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.