DEFINITION Skull Base Tumors Tumors arising from the tissues of the skull base Any mass that involves (or abuts) the base of skull

Primary bone and cartilage lesions may not always be distinguished from those originating above (intracranial) Zoran Rumboldt or below (neck, paranasal sinuses, orbits) Other conditions can mimic neoplasms University of Rijeka Medical University of South Carolina Lesions that can occur anywhere in the skull base Telemedicine Clinic MarinMed Clinic Lesions that are typical for a certain region

Anterior Fossa (frontal sinuses to sphenoidal ridge & planum sphenoidale) - sinonasal and orbital masses - intracranial lesions

Middle Fossa (sphenoidal ridge to petrous ridge) :

Central Skull Base - chordoma & chondrosarcoma - sella & perisellar masses - nasopharyngeal & sinonasal lesions

Lateral / Temporal - petromastoid (ear mass lesions)

Posterior Fossa (behind petrous ridge and clivus)

Paraganglioma (Osseous) Meningioma Location / Origin of a Lesion Skull Base (Intraosseous) Epidermoid Anatomy Nerve Sheath Tumors Ecchordosis Physaliphora Specific Imaging Findings Cavernous Sinus Hemangioma Pituitary Adenoma Clival Canal Craniopharyngioma Skull Base Defects Mucoceles Osteolytic & Enhancement Juvenile Nasopharyngeal Angiofibroma Lesion Margins Langerhans Cell Histiocytosis Allergic Fungal Sinusitis Complications of Infections Osteoblastic Patterns Giant Cell Tumor Density/Intensity Cholesterol Granuloma Patterns DWI - ADC ICA Aneurysm Chordoma Fibrous Dysplasia Chondrosarcoma Osteochondroma Sinonasal Tumors Osteoma Patient’s Age Nasopharyngeal Tumors Paget’s Plasmacytoma/MM Osteonecrosis Juvenile Nasopharyngeal Angiofibroma Rhabdomyosarcoma Paget’s Endolymphatic Sac Tumor and many more… Metastatic Neuroblastoma Plasmacytoma Perineural Tumor Spread Metastatic Neoplasms Lymphoma The extent of the lesion & its relationship to vital structures Neurosurgery 2018; 82: 255 IMAGING TECHNIQUE

CT BONE window and ALGORITHM/FILTER CT bone filter & window T1w no FS thinnest possible slices (detector width) SOFT TISSUE window and algorithm thicker (3mm) slices, post contrast

MRI T1-weighted images WITHOUT FAT SATURATION T2-weighted STIR T1w T2w T1w Post contrast T1-weighted w/o & with fat saturation Gd Pol J Radiol 2017; 82: 398 no FS

T1w FLAIR T1w Gd

Anterior Cranial Fossa

- sinonasal and orbital masses - intracranial lesions

T1w Gd T2w

T1w FLAIR T1w Gd Olfactory Neuroblastoma T1w T1w Gd Olfactory Meningioma

T2w

Centered at cribriform plate T1w Intracranial cystic areas Gd T2w T2w Ethmoid Allergic Fungal Sinusitis Mucocele

FLAIR

T1w

Completely opacified T1w NECT and expanded sinus (cell) Gd

AFS

Middle Cranial Fossa

Central Skull Base

- chordoma & chondrosarcoma - sella & perisellar masses (BL) Expanded Sinuses - nasopharyngeal & sinonasal lesions with Hyperdense Stuff Images/Symptoms Mismatch Teenagers

through sellar floor filling sphenoid sinus NPC

Pituitary from nasopharynx - marrow infiltration, then destruction Adenoma

T1w Gd T1w T1w Gd T2w Encephalocele from Clivus Osteolytic T2w Hypodense Mass

Chordoma

protruding into Skull Base Defect Brainstem with CSF/Brain Very high T2 T1w

T1w from petroclival junction T2w Chordoma (synchodrosis – cartilage) Whirls of calcs (in 50%)

Chondrosarcoma ADC Typical stippled Very high ADC enhancement (unless high grade) Very High ADC Variable (minimal) T2w enhancement T1w Gd ADC T1w Gd

Chondrosarcoma Chordoma T2w

NECT may be off midline and not differentiated T1w Gd from Chondrosarcoma Ecchordosis Ecchordosis Physaliphora Physaliphora

