Multiple cavernous malformations (AKA cavernomas) with associated large hemispheric developmental venous anomaly (AKA DVA or venous angioma)

Findings

CT head: Multiple areas of intracranial hemorrhage in the left hemisphere. There is thrombosis of the superior sagittal sinus and a left cortical vein. Two focal hyper dense masses are seen in the left occipital lobe and the medial left temporal lobe.
MRI and MRV brain: Multiple intraaxial masses in the left cerebral hemisphere seen in the temporal lobe, basal ganglia, occipital lobe, and genu of the corpus callosum which show blooming artifact on gradient echo images, and a hypo intense rim on T2-weighted images. There is a large left hemispheric venous angioma with dilated medullary veins which drain to the internal cerebral vein best seen on post contrast images. The anterior superior sagittal sinus is hypoplastic or stenotic.
Cerebral angiogram: No evidence of aneurysm or AVM. There is a large left venous angioma draining the entire left hemisphere into the internal cerebral vein then to the vein of Galen. Left cortical vein thrombosis, nonocclusive posterior superior sagittal sinus thrombus, and absence of the anterior superior sagittal sinus.

Differential diagnosis:
- Multiple arteriovenous malformations
- Multiple cavernous malformations with large venous angioma and sagittal sinus stenosis and partial thrombosis
- Multiple cavernous malformations with venous stasis due to sinus stenosis and partial thrombosis
- Multiple hemorrhagic metastases with leptomeningeal enhancement
- Multiple calcified metastases and leptomeningeal enhancement
- Sturge Weber with arteriovenous malformations


Diagnosis: Multiple cavernous malformations (AKA cavernomas) with associated large hemispheric developmental venous anomaly (AKA DVA or venous angioma)


Key points

The diagnosis is favored over cavernomas with venous stasis because:
- There is a known association between cavernous malformations and developmental venous anomalies.
- The cerebral angiogram shows an embryologic drainage pattern.


Cavernous malformations

Clinical
- Presentation: Seizure 50%, neurologic deficit 25%
- Pathology: Collection of endothelial lined, blood filled vessels without intervening normal brain
- Genetics: Multiple cavernous malformations can be seen with an autosomal dominant chromosomal abnormality
- Prevalence: 0.5%
- 75% solitary, sporadic lesion
- 10-30% multiple, familial
- Hemorrhage rate: Sporadic 0.25-0.75%

- Associated anomalies:
Developmental venous anomaly
Superficial siderosis
Cutaneous findings: café au lait spots, cherry angiomas

Imaging:
- Cerebral angiography: Most common angiographically occult vascular malformation, i.e. not detectable. May be associated with a venous angioma
- MRI: Popcorn ball appearance; mixed signal intensity core with a hypo intense hemosiderin rim; prominent susceptibility artifact ("blooming"). Diffusion usually normal
- CT: Negative in 30-50%; may appear as an ovoid hyper dense lesion. 40-60% have Ca2+


Developmental venous anomaly (AKA venous angioma)

Clinical
- Embryology: Felt to be secondary to arrested medullary vein development resulting in persistence of large primitive deep embryonic white matter veins
- Most common vascular malformation at autopsy
- Usually asymptomatic
- 15-20% associated with cavernous malformations
- Radially oriented dilated medullary veins
- Hemorrhage risk increases with occlusion of the draining vein. Risk felt to be 0.15% per lesion/year
- Multiple can occur with blue rubber-bleb nevus syndrome

Imaging
- Prevalence: 2.5-9% of MRI scans
- Contain normal intervening brain
- Dilated medullary veins have the "medusa head" or umbrella-like appearance; located often at the angle of the ventricle; stellate, tubular vessels converse on a collector vein which drains into a dural sinus/ependymal vein
- Differential diagnosis includes dural sinus occlusion with venous stasis and collateral drainage.
- Cerebral angiography: Most common angiographically occult vascular malformation, i.e. not detectable; may be associated with a venous anomaly
- MRI:
T1 and T2 weighted images: Can be normal if small, or see flow void if large enough
T1+C: Stellate pattern of tubular vessels of strong enhancement draining to a collector vein to a dural sinus/ependymal vein
MRV: Demonstrates medusa head and drainage pattern
CT: Usually normal. Parenchymal hemorrhage if draining vein occluded

