Week 4 - Cases 1-10

Case 1: What is the most likely diagnosis?

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DDx: Langerhans Cell Histiocytosis 1.

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Case 1: What is the most likely diagnosis?

Coalescent Mastoiditis Cholesteatoma Wegener’s Rhabdomyosarcoma Chondrosarcoma

Langerhans Cell Histiocytosis of Temporal Bone Langerhans cell histiocytosis (LCH) is rare granulomatous disease with proliferation of histiocytic cells usually occurring in children. A less severe form may occur in adults. Common locations with the head and neck include the lateral orbital wall and the temporal bone. Temporal bone involvement (15-60% of LCH cases) more typically involves the mastoid and EAC region, less likely the petrous apex. Patient’s can present with a draining ear and otalgia. Both MR and CT can be used to look for changes of LCH. Look for other central nervous system lesions, especially in the pituitary stalk. Typical findings are of an enhancing soft tissue mass with bone destruction (red arrows) including irregular margins. Treatment includes surgery, radiation, and/or chemotherapy.

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DDx

Case 2: What is the most likely diagnosis?

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Case 2: What is the most likely diagnosis?

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Case 2: What is the most likely diagnosis?

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Epidermoid of Petrous Apex

Case 2: What is the most likely diagnosis?

Epidermoids of the petrous apex are slow-growing lesions eroding into the internal auditory canal, facial nerve canal, otic capsule, and eventually the middle ear. Epidermoids contain keratin debris shed from a lining of squamous epithelium and solid cholesterin. The proportions of these two components determine the signal intensity on MRI. MRI findings often reveal a slightly inhomogeneous lesion, usually isointense or slightly hyperintense to CSF on T1- and hyperintense on T2-weighted images. Generally, no contrast enhancement occurs and they show restricted diffusion (red arrows). Epidermoids often have a variable configuration as they may conform to the shape of the space of origin.

DDx: Epidermoid of Petrous Apex 1.

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Chondrosarcoma Cholesterol Granuloma Primary Mucocele Schwannoma Meningioma

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DDx

Case 3: What is the most likely diagnosis?

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Case 3: What is the most likely diagnosis?

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Case 3: What is the most likely diagnosis?

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Lipoma of Internal Auditory Canal

Case 3: What is the most likely diagnosis?

Intracranial lipomas are nonenhancing lesions generally thought to be caused by the maldifferentiation of the primordial meninx primitiva, the loose embryonic mesenchymal precursor of the subarachnoid space and meninges. Direct incorporation of the meninx primitiva or its mesenchymal precursor into the developing otocyst as it invaginates, could explain the intracanalicular location of lipomas. Tumors in the internal auditory canal may infiltrate portions of the eighth cranial nerve. Signal intensity on fast spin echo T2-weighted images is variably hyperintense and suppressed with fat saturation (red arrows). Other than ipsilateral hearing loss, intracranial lipomas are generally asymptomatic. Because lipid materials or breakdown products could be transported via the membranous labyrinth to the cochlea, they then make a toxic effect on the cochlear hair cells, possibly explaining the frequency of hearing loss.

DDx: Lipoma of Internal Auditory Canal 1. Lipoblastic Meningioma 2. Vestibuloacoustic schwannoma 3. Hemanigioma

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DDx

Case 4: What is the most likely diagnosis?

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Case 4: What is the most likely diagnosis?

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Glomus Faciale

Case 4: What is the most likely diagnosis?

Glomus complex tumors are also called chemodectomas or paragangliomas are slow-growing lesions arising from nests of chemoreceptor tissue. The facial canal is a very uncommon location for glomus tumors to arise, and are usually non-functioning lesions of glandular tissue in this location. These tumors are benign, but almost always show an aggressive erosive pattern. Facial nerve glomus will show hyperintensity on T2-weighted images and will show marked enhancement on postcontrast T1-weighted MR (red arrows).

DDx: Glomus Faciale 1.

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Faciale Neuroma Congenital Cholesteatoma Hemangioma of Facial Nerve Perineural extension of Parotid Gland Tumor

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DDx

Case 5: What is the most likely diagnosis?

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Case 5: What is the most likely diagnosis?

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Glomus Jugulare

Case 5: What is the most likely diagnosis?

A glomus jugulare tumor is a paraganglioma that is confined to the jugular fossa. It is the most common of jugular fossa tumors. Glomus jugulare is seen most commonly in adults 40-60yo, with a moderate female predilection. Significant inner ear involvement produces pulsatile tinnitus and hearing loss and even some cranial nerve palsies (hoarseness, dysphagia). They are slow growing, encapsulated, invasive, and vascular lesions. CT demonstrates irregularly eroded bony margins centered around the jugular foramen (red arrows).

MR will show a soft tissue lesion with a “salt and pepper” appearance on T2 weighted images and marked enhancement post contrast. Malignant transformation is less common (2-13% of cases). Search for other paragangliomas should be performed. Schwannomas, by contrast, will show a smoothly marginated bony expansion of the jugular foramen and less prominent enhancement.

DDx: Glomus Jugulare 1.

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Jugular Schwannoma Bony Metastases Meningioma Jugular Bulb Thrombosis Normal Anatomic Variation (asymmetry of jugular bulb size, dehiscent jugular bulb)

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DDx

Case 6: What is the most likely diagnosis?

