Do you know the imaging manifestations of cerebral aspergillosis?

Aspergillus is a common fungus in the environment
.

Humans are usually infected by inhalation of spores, which are the most common cause in immunocompetent patients and can lead to localized infections in the lungs, sinuses, or other sites
.

In immunocompromised subjects, it can lead to life-threatening invasive infections; this is very rare in immunocompetent patients
.

Today we share a rare case of cerebral aspergillosis and its imaging findings in an immunocompetent patient
.

 Compiled and organized by Yimaitong, please do not reprint without authorization
.

 Case profile A previously healthy 6-year-old girl was admitted to the emergency room after experiencing an isolated tic crisis
.

The patient was diagnosed with febrile seizures and viral infection, for which supportive care was instituted
.

One week later, the patient developed progressive right-sided hemiparesis and underwent non-contrast CT (Figure 1), which was reported as a right frontal lobe tumor; the patient was subsequently transferred for further workup and brain MRI
.

 Figure 1.
Axial non-enhanced CT of the basal brain shows extensive vasogenic edema in the right frontal lobe with scattered hemorrhagic areas, with minimal mass effect
.

Source: Department of Radiology, High Specialty Regional Hospital of elBajio, Mexico, 2019 Imaging findings: Brain magnetic resonance imaging (Figure 2) shows an irregularly shaped right frontal lobe lesion with blurred margins, peripheral vasogenic edema, and some Area of ​​hemorrhage; despite the size of the lesion and extensive vasogenic edema, the mass effect was mild
.

In contrast-enhanced scans, there is an "open ring" enhancement
.

No diffusion limit found
.

Other smaller lesions with similar features were found
.

Imaging of the head and neck showed no signs of an infectious process
.

Biopsy revealed a granulomatous inflammatory process with vasodilation
.

The patient was started on steroids and supportive measures
.

 Figure 2a Axial T1-weighted image of the basal brain shows irregular and heterogeneous lesions in the right frontal lobe with indistinct borders and high-intensity foci in the frontal lobe suggestive of hemorrhage Figure 2b Axial FLAIR-weighted image of the basal brain shows extensive right frontal lobe angioedema , with minimal mass effect Figure 2c Sensitivity-enhanced image of the basal axis of the brain showing multiple lesions in the right frontal lobe, representing microbleeds Figure 2d Axial diffusion-weighted image of the skull base shows a clear area of ​​large hyperintensity in the right frontal lobe Figure 2e The basal axis of the brain The ADC map showed extensive hyperintensity consistent with DWI, with well-defined boundaries.
Figure 2f Axial gadolinium-enhanced t1-weighted image of the skull base showed irregular "open-loop" enhancement in the right frontal lobe
.

Other similar sources of smaller satellite lesions exist: Department of Radiology, High Specialty Regional Hospital of elBajio, Mexico, 2019 No improvement was achieved with the given treatment, so a second MRI was performed (Figure 3), Shows an increase in the number and size of lesions
.

 Figure 3a Axial FLAIR image of the brain shows extensive vasogenic edema in the right frontal lobe with increased mass effect Figure 3b Axial gadolinium-enhanced T1-weighted image of the brain at follow-up shows biopsy-induced surgical changes and increased size of satellite lesions Figure 3c Follow-up axis Gadolinium-enhanced T1-weighted image showed a new large right parietal lesion with open ring enhancement
.

Source: Department of Radiology, High Specialty Regional Hospital of elBajio, Mexico, 2019 Case discussion Aspergillus is a common fungus in the environment
.

Humans are usually infected by inhalation of spores, which are the most common cause in immunocompetent patients and can lead to localized infections in the lungs, sinuses, or other sites
.

In immunocompromised subjects, it can lead to life-threatening invasive infections; this is very rare in immunocompetent patients
.

CNS aspergillosis is becoming more common due to the increased prevalence of immunosuppression and the increased life expectancy of these patients
.

 When Aspergillus infects the central nervous system, it usually reaches the central nervous system by blood transmission; direct inoculation may come from the paranasal sinuses or trauma (including surgery)
.

The prognosis for cerebral aspergillosis is poor, especially since its diagnosis usually occurs later in the disease
.

The reported mortality rate was 88%
.

Diagnosis may be delayed
.

Since symptoms are nonspecific, especially in immunocompetent patients, this CNS infection is rarely suspected
.

 The clinical presentation of cerebral aspergillosis is nonspecific; it may include changes in mental status, behavioral changes, hemiparesis, dysarthria, somnolence, and seizures
.

Although the disease is contagious, it may or may not be febrile
.

These signs and symptoms of immunosuppressed patients require neuroradiological evaluation
.

Immunocompetent patients may have fewer specific signs and symptoms; moreover, invasive fungal infections are not considered part of the identification of these patients
.

 Imaging plays an important role in the management of these cases, but the features found are not always conclusive
.

Cerebral aspergillosis manifests primarily as hemorrhagic infarcts (due to Aspergillus invading blood vessels) and abscesses; however, encephalitis, meningitis, and fungal aneurysms may also occur
.

Most common imaging findings are lobulated abscess with thick-walled enhancement (host defense), severe inflammation involving adjacent structures (paranasal sinuses, dura mater with focal meningitis, osteomyelitis), and extensive parenchymal edema; more than half of patients had corpus callosum lesions (affected only in a few diseases), a sign that can help narrow the differential diagnosis
.

In cases of Aspergillus abscesses, DWI/ADC target lesions are common
.

This can be explained by central necrosis and outer hyphal margins with peripheral inflammation
.

 Conclusion Cerebral aspergillosis is a rare but often fatal complication of invasive aspergillosis
.

Unclear symptoms and signs complicate the management of these patients, and a lack of suspicion may delay diagnosis and treatment
.

 Common differential diagnoses: high-grade glioma, acute disseminated encephalomyelitis, bacterial abscess
.

 Imaging plays an important role in disease diagnosis; therefore, radiologists should use it as a differentiator between immunocompetent and immunocompromised patients in order to initiate appropriate antifungal therapy as early as possible
.

 Cerebrospinal fluid was determined to be Aspergillus encephalitis, and PCR was positive for Aspergillus
.

Antifungal therapy was initiated with a positive clinical and radiological response
.

 Yimaitong compiled from: https://