Evidence for a 'preinvasive' variant of fungal sinusitis: Tissue invasion without angioinvasion

Abstract

Clinical experience has suggested the existence of an intermediate form of fungal sinusitis between the categories of non-invasive fungal sinusitis (non-IFS) and invasive fungal sinusitis (IFS). This fungal sinusitis variant demonstrates unhealthy mucosa by endoscopy with fungal invasion, but lacks angioinvasion microscopically, representing what clinically behaves as a 'pre-invasive' subtype of fungal sinusitis. Unlike non-IFS disease, patients with pre-invasive fungal sinusitis were still felt to require anti-fungal medications due to histologic presence of invasive fungus. While sharing some clinical features of IFS, these 'intermediate' patients were successfully spared extended and repeated surgical debridements given the microscopic findings, and have been successfully treated with shorter courses of antifungal therapy. These select patients have had favorable outcomes when managed in a judicious and semi-aggressive manner, in an undefined zone between the treatments for routine fungal ball and aggressive IFS.

Keywords: Antifungal therapy; Chronic rhinosinusitis; Fungal ball; Fungal sinusitis; IFS; Immunocompromised; Immunosuppressed; Invasive fungal sinusitis; Visual loss.

Fig. 1

CT and MRI imaging for Case #1. A: CT-scan coronal view without contrast demonstrating complete opacification of the left sphenoid sinus; no speckled calcifications noted; B: Coronal MRI T1 with contrast demonstrating left sphenoid central signal hyperintensity with surrounding rim of hypointensity; C: MRI T2 coronal view demonstrating loss of signal intensity within the left sphenoid, suggestive of fungal sinusitis and possible IFS.

Fig. 2

CT and MRI imaging for Case #2. A: Axial CT scan without contrast demonstrating left sphenoid opacification and bony erosion over the carotid. 1–2 spots of calcification can be seen; B: MRI T1 with contrast coronal view demonstrating left sphenoid opacification with heterogeneous signal pattern; C: MRI T2 axial view demonstrating complete signal drop out within left sphenoid, suggestive of dense left sphenoid fungal sinusitis and possible IFS given crescendo in symptoms.

Fig. 3

Histologic assessment of fungal invasion. A: Hematoxylin/eosin (H&E) and Grocott-Gomori methenamine silver (GMS) stained histologic sections demonstrating presence of submucosal fungal species without angioinvasion; B: Additional H&E and GMS stained sections as A with small blood vessels included and without evidence of fungal angioinvasion; C and D: For comparison, H&E stained histologic sections from 2 different patients with ‘classic’ invasive fungal sinusitis, demonstrating histologic angioinvasion. Representative images at 20- and 40-fold magnification are shown.