Imaging of facial nerve schwannomas: diagnostic pearls and potential pitfalls

Schwannomas are uncommon in the facial nerve and account for less than 1% of tumors of temporal bone. They can involve one or more than one segment of the facial nerve. The clinical presentations and the imaging appearances of facial nerve schwannomas are influenced by the topographical anatomy of the facial nerve and vary according to the segment(s) they involve. This pictorial essay illustrates the imaging features of facial nerve schwannomas according to their various anatomical locations and also reviews the pertinent differential diagnoses and potential diagnostic pitfalls

Natalizumab-related progressive multifocal leukoencephalopathy-immune reconstitution inflammatory syndrome: a case report highlighting clinical and mrI features

Multiple sclerosis (MS) patients treated with natalizumab often face the uncommon but severe complication of developing progressive multifocal leukoencephalopathy (PML). PML may be further complicated by immune reconstitution inflammatory syndrome (IRIS) after the removal of the drug. Since both PML and IRIS are associated with high morbidity and mortality rates, early clinical and radiological diagnosis of these complications is of paramount importance. Here, we report a case of an adult male patient who was diagnosed with PML after receiving natalizumab therapy for 6 years for the treatment of MS. Upon cessation of natalizumab, he presented with a paradoxical worsening of clinical and radiological findings consistent with an inflammatory brain injury due to IRIS. He was treated with high dose corticosteroid therapy followed by a gradual improvement in clinical and imaging findings. This article illustrates the magnetic resonance imaging (MRI) features of natalizumab-associated PML-IRIS, along with a brief overview of its clinical features, complications and management strategies

Balo's concentric sclerosis with acute presentation and co-existing multiple sclerosis-typical lesions on MRI

Balo's disease also known as Balo's concentric sclerosis (BCS) is a rare demyelinating disorder which is characterized pathologically and radiologically by concentric rings of demyelinated and relatively myelin-preserved white matter. We describe the case of a 25-year-old female presenting with stroke-like symptoms who was diagnosed with BCS on MRI. At clinical onset, she also showed co-existing multiple sclerosis (MS)-typical lesions in the brain. This report extends the recent concept that BCS may share similar pathogenesis and radiological progression as MS lesions, that they may occur simultaneously in the same patient and that they may represent different manifestations of the same disease process. Also, BCS needs not be a fulminant disease and may often show a benign self-limiting course as in our case

Imaging of adult brainstem gliomas

Brainstem gliomas (BSGs) are uncommon in adults accounting for about 2% of all intracranial neoplasms. They are often phenotypically low-grade as compared to their more common paediatric counterparts. Since brainstem biopsies are rarely performed, these tumours are commonly classified according to their MR imaging characteristics into 4 subgroups (a) diffuse intrinsic low-grade gliomas, (b) enhancing malignant gliomas, (c) focal tectal gliomas and (d) exophytic gliomas/other subtypes. The prognosis and treatment is variable for the different types and is almost similar to adult supratentorial gliomas. Radiotherapy (RT) with adjuvant chemotherapy is the standard treatment of diffuse low-grade and malignant BSGs, whereas, surgical resection is limited to the exophytic subtypes. Review of previous literature shows that the detailed imaging of adult BSGs has not received significant attention. This review illustrates in detail the imaging features of adult BSGs using conventional and advanced MR techniques like diffusion weighted imaging (DWI), diffusion tensor imaging (DTI), MR perfusion weighted imaging (PWI), MR spectroscopy (MRS), as well as 18 F-fluoro-ethyl-tyrosine positron emission tomography (18F-FET/PET). We have discussed the pertinent differences between childhood and adult BSGs, imaging mimics, prognostic factors and briefly reviewed the treatment options of these tumours

A case report on 1-year follow-up of bilateral thalamic glioma

Bilateral thalamic glioma is one of the rarest tumor occurrences, representing a small fraction of thalamic gliomas, which only accounts for 1-1.5% of all brain tumors. It is usually a diffuse, low-grade astrocytoma (WHO grade II), seen mainly in adults, with approximately 25% of them involving children under the age of 15. Radiotherapy is the main mode of treatment since surgical intervention is limited to a role of biopsy and management of secondary effects, due to the deep brain location of the lesion and the complexity of the involved structures. We report a 1-year follow-up of a 55-year-old female patient with bilateral WHO grade II thalamic astrocytoma. Following histological and neuroradiological consensus regarding the diagnosis, the patient was referred for radiotherapy. The effectiveness of available therapy and long-term neuroradiological follow-up is not reliably established due to rapid fatal evolution following diagnosis. Contrary to the norm, our patient showed stable disease with radiotherapy for a 1-year period

Dedifferentiated laryngeal chondrosarcoma: combined morphologic and functional imaging with positron-emission tomography/magnetic resonance imaging

Chondrosarcoma of the larynx is a rare, low-grade malignancy in terms of histology and clinical behavior. We present an unusual case of laryngeal chondrosarcoma, which developed a large dedifferentiated component on recurrence after primary surgery. The diagnosis of dedifferentiation was suggested in view of the morphological and metabolic findings on hybrid positron-emission tomography/magnetic resonance imaging (PET/MRI) and was subsequently confirmed surgically. Whole-organ, slice-by-slice radiologic-histologic correlation revealed excellent delineation of the well-differentiated and dedifferentiated tumor components with PET/MRI. PET/MRI can provide additional functional information to supplement the morphological mapping and histopathology of these tumors

The pterygopalatine fossa: imaging anatomy, communications, and pathology revisited

The pterygopalatine fossa (PPF) is a small, clinically inaccessible, fat-filled space located in the deep face that serves as a major neurovascular crossroad between the oral cavity, nasal cavity, nasopharynx, orbit, masticator space, and the middle cranial fossa. Due to its inherent complex location and connections, it can potentially act as a natural conduit for the spread of inflammatory and neoplastic diseases across the various deep spaces in the head and neck. This review aims to acquaint the reader with the imaging anatomy of the PPF, its important communications, and to identify some major pathological conditions that can involve the PPF, especially in conditions where its involvement can have serious diagnostic and therapeutic implications, such as in perineural tumour spread

Aggressive primary olfactory neuroblastoma of the sphenoclival region: A case report and literature review

Olfactory neuroblastoma (ONB) is an uncommon malignant tumor of neural crest origin, which commonly arises in the superior nasal cavity. Ectopic origin of an ONB is exceedingly rare. We describe a rare case of an ectopic sphenoclival ONB with extensive involvement of the central skull base and with development of systemic metastases. To our knowledge, ours is the first case that describes the imaging features of this rare entity on computed tomography (CT), magnetic resonance imaging, 18 F-fluorodeoxyglucose-positron-emission tomography/CT, and digital subtraction angiography. We also describe the histological features, imaging differentials, and treatment options for this tumor along with a brief literature review

FDG-PET/CT pitfalls in oncological head and neck imaging

Positron emission tomography-computed tomography (PET/CT) with fluorine-18-fluorodeoxy-D-glucose (FDG) has evolved from a research modality to an invaluable tool in head and neck cancer imaging. However, interpretation of FDG PET/CT studies may be difficult due to the inherently complex anatomical landmarks, certain physiological variants and unusual patterns of high FDG uptake in the head and neck. The purpose of this article is to provide a comprehensive approach to key imaging features and interpretation pitfalls of FDG-PET/CT of the head and neck and how to avoid them