Squamous cell carcinoma of the external auditory canal

Findings

Figure 1, Figure 2, Figure 4, Figure 5 are axial and coronal T1 and T2 weighted images respectively. Figure 3 and Figure 6 are post contrast T1 weighted fat saturated images. A soft tissue mass is seen in the above images in the external auditory canal appearing isointense on T1 images and hyperintense on T2 images with post contrast enhancement. The middle ear is invaded with no intracranial extension. The internal carotid artery is uninvolved.

Differential Diagnosis:
- Squamous cell carcinoma of the external auditory canal
- Debris in the external auditory canal
- Malignant otitis externa
- External auditory canal cholesteatoma
- Keratosis obturans
- Medial canal fibrosis


Diagnosis: Squamous cell carcinoma of the external auditory canal


Carcinomas of the external auditory canal are rare and form less than 0.2% of head and neck malignancies. Various histological subtypes have been described, the commonest being squamous cell carcinoma followed by adenoid cystic carcinoma.

Squamous cell carcinoma of the external auditory canal is predominantly a disease of the elderly with slight male preponderance. Exposure to radiation therapy for head and neck malignancies, especially nasopharyngeal carcinoma, is a risk factor. The tumor is locally aggressive with a relatively lower tendency to metastasize.

Patients typically present with otorrhea, otalgia, and bloody discharge from the ear. Visible necrotic mass, swelling, tinnitus, hearing loss, facial palsy, otitis externa and otitis media are other presenting features.

Extent, description and staging of the tumor is based primarily on imaging as the region is inaccessible to a complete and satisfactory clinical examination. CT scan of the temporal bone is a routine investigation, and is done to look for bony erosion. Small tumor extent and more outer location of ear malignancy such as the auricle or external ear canal has better prognosis with a higher 5-year survival rate.

Surgical excision is the mainstay of management. There is no consensus over the surgical procedure and approaches vary from en bloc resection to piecemeal removal of the tumor. Invasion of the carotid, middle or posterior fossa renders the tumor inoperable. Any nodal involvement is regarded as advanced disease (stage III and IV) and changes the stage irrespective of the T status of the University of Pittsburgh TNM Classification.

In early stages the tumor is treated by en bloc resection, confirming negative margins, with post operative radiotherapy not offering a documented survival advantage over surgery alone. On the other hand, in advanced stages surgery is routinely followed by radiation and topical chemotherapy (5-FU mostly).

Right cerebellar encephalomalacia

Findings

There is increased signal in the right cerebellar hemisphere on T2 weighted images. On FLAIR images, there is decreased signal arising from the right cerebellar hemisphere secondary to fluid attenuation. There is also apparent diffusion restriction in the left cerebellar hemisphere on DWI and ADC map images. In fact the L side is the normal side.


Diagnosis: Right cerebellar encephalomalacia


Discussion

Encephalomalacia is usually a consequence of aging and/or brain insult, and in this case, the patient had a prior right cerebellar infarct. The brain parenchyma becomes atrophic and becomes replaced by CSF. Encephalomalacia usually does not cause acute symptoms and was likely not the cause of this patient's symptoms.


Radiologic overview

Diffusion weighted imaging is the most sensitive MR sequence to detect acute stroke. Changes in diffusion weighted images can be seen as early as 30 minutes after insult. At the cellular level, there is random movement and diffusion of water through cellular membranes. In tissues with greater water mobility, there is increased signal loss on diffusion weighted images. In stroke, there is a disruption of cellular membrane ion pumps, which leads to an influx of water into the intracellular space due to osmosis. Intracellular water does not move as freely as extracellular water and this decreased movement leads to increased signal on diffusion weighted images. An increased signal on diffusion weighted images alone is not sufficient to diagnose acute ischemia however, as tumor, infection and trauma can increase intra- and extra-cellular water leading to increased signal on DWI. The apparent diffusion coefficient map diminishes the increased signal associated with increased extracellular water and takes into account only the mobility of water. As the movement of water decreases in ischemic cells, the water diffusion coefficient decreases. This manifests as signal loss on ADC map images. Extracellular fluid on ADC map images will remain bright. Thus, acute ischemia is identified by increased signal on DWI and associated dark signal in the same region on ADC map. The use of DWI and ADC map images is sensitive (88-100%) and specific (86-100%) for acute stroke.

