1. Fungal Sinusitis: An Overview
Cade Martin, MD

2. Fungal Sinusitis
400,000 known fungal species or which 400 are human pathogens and 50 of which cause systemic or CNS infection
Clinical presentation, imaging features, and treatment differ based on type of fungal sinusitis
Broadly categorized into invasive and noninvasive

3. Fungal Sinusitis Invasive Noninvasive
Presence of fungal hyphae within the mucosa, submucosa, bone, or blood vessels of the paranasal sinuses
Noninvasive
Absence of fungal hyphae within the mucosa and other structures of the paranasal sinuses

4. Fungal Sinusitis - Classification
Invasive
Acute Invasive Fungal Sinusitis
Chronic Invasive Fungal Sinusitis
Chronic Granulomatous Invasive Fungal Sinusitis
Noninvasive
Allergic Fungal Sinusitis
Fungus Ball (fungus mycetoma)

5. Acute Invasive Fungal Sinusitis
Most lethal form of fungal sinusitis – mortality 50-80%
Rare in immunocompetent patients
Two clinical populations
Poorly controlled Diabetics – ususally caused by fungi of order Zymocycetes (Rhizopus, Rhizomucor, Absidia, and Mucor)
Immunocompromised with severe neutropenia (chemotheraphy patients, BMT, organ transplants, AIDS) – Aspergillus accounts for 80% of infection in this group

6. Acute Invasive Fungal Sinusitis - Clinical
Necrotic nasal septum ulcer (eschar), sinusitis, rapid orbital and intracranial spread resulting in death
Angioinvasion and hematogenous dissemination common
Present with fever, facial pain, nasal congestion, epistaxis progressing to proptosis, visual disturbance, headache, mental status changes, seizures as spread occurs
73% of patients with intracranial spread die

7. Acute Invasive Fungal Sinusitis - Imaging
Noncontrast CT
Severe unilateral nasal cavity soft tissue thickening is most consistent (but nonspecific) early CT finding
Hypoattenuating mucosal thickening within lumen of paranasal sinus with rapid aggressive bone destruction of sinus walls occurs as disease progresses
Often unilateral involvement of ethmoids, sphenoids
These Fungi can also spread along vessels with spread beyond the sinus with intact bony walls
Intracranial extension can result in cavernous sinus thrombosis, carotid artery invasion, occlusion, or pseudoaneurysm

8. Acute Invasive Fungal Sinusitis - CT
Unilateral ethmoid involvement with bone destruction, intraorbital spread and proptosis

9. Acute Invasive Fungal Sinusitis - MRI
Aspergillus involving the sphenoid sinus with invasion of the left cavernous sinus, thrombosis, extension to the left sylvian fissure and infratemporal fossa with cerebral infarctions.

10. Acute Invasive Fungal Sinusitis - Imaging
MRI – better for evaluating intracranial and intraorbital extension
Evaluate for inflammatory change in orbital fat and extraocular muscles
Obliteration of periantral fat is a subtle sign of extension
Leptomeningeal enhancement progressing to cerebritis and abscess

11. Aspergillus in left maxillary sinus with extension anterior and posterior to the retroantral space. There is diffuse involvement of the muscles of mastication.

12. Acute Invasive Fungal Sinusitis - Treatment
Aggressive surgical debridement and systemic antifungal therapy
Reversal of underlying cause of immunosuppression if possible
Recovery from neutropenia is most predictive of survival
Intracranial spread is most predictive of mortality

13. Chronic Invasive Fungal Sinusitis
Inhaled fungal organisms deposited in nasal passageways and paranasal sinuses
Progression over months to years with fungal organisms invading mucosa, submucosa, blood vessels, and bony walls
Organisms – Mucor, Rhizopus, Aspergillus, Bipolaris, and Candida

14. Chronic Invasive Fungal Sinusitis – Clinical Features
Usually immunocompetent
History of chronic rhinosinusitis
Usually persistent and recurrent disease
Maxillofacial soft tissue swelling, orbital invasion with proptosis, cranial neuropathies, decreased vision, can invade cribiform plate causing headaches, seizures, decreased mental status

