Case of the week Details

A. LEGENDS:

• Opacification in bilateral frontal and ethmoid sinus showing enhancement on post contrast images.
• The mucosal thickening seen extending along the craniectomy defect with adjacent dural thickening.
• Cystic encephalomalacic changes seen in the anterior part of left frontal lobe.

B. LEGENDS:

• Mucosal thickening in left frontal sinus with hyperdense content, suggestive of fungal elements/ inspissated secretions.
• Hyperdense soft tissue component is seen extending into anterior and middle cranial fossa and into extraconal compartment of left orbit with mild displacement of superior oblique and superior rectus muscle. 
• Bony erosion of superior and medial wall of left orbit and floor of anterior cranial fossa

C. LEGENDS:

• Well-defined T2/ FLAIR hypointense, T1 isointense extra-axial, broad based lesion in left frontal and temporal regions along lesser wing of sphenoid with surrounding vasogenic edema noted.
• No diffusion restriction.
• No blooming on GRE images.

D. LEGENDS:

• On post contrast the lesion shows homogeneous enhancement with impression of a dural tail laterally.
• Medially the lesion abuts the left cavernous sinus and encases the cavernous segment of left ICA.
• MR spectroscopy shows choline peak.

Intracranial Fungal granuloma

TREATMENT

• Endonasal clearance of PNS with left frontotemporal craniotomy and tumor excision. 
• On the 3rd post operative day, the patient had one episode of seizure with altered sensorium.

DIAGNOSIS

Angio-invasive intracranial aspergillosis with left PCA pseudoaneurysm, SAH and left SCA territory infarct

TREATMENT

Flow diverter deployment and partial coiling of left P1 PCA aneurysm

DISCUSSION:

• Fungal infections can spread by inhalation, ingestion, or direct contact such as trauma
• MC - Zygomycetes class (Rhizopus, Mucorale, and Rhizomucor species) and Aspergillus 
• Risk factors - poorly controlled diabetes, haematologic malignancies, organ transplant, immunosuppressive agents, and immunosuppressive diseases 

Pathophysiology

• Fungal infection makes phagocytes dysfunctional and can adhere to endothelial cells causing endothelial damage. 
• They manipulate their environment while acquiring iron from the patient, which is essential for their growth and replication 
• Neutrophils helps in destruction of the hyphae and the prevention of germination. In neutropenic pts, high chances of getting fungal infection.

C/F

• Facial swelling and pain, headache.
• Fever
• Nasal congestion 
• Proptosis, 
• Cranial nerve palsy 

MC anatomic locations - Nasal cavities (middle turbinates),  maxillary sinuses. 
A definitive diagnosis of fungal rhinosinusitis is made on the basis of tissue biopsy.

Cavernous Sinus Extension

Symptom:

• headache  visual impairment, ophthalmoplegia thrombosis and narrowing of the internal carotid artery Direct findings
• Enlargement and expansion of the cavernous sinus with bulging lateral walls 
• Loss of flow voids, with restricted diffusion suggests cavernous sinus thrombosis
• Bone destruction.

Indirect findings 

• Narrowing of ICA flow void
• Dilatation and/or subsequent thrombosis of the superior and inferior ophthalmic veins 

Large- and Small-Vessel Involvement

Symptoms - vision change, ptosis or cranial nerve palsy, headache 

Imaging findings

• Because of the decreased resistance to intra-arterial pressure caused by the destruction fungal aneurysms tend to be fusiform, with a longer shape and a more proximally localized 
• Tendency of fungi to invade proximal arteries leads to a larger infarction. 
• Thickening and enhancement of the ICA wall with or without narrowing indicate ICA involvement
• Vascular involvement - smooth or nodular wall enhancement 
• Thrombus -  absence of contrast enhancement, diffusion restriction,  loss of flow voids

Direct Intracranial Extension and Intracranial Dissemination

• Many fungi penetrate BBB by transcellular (transendothelial cells) migration, degradation of the tight junctions or crossing the endothelial cell layer in phagocytes 
• Cerebritis, infarction, hemorrhage, meningitis, abscess, subdural empyema, thrombosis of dural sinuses, and arterial involvement.
• Perineural invasion (most commonly along trigeminal nerve)
• Involvement of the ipsilateral pterygopalatine fossa in sinusitis, without bone destruction, indicates perineural or perivascular spread along the sphenopalatine artery. 

REFERENCE

Deadly fungi: Invasive fungal rhinosinusitis in the head and neck
Mariko Kurokawa, Ryo Kurokawa, Akira Baba, John Kim, Christopher Tournade, Jonathan Mchugh, Jonathan D.Trobe, Ashok Srinivasan, Jayapalli Rajiv Bapuraj, Toshio Moritani
https://doi.org/10.1148/rg.220059

Dr ANITA NAGADI
Senior Consultant Radiologist 
Manipal Hospital, Yeshwanthpur, Bengaluru.

Dr SHIKHA JOSHI
Radiology resident
Manipal Hospital, Yeshwanthpur, Bengaluru.