Pathology of Fungal Rhinosinusitis: A Review

Abstract

Fungal rhinosinusitis (FRS) comprises a spectrum of disease processes that vary in clinical presentation, histologic appearances, and biological significance. FRS can be acute or chronic and is most commonly classified as non-invasive or invasive based on whether fungi have invaded into tissue. This manuscript will review the pathologic classification of FRS.

Keywords: Acute invasive fungal rhinosinusitis; Allergic fungal rhinosinusitis; Allergic mucin; Aspergillus; Fungal ball; Rhinosinusitis.

Fig. 1

Fungal ball a low power appearance of a maxillary sinus fungal ball from a 60 yo female. Fungal ball is composed of an entangled mass of fungal organisms (Hematoxylin and eosin; original magnification ×10). b Low power of a fungal ball showing a lamellated appearance, which can be confused with eosinophilic (allergic) mucin (EM). This fungal ball shows a layered appearance and pigmented fungal forms. Cultures grew Aspergillus niger (Hematoxylin and eosin; original magnification ×25). c Higher power of fungal ball showing an entangled mass of fungal organisms with very little inflammation (Hematoxylin and eosin; original magnification ×50). d Silver stain highlighting fungal organisms in a fungal ball (Grocott stain; original magnification ×100)

Fig. 2

Allergic fungal rhinosinusitis a low power of eosinophilic (allergic) mucin showing a layered appearance of mucin admixed with inflammatory cells and debris (Hematoxylin and eosin; original magnification ×10). b Eosinophilic mucin showing collections of eosinophils and sloughed epithelial cells (Hematoxylin and eosin; original magnification ×50). c Eosinophilic mucin showing eosinophils singly and in cluster (Hematoxylin and eosin; original magnification ×50). d Eosinophilic mucin showing Charcot–Leyden crystals (Hematoxylin and eosin; original magnification ×200)

Fig. 3

a Eosinophilic mucin often contains bacterial colonies (Hematoxylin and eosin; original magnification ×100). b Rarely, fungal organisms may be seen in eosinophilic mucin without use of specials stains. Cultures grew Curvularia sp. (Hematoxylin and eosin; original magnification ×100). c Silver stain of fungal organisms in eosinophilic mucin. Cultures grew Alternaria alternata (Grocott stain; original magnification ×200). d In situ hybridization for Aspergillus ribosomal RNA in eosinophilic mucin. Cultures confirmed A. fumigatus. (Nitroblue tetrazolium violet; original magnification ×100)

Fig. 4

Acute invasive fungal rhinosinusitis a low power view of infarcted sinonasal without significant inflammatory reaction in immunosuppressed patient with acute leukemia with acute invasive fungal rhinosinusitis Culture grew Rhizopus sp. (Hematoxylin and eosin; original magnification ×12.5). b Acute invasive FRS showing fungal organisms invading blood vessels and soft tissue. Cultures grew Aspergillus fumigatus (Hematoxylin and eosin; original magnification ×100). c Silver staining highlighting fungal hyphae in soft tissue in acute invasive FRS. Cultures grew A. fumigatus (Hematoxylin and eosin; original magnification ×100). d In situ hybridization (ISH) for Aspergillus ribosomal RNA. Note the extensive necrosis and only rare positive organisms. rRNA ISH is not always reliable on necrotic tissues (Fast red tetrazolium violet; original magnification ×100)

Fig. 5

Chronic invasive granulomatous fungal rhinosinusitis a, b Granulomatous reaction toward Aspergillus flavus in patients with chronic invasive granulomatous fungal rhinosinusitis (Hematoxylin and eosin; original magnification ×25 for a and ×100 for b)

Fig. 6

Chronic invasive fungal rhinosinusitis a low power of inflamed and fibrotic sinonasal mucosa in liver transplant patient with chronic invasive fungal rhinosinusitis (Hematoxylin and eosin; original magnification ×12.5). b, c Chronic invasive FRS with extensive sinonasal mucosal necrosis/infarction with visible fungal organisms in liver transplant patient with symptoms greater than 3 months duration. b Fungi within blood vessels (Hematoxylin and eosin; original magnification ×100). d Silver stain shows fungal hyphae infiltrating sinonasal mucosa in chronic invasive FRS (Hematoxylin and eosin; original magnification ×50)