In this patient, there was a sequence of DWI images that demonstrated increased signal in the left cerebellar hemisphere. However, on ADC map images, there was no associated loss of signal. The adjacent right cerebellar encephalomalacia (and bright signal due to the high extracellular water e.g. CSF), gave the illusion of signal loss in the left cerebellar hemisphere. On T2 and FLAIR images, acute ischemia shows up as increased signal. In this case, there was no increased T2 signal throughout the brain parenchyma. The encephalomalacia in the right cerebellar hemisphere shows up bright on T2 weighted images due to CSF replacement of brain parenchyma.

Lymphangioma with components of hemangioma

Findings

Multilobular, infiltrative mass posterior to the lower cervical/upper thoracic spine, which is soft tissue density on CT and on MR is T1 iso intense to muscle, T2 hyper intense, homogeneously enhances, and shows evidence of flow voids. There is also enhancement of the adjacent spinous process.

Differential diagnosis:
- Hemangioma
- Lymphangioma
- Liposarcoma


Diagnosis: Lymphangioma with components of hemangioma


Key points

Endothelial malformations are currently divided into hemangiomas and vascular malformations.
Previously these lesions were categorized and named according to the channel size and contained fluid: i.e. capillary, strawberry and cavernous hemangiomas for blood containing lesions; and lymphangiomas or cystic hygromas for lymph containing lesions.
Vascular malformations are not true neoplasms and they are subdivided into high-flow and low-flow groups.
High-flow vascular malformations have an arterial component and include both arteriovenous malformations and arteriovenous fistulas.
Low–flow vascular malformations include lymphangiomas and venous malformations.
Hemangiomas are true, benign, neoplasms of the endothelium, and represent the most common tumor of childhood.
Hemangiomas are characterized by their absence or subtlety at birth, followed by a period of rapid proliferation, and then eventual involution.
MRI and ultrasound are the main modalities used for imaging hemangiomas and vascular malformations.

Goals of imaging of hemangiomas and vascular malformations are
- lesion characterization
- anatomic location/extent


MR features

Hemangiomas are usually isointense on T1, hyper intense on T2, and show diffuse enhancement.

Low flow vascular malformations:
- Venous malformations are dilated, "serpentine", lesions, which are hyper intense on T2 and intermediate signal on T1, and may have slow contrast enhancement of the vessel channels. Low signal phleboliths may be seen.
- Lymphangiomas tend to "infiltrate" the adjacent anatomic structures, and contain variably sized cystic spaces which are variable on T1 (due to variable protein content), hyper intense on T2 and do not demonstrate enhancement of the central cystic spaces.
- High-flow vascular malformations are characterized by flow voids suggestive of rapid blood flow.


Treatment

Treatment of hemangiomas is usually conservative.
Treatment of low flow vascular malformations is currently percutaneous sclerosis.
Treatment of high flow vascular malformations is arterial embolization.

Dural plasmacytoma

Findings


There is an extra-axial, dural based mass predominantly in the high left posterior parietal region which is relatively isointense signal on TI (Figure 1) and T2 (Figure 2) sequences.
The lesion demonstrates homogeneous contrast enhacement on post contrast sequences, (Figure 3). Extension along the interhemispheric fissure (Figure 4), encasement of the superior sagittal sinus (Figure 4) and extension across midline to the right (Figure 4) is demonstrated.


Diagnosis: Dural plasmacytoma


Plasmacytomas of the dura are uncommon plasma cell tumors that may occur as a solitary neoplasm or, more commonly, in association with multiple myeloma. The latter is usually accompanied by multiple lytic lesions of the skull. In distinction, solitary craniocerebral plasmacytomas are relatively benign and potentially curable. Therefore, distinction between the two has important clinical consequences. The differential diagnosis for dural plasmacytoma includes metastasis, lymphoma, dural sarcoma, plasma cell granuloma and meningioma.