15. Chronic Invasive Fungal Sinusitis – Imaging
Noncontrast CT – Hyperattenuating soft tissue mass withing one or more of paranasal sinuses, bone involvement often gives mottled appearance with or without sclerosis
May mimic malignancy with masslike appearance and extension beyond sinus confines
MRI – decreased signal on T1, markedly decreased signal on T2 weighted images

16. Chronic Invasive Fungal Sinusitis

17. Chronic Invasive Fungal Sinusitis – Treatment
Surgical exenteneratin of affected tissues and systemic antifungal
Needs aggressive treatment

18. Chronic Granulomatous Invasive Fungal Sinusitis
AKA primary paranasal granuloma and indolent fungal sinusitis
Primarily found in Africa (Sudan) and Southeast Asia, only few case reports in US
Immunocompetent
Caused by Aspergillus flavus
Characterized by noncaseating granulomas in the tissues

19. Chronic Granulomatous Invasive Fungal Sinusitis
Chronic indolent course similar to chronic invasive fungal sinusitis
Considered by some as same entity as chronic invasive fungal sinusitis
Imaging characertistics are similar to those of chronic invasive fungal sinusitis
Often resembles a mass/neoplasms
Treatment is surgical debridement and systemic antifungals

20. Allergic Fungal Sinusitis
Most common form of fungal sinusitis
Common in warm, humid climates of Southern US
Hypersensitivity reaction to inhaled fungal organisms resulting in chronic noninfectious inflammatory reaction - IgE type I immediate hypersensitivity and type III hypersensitivity are involved
Common organisms implicated – Bipolaris, Curvularia, Alternaria, Aspergillus, and Fusarium
“Allergic mucin” within affected sinus which is inspissated mucous the consistency of peanut butter with eosinophils on histology

21. Allergic Fungal Sinusitis - Clinical
Younger individuals, third decade, immunocompetent
Often associated history of atopy with allergic rhinitis or asthma
Chronic headaches, nasal congestion, and chronic sinusitis for years

22. Allergic Fungal Sinusitis - Imaging
Usually bilateral with multiple sinuses involved if not pansinus involement
Often has a nasal component
Noncontrast CT – high attenuation allergic mucin within lumen of sinuses – can mimic a mucocele with expansion of the sinus
MRI – variable T1 appearance, low T2 signal (attributed to high concentration of iron, magnesium, and manganese concentrated by fungal organisms and also due to a high protein, low free water content of allergic mucin

23. Allergic Fungal Sinusitis - Imaging

24. Allergic Fungal Sinusitis - Imaging
Moderately high T1 signal, low T2 signal with expanded sinus can be seen in allergic fungal sinusitis, mucocele, or sinonasal polyposis

25. Allergic Fungal Sinusitis - Treatment
Surgical removal of allergic mucin with restoration of normal sinus drainage is goal
Longterm use of topical nasal steroids helps suppress the immune response and minimize recurrence
Topical or systemic antifungals are not indicated

26. Fungus Ball Older individuals, female>male Immunocompetent
Asymptomatic or minimal symptoms with chronic pressure or nasal discharge
Cacosmia (perception of foul odor when no such odor exists)

27. Fungus Ball
Mass within the lumen of paranasal sinus and is usually limited to one sinus
Frontal sinus most common followed by sphenoid sinus
Noncontrast CT – hyperattenuating mass often with punctate calcifications
MRI – variable T1 and hypointense T2 due to absence of free water, calcifications and paramagnetic metals also generate decreased T2 signal – no central enhancement to differentiate from neoplasm

28. Fungus Ball - CT
High density material with thickened walls of the maxillary sinus due to chronic inflammation

29. Fungus Ball Treatment
Surgical Removal with restoration of drainage of the sinus
Antifungal medications usually unnecessary
Recurrence is rare