Fungal Sinusitis: An Overview

Cade Martin, MD

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

Fungal Sinusitis

• Invasive– 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

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)

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

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

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

Acute Invasive Fungal Sinusitis - CT

• Unilateral ethmoid involvement with bone destruction, intraorbital spread and proptosis

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.

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

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

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

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

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

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

Chronic Invasive Fungal Sinusitis

Chronic Invasive Fungal Sinusitis – Treatment

• Surgical exenteneratin of affected tissues and systemic antifungal

• Needs aggressive treatment

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

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

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

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

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

Allergic Fungal Sinusitis - Imaging

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

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

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)

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

Fungus Ball - CT

• High density material with thickened walls of the maxillary sinus due to chronic inflammation

Fungus Ball Treatment

• Surgical Removal with restoration of drainage of the sinus

• Antifungal medications usually unnecessary

• Recurrence is rare