaya Viswamitra; University of Arkansas for Medical Sciences
  4. Surjith Vattoth; University of Arkansas for Medical Sciences
Fungal sinus disease is a common but often misdiagnosed disease process. It can present as a slowly progressing extra mucosal fungal ball, a non-invasive disease as in allergic fungal sinusitis, or fulminant infection with vascular invasion as in invasive fungal sinusitis. Recognizing imaging features characteristic of these conditions is vital, particularly since they are distinct entities with different managements and prognoses.

Educational Goals / Teaching Points
The goal of this exhibit is to recognize characteristic imaging features of the spectrum of fungal sinus disease, thereby alerting the surgeon to obtain appropriate samples and prompting the pathologist to use of specialized stains for the detection of fungal elements.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
For allergic fungal sinusitis, imaging demonstrates opacification and expansion of multiple sinuses with inspissated material across both CT and MRI. The inspissated material appears centrally hyperdense and peripherally hypodense on CT with bony de-ossification. MRI characteristically demonstrates hypointensity on T2-weighted imaging (WI) due to fungal concretions and large concentrations of electromagnetic elements (iron and manganese). For invasive fungal sinusitis, imaging demonstrates sinus opacification with focal bone erosion, adjacent soft tissue infiltration, and characteristic non-enhancing mucosa. The earliest finding on CT is unilateral soft tissue thickening. On MRI the non-enhancing, hypointense mucosa corresponds to necrotic eschar and the contrast-enhancing mucosa and surrounding soft tissues correspond to inflammatory changes. For fungal mycetoma, imaging typically demonstrates involvement of a single sinus with high-density material containing fine, round-to-linear matrix calcifications. CT demonstrates thick sclerotic walls from chronic inflammation. MRI demonstrates hyperintensity on T1-WI due to the absence of free water in the mycetomatous mass and T2 hypointensity due to paramagnetic metals (iron, magnesium, and manganese). For fungal colonization, imaging demonstrates sinus mucosal thickening with reactive hyperostosis of the sinus walls. CT demonstrates high-density material containing heavy metals. On MRI there is variable signal of retained secretions on T1- and T2-WI based on water and protein content. The teaching point is to not mistake low T2 signal for air and that T2 appearance must be correlated with T1-WI and CT if available.

Fungal sinus disease is a diverse and easily misdiagnosed entity that must be recognized by the radiologist in a timely manner to facilitate accurate diagnosis and management. Specifically, in angioinvasive fungal sinus disease, the lack of mucosal enhancement is more diagnostic than enhancement.