acute invasive fungal sinusitis

Acute invasive fungal sinusitis is the most aggressive form of fungal sinusitis. It is seen particularly in immunocompromised patients and is the source of significant morbidity and mortality. It should be distinguished from the other two forms of invasive fungal sinusitis, chronic invasive fungal sinusitis, and chronic granulomatous invasive sinusitis, which are discussed separately.


Acute invasive fungal sinusitis is seen in immunocompromised patients, hence the demographics will match those of the underlying immunosuppressing condition. Common causes of underlying immunosuppression include :

  • diabetes mellitus: especially those with ketoacidosis
  • neutropenia
    • hematologic malignancies
    • solid organ transplants
    • bone marrow transplantation
    • chemotherapy-induced neutropenia
  • advanced AIDS

Clinical presentation

Clinical presentation is variable but often dramatic, with rapid development of fever, facial pain, nasal congestion, epistaxis and sensation loss in the malar areas. Extension into the orbit, cavernous sinus, or intracranial compartment is frequent, resulting in deterioration in vision, proptosis, and neurological deficits, respectively .

The disease progresses over a few days or at most a few weeks and often results in vascular invasion and systemic dissemination .


Infection is believed to originate in the nasal cavity (most often the middle turbinate) with subsequent spread to the paranasal sinuses . Several fungal agents are implicated, including :

  • Aspergillus spp: typically in neutropenic patients
  • Zygomycetes: usually in diabetic patients
    • Rhizopus spp
    • Mucor spp
    • Rhizomucor spp
    • Absidia spp

The infection can spread rapidly from the sinuses via vascular invasion and bony erosion, potentially leading to an extension to the orbit, brain, cavernous sinus or carotid arteries .

Radiographic features


Unlike chronic invasive fungal sinusitis, acute infection generally does not demonstrate hyperdense material within the sinus on non-contrast CT. CT is particularly effective at assessing bony changes. Findings include :

  • mucosal thickening: hypoattenuating
  • opacification of the sinus: soft tissue attenuation
  • bone destruction: may be extensive or very subtle or even inapparent (extension through intact bone via vascular invasion)
  • nasal septal ulceration
  • fat stranding outside the sinus perimeter
    • intraorbital fat
    • periantral fat
    • nasolacrimal duct
    • lacrimal sac
    • masticator space
    • pterygopalatine fossa

Imaging findings may be mild, particularly in the early phases of the disease. The degree of sinonasal mucosal thickening may be mild and is not sensitive or specific for the diagnosis of the disease. Presence of any one of the above findings should raise suspicious of invasive fungal sinusitis in high-risk patients . Mild periantral fat stranding is often the first sign of vascular invasion and spread beyond the paranasal sinuses.

Features of potential complications should also be sought (see below).


MRI is the modality of choice to assess soft tissue extension. The findings within the sinus itself are variable, and range from mucosal thickening, to complete opacification of the sinus.

  • T1: intermediate low signal
  • T2
    • fungal mass is of intermediate to low signal
    • often associated with fluid or blood elsewhere in the paranasal sinuses
  • T1 C+ (Gd): absent sinus mucosal enhancement suggests necrosis; invasion outside the sinus appears as an increased enhancement

Particular attention should be paid to the assessment of invasion beyond the sinuses. In some cases, a complication may be obvious (see below). The early invasion should be sought, and findings that are particularly important include :

  • stranding of the periantral fat (T1 and STIR/T2 fat-sat)
    • intraorbital fat
    • masticator space
    • pterygopalatine fossa
  • subtle enhancement (T1 C+ fat-sat)
  • leptomeningeal enhancement
  • intracranial granulomas: low signal on both T1 and T2
  • cavernous sinus thrombosis 
  • carotid pseudoaneurysm 
  • cerebritis
  • brain abscess 

Treatment and prognosis

The key to successful management is early and aggressive medical and surgical treatment and correction of neutropenia. Systemic antifungal (e.g. amphotericin B) should be administered and diabetic ketoacidosis or neutropenia should be corrected.

Aggressive surgical débridement is usually required.

Complications include :

Despite modern management, mortality remains high (50-80%), especially in patients whose neutropenia cannot be corrected, and in general is higher in diabetic patients (often due to later presentation) . Reduced mortality, down to as low as 18%, has been reported in at-risk patients under close active surveillance .

Differential diagnosis

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