T2w

AJNR 2004; 25:1851

T1w Gd

Plasmacytoma T1w T2w

(Inferior Median) Clival Canal

Oval with sharp margins Both EP & CC - thought to be remnants of notochord Clivus & Petroclival T1w FS Gd

T2w T1w Sellar Meningioma

Fibrous Dysplasia T1w Gd Ground glass (+ cystic/lytic) with preserved cortical bone T2w MRI may be confusing – variable signal/enhancement

T2 iso to hypointense dural T1w Gd , “ tail”, narrows ICA Hemangioma of the Cavernous Sinus

T1w T2w T1w Gd Middle Cranial Fossa

Lateral / Temporal

- petromastoid (ear mass lesions) ADC very bright on T2WI & ADC, avidly enhances

Schwannoma Rhabdomyosarcoma Trigeminal - V3 Foramen Ovale T1w T1w Gd

T2w

Foramen Ovale into the Masticator Space Masticator Space not from bone kids-young adults

T2w T1w Meningioma Gd Fibrous Dysplasia

Intra Extra & Cranial T1w Intraosseous Fibrous Meningioma Dysplasia Reactive cortical bone changes Densely enhancing T1w extraosseous portion T2w Gd

No extraosseous enhancing mass

Ground glass Preserved cortex T1w T1w Gd CECT

4yo girl with a rapidly enlarging mass

T1w Gd T2w

ADC Metastatic Neuroblastoma Langerhans Cell Histiocytosis Osteosarc - like Scan the belly Low Diffusion Temporal/Orbit Young Child T1w FS Gd Glomus Jugulare Glomus Jugulare

T2w T1w Gd

3D TOF

Enhancing Mass with Flow voids at Jugular Foramen Infiltrative Osteolysis T2w T1w Gd

Jugular Schwannoma

Smooth bone remodeling ADC High ADC & T2 Avid enhancement No flow voids Location - Direction! T2w CN VII Schwannoma

Location! along CN VII Facial Ganglion nerve T1w T1w FS Gd

Endolymphatic Sac Tumor Retrocochlear Infiltrative High Osteolytic mass T1 & T2

T2w T1w

centered at T1w Endolymphatic Gd duct/sac VHL ? Cholesterol Granuloma T1w T2w Cholesterol Granuloma

Smooth sharp petrous apex expansion T1 & T2 hyper T2* T1w Gd T1w T2* T2w

Coalescent Mastoiditis

Coalescent Mastoiditis T1w Gd

Destruction of Mastoid Septae

Anterior Fossa (frontal sinuses to sphenoidal ridge & planum sphenoidale) Lymphoma - sinonasal and orbital masses - intracranial lesions T2w Middle Fossa (sphenoidal ridge to petrous ridge) : Bone Not T2 bright Central Skull Base - chordoma & chondrosarcoma Infiltration - sella & perisellar masses Homogenous without - nasopharyngeal & sinonasal lesions enhancement destruction Lateral / Temporal - petromastoid (ear mass lesions) Low diffusion ADC dark Posterior Cranial Fossa

T1w Insights Imaging 2018; 9: 84 T1w Gd Posterior Condylar Canal Epidermoid (Cholesteatoma)

T2w DWI

Occipital emissary vein

CSF-like on CT, T1w & T2w DWI bright

Epidermoid Arachnoid Granulations T2w

Along sinuses Lobulated bone remodeling Not always T2 bright

DWI

Hemangioma Chordoma Chondrosarcoma Glomus Jugulare Sinonasal Tumors Venous Malformation Endolymphatic Sac Tumor Nasopharyngeal Tumors Intraosseous Meningioma Rhabdomyosarcoma Cavernous Sinus Hemangioma Lymphoma Intraosseous Epidermoid Plasmacytoma Metastatic Neuroblastoma Ecchordosis Physaliphora Perineural Tumor Spread Skull Base Defects Fibrous Dysplasia Mucoceles Cholesterol Granuloma Allergic Fungal Sinusitis Location / Origin of a Lesion Know Your Skull Base Anatomy Specific Imaging Findings

Osteolytic & Enhancement Osteoblastic Margins Patterns Patterns Density/Intensity DWI - ADC

Patient’s Age

The extent of the lesion & its relationship to vital structures