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Ossifying Hemangioma of Genticulate Ganglion

Case 6: What is the most likely diagnosis?

The ossifying type of hemangioma of the genticulate region describes a tumor that produces spicules of lamellar bone. These hemangiomas can cause symptoms both by nerve compression and invasion.

Presentation often includes cranial nerve VII paralysis of relatively rapid onset. On noncontrast CT, ossifying hemangiomas have a unique appearance as they invade bone, have ill-defined margins, and demonstrate a “honeycomb” appearance (red arrows). The stippled pattern of calcification is characteristic of an ossifying hemangioma. They are heterogeneously bright on T2-WI and enhance on both CT and MR. They grow eccentric to the facial nerve so the main lesion is seen anterior and superior to the facial canal. These are felt to occur as often as facial nerve schwannomas. They are benign. Other less common locations for benign vascular tumors of the temporal bone include the IAC and posterior genu.

DDx: Glomus Jugulare 1.

Normal Perivascular Enhancement

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Facial Nerve Schwannoma

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Viral Neuritis (Bell palsy)

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Metastasis

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DDx

Case 7: What is the most likely diagnosis?

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Endolymphatic Sac Tumor

Case 7: What is the most likely diagnosis?

Endolymphatic sac tumors are destructive, hypervascular papillary cystadenomatous tumors that originate from the retrolabyrinthine temporal bone, centered at the vestibular acqueduct operculum. They are associated with von Hippel-Lindau disease, but can be sporadic. In the former case they can be bilateral. These tumors are locally invasive. On T1-weighted MR images, heterongeneous signal is seen due to the presence of calcification/bony spicules, fluid, soft tissue, and hemorrhage. ELSTs show mostly hyperintensity on T2weighted images. Heterogenous enhacement is present. These lesions may spread to the cerebellum and the cerebellopontine cistern, and may mimic other more frequent tumors of this region. Additionally, ELSTs may erode the medial mastoid to involve the facial nerve, or transdurally to invade the posterior fossa.

DDx: Endolymphatic Sac Tumor 1.

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Glomus jugulare Choroid Plexus Papilloma Metastatic Tumors Meningioma Acoustic schwannoma

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DDx

Cholesteatoma of Temporal Bone (No Surgery)

Case 8: What is the most likely diagnosis?

Cholesteatoma can be acquired (98%) or congenital (2%). Acquired ones are erosive collections of keratinous debris from an ingrowth of stratified squamous debris. They are typically seen along the pars flaccida region of the TM extending into Prussak’s space. The hallmark of cholesteatoma is soft tissue mass with bony destruction. In advanced cases, there may be complete erosion of the ossicles, fistula of the horizontal semicircular canal, and wall erosion of the tympanic segment of the facial nerve canal. The contents of an acquired cholesteatoma may drain externally, leaving only the aggressive peripheral microscopic membrane that consists of keratinizing stratified squamous epithelium. This is what is referred to as an automastoidectomy. No soft tissue mass is seen in imaging and CT appearance is reminiscent of mastoidectomy.

DDx: Acquired Cholesteatoma 1.

Wegener’s

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Metastasis

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Coalescent mastoiditis

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Langerhans cell histiocytosis

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Rhabdomyosarcoma

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DDx

DDx: Prussak’s Space Cholesteatoma 1.

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Case 9: What is the most likely diagnosis?

Cholesterol Granuloma Metastasis Rhabdomyosarcoma Adenoma Chronic otitis media inflammatory debris

Prussak’s Space Cholesteatoma Pars flaccida cholesteatoma is the most common acquired (secondary) cholesteatoma. It is a soft-tissue mass found in the epitympanum lateral to the ossicles in Prussak’s space with erosion of the scutum and lateral epitympanic wall (red arrows). Prussak’s space cholesteatoma results from ingrowth of stratified squamous epithelium through the eardrum due to either a marginal perforation or invagination of a retraction pocket. It is a complication of recurrent acute otitis media, chronic OM, or eustachian tube dysfunction. Accumulation of keratin and squamous debris within the middle ear produces an inflammatory mass that erodes bone. Patients can present with conductive hearing loss and painless otorrhea. Complications include labyrinthiyis, vestibular dysfunction, facial nerve paresis, and SNHL.

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DDx

Case 10: What is the most likely diagnosis?

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Case 10: What is the most likely diagnosis?

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DDx: Subtemporalis Abscess

Case 10: What is the most likely diagnosis?

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Abscess of Dental Origin

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Cellulitis

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Suppurative Infection

Subtemporalis Abscess from Acute Otomastoiditis The middle ear, mastoid and pneumatized petrous bone communicate, and are extensions of the upper respiratory tract. Bacteria from the nasopharynx can reflux via the eustachian tube. If mucoperiosteal disease extends into the bone, coalescent mastoiditis can form. This is characterized by erosion of mastoid septae with the development of an intramastoid empyema. Complications of coalescent mastoiditis include direct extension to form an abscess (red arrows), perimastoid edema and cellulitis, and necrosis of the mastoid tip allowing spread of the infection inferiorly. Intracranial inflammatory complications can occur via direct extension of disease from the mastoid through a cortical defect or can be secondary to retrograde thrombophlebitis.

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DDx