Parapharyngeal lesions
Post Styloid
Pre Styloid
Deep lobe parotid tumors (45%) (look for fat plane)
Schwannoma : most common post styloid mass
Paraganglioma: second most common neurogenic PPS tumor: from nodose ganglion of vagus, carotid body (most common - 65%), jug bulb
Pleomorphic adenoma
Neurogenic tumors (35%)
Schwannoma: Most common neurogenic tumor
Paraganglioma
Neurofibroma: 3rd most common neurogenic tumor of PPS - schwann cells and peerineural fibroblasta.
Lymphoma
Vascular
LN
Meningioma
Hemangioma
Chondrosarcoma
Lymphoma
MEC most common malignant
Vagus > sympathetic chain
Familial paraganglioma: younger age and multiple sites. MEN 2- VHL, NF1. Genetic defect Is SDHA/B/C.
should do CT , MRI, 24 hr urs collection of vanillymandelic acid and metanephrines, serum catecholamines
Histology: Chief cells - granule storing (unaffected by radiotherapy), sustentacular cells - schwann-like cells, zelballen pattern, chief cell clusters enclosed In fibrous septa
Most common benign neoplasm of the temporal bone - females, left, 5th decade. Carotid body, tympanic, jugular
5% malignant, 3% active secretors
CT shows Irregular destruction of jug foramen and temp bone - MRI shows salt and pepper mix on T1 and T2
Vessels feeding: Ascending pharyngeal, post auricular, occipital, IMAX, Ipsilateral or contralateral ICA.
Glomus tympanicum: type of paraganglioma - arise In the middle ear, part of ear between eardrum and Inner ear structures
Glomus jugulare: cluster of paraganglion cells near the jugular foramen In base of skull.
CPA lesions
Vestibular schwannoma (acoustic neuroma) - 80% most common adult lesion
Meningioma (5%)
Epidermoid (3%)
Paraganglioma
Hemangioma
Uncommon: Metastatic, lipoma, dermoid, teratoma, chordoma, chondrosarcoma, giant cell tumor
Petrous apex lesions
Cholesterol granuloma (more frequent than epidermoid In petrous apex)
Epidermoid
Mucocele
Petrous apcitis / osteomyelitis
Meningioma
Glomus tumours (tympanicum, jugulare)
Chondrosarcoma
Lymphoma/mets
MRI findings of CPA/Petrous apex tumors
T1
T2
Iso/hypointense
Iso/hyperintense
GAD
Very strong
Vest schwannoma
Vest schwannoma
Vest schwannoma
Meningioma
Variable
Meningioma
Strong
Meningioma
Epidermoid (cholesteatoma)
Hyperintense (like CSF)
Epidermoid (cholesteatoma)
Non enhancing
Epidermoid (cholesteatoma)
Flair:
Isointense
Epidermoid (cholesteatoma)
DWI:
Hyperintense
Epidermoid (cholesteatoma)
Hypointense
Arachnoid cyst
Arachnoid cyst
Arachnoid cyst
Hypointense
Arachnoid cyst
Hypointense
Arachnoid cyst
Paraganglioma (S&P)
Paraganglioma (S&P)
Paraganglioma
Cholesterol granuloma (only lesion that does both other than endolymphatic sac tumor)
Cholesterol granuloma
Hyperintense
Cholesterol granuloma (only lesion that does both)
Dermoid
Hypointense
Dermoid
Dermoid
Chordoma / Chondrosarcoma
Chordoma / Chondrosarcoma
Chordoma / Chondrosarcoma
Petrous apicitis
petrous apicitis
Rim enhancement
Petrous apicitis
Endolymphatic sac tumor
Endolymphatic sac tumor
Mucocele
Mucocele
Lipoma
CT: Isodense to brain, calficiations, central necrosis
MRI: T1 - Isoitense to brain, Hyperintense to CSF, T2: hyperintense to brain, hypointense to CSF, GAD Intense enhancement
Acute angle on temp bone, homogenous enhacement, no dural tail, rare calcifications, elnarged IAC, never dumbell,
CT: Isodense to brain, may see calcifications
MRI: t1 -isointense to brain, T2: hyperintense to brain, hypointense to CSF, GAD enhacement
Sessile, broad base, obtuse angle to petrous bone, eccentric over IAC, have dural tail, calficiations
CT: Hypodense to CSF, T1 - hypointense to brain, Isointense to CSF, T2 hyperintense to brain, FLAIR Intermediate
May dumbbell (classic dumbbell) Into MCF or contralateral cistern cauliflower surface appearance.
Inferior vestibular nerve
Histopathology: Alternating regions of compact spindle cells (antoni A and loose hypocellular areas (antoni B) - nuclei are spindled and palisade forming verocay bodies - whorled or palisading appearnce of antoni A cells
Management: Observation , surgery, radiation therapy (stereotactic- gamma knife, fractioned sterotactic, proton beam therapy)
Cap cells from tips of arachnoid villi: Lobulated cells - psommoma bodies present.
1% of Intracranial tumors - 3% of cpa lesions. Entrapped epithelial rests.
Most common!
Pathogenesis: Obstruction vacuum theory: obstruction of air cell drainage pathways - Inflammation and hemorrhage, breakdown of RBCs and foreign body reactions. Exposed marrow theory: bone marrow next to mucosa causes hemorrhage and breakdown
Rare, agressive papillary tumors - 50% associated with VHL - , histology shows proteinaceous material similar to thyroglobulin.
Chordoma: Rare, slow growing malingnacy from notochord remnant. Histology: Physaliferous cells (soup bubble appearance) - sphenoocciptal, vertral or sacrococcygeal types. Classic, chondroid or atypical types.