Dural plasmacytomas are often confused with meningiomas (the most common extra-axial neoplasm found in adults) as the two have similar features and imaging characteristics. Both occur more commonly in women during the 5th decade of life with a predilection for similar sites of involvement including the cerebral convexities, sphenoid ridge, falx, and tentorium. On MR both may appear nearly isointense to brain on T1W images and iso- to hyperintense on T2W images with marked contrast enhancement. A characteristic "dural tail" and intratumoral calcifications may be seen in both lesions. Other manifestations of intracranial plasmacytoma may include diffuse leptomeningeal disease and rarely, intracerebral lesions with vasogenic edema.

These patients may present with intracranial hypertension and/or focal neurological signs from the dural origin of the tumor. Clinically, individuals with solitary dural plasmacytomas can be distinguished from those with multiple myeloma by the absence of hypercalcemia, renal insufficiency, anemia, lytic osseoues lesions, bone marrow plasmacytosis, and elevated serum or urinary paraprotein. Following surgical decompression and/or local radiotherapy for a solitary dural plasmacytoma, the prognosis is fairly good. This is in contrast to patients with plasmacytoma and multiple myeloma who typically have a much poorer prognosis.

CNS epidermoid

Findings

Lateral ventricles and third ventricle are dilated. A mildly heterogeneous low density mass involves the dorsal aspect of the midbrain near the anticipated position of the pineal gland and cerebral aqueduct . MR confirms a mass in the region of the cerebral aqueduct extending into the fourth ventricle inferiorly and superiorly into the region of the posterior third ventricle. Closely following CSF, the mass demonstrates decreased T1 signal and increased T2 signal. There is restricted diffusion. There is no associated abnormal enhancement on the C+ sagittal images.


Diagnosis: CNS epidermoid.


Discussion

Intracranial epidermoid represents up to 1.8% of all primary intracranial tumors. They are the most common congenital intracranial tumor. They represent the third most common CPA/IAC mass after schwannoma and meningioma.

They most commonly present with headaches and possibly with cranial nerve palsies, typically of the 5th, 7th, and 8th nerves. They may remain clinically silent for many years. There is no gender predilection. Their presentation peaks at age 40 and has a range of 20 – 60 years of age.
As the have epithelia components they grow slowly. They can cause chemical meningitis if they leak and rarely have been reported to undergo malignant transformation to squamous cell carcinoma.
Treatment involves microsurgical resection which can be complicated by encasement of surrounding structures. Recurrence is common if they are not completely resected and seeding of the subarachnoid space has been reported.


Radiologic Overview

Epidermoid typically follow CSF density and may encase surrounding structures. Most commonly they are found in the CP angle (40-50%). They can also commonly be found in the fourth ventricle and middle cranial fossa, typically para-sellar. Occasionally they can be found within the skull and spine.
CT findings: Most are hypo dense, although 10-25% will have calcifications. They typically do not show post contrast enhancement however may have minimal enhancement at the margin. There is a rare variant which may be dense secondary to hemorrhage or high protein.
MRI findings: Again they are similar to CSF on T1 and T2 pulse sequences. On T1 they are slightly hyper intense to CSF and on T2 they are isointense to slightly hyper intense to CSF. Intensity will be altered depending on the cyst contents. Minimal enhancement can be seen at the margins. They key distinguishing feature is the appearance on diffusion weighted images which is markedly intense, "light bulb bright". On ADC mapping they are isointense to brain parenchyma.
The differential diagnosis includes arachnoid cyst, which follow CSF signal on all sequences and does not show restricted diffusion. Arachnoid cysts typically displace adjacent structures whereas epidermoid lesions encase them. Cystic neoplasm's often enhance and do not follow CSF signal. Dermoid cysts are typically heterogeneous on MR and more closely follow fat signal characteristics. Additionally dermoid are typically midline. Inflammatory cysts typically enhance and have surrounding edema and/or gliosis.

Sturge-Weber syndrome

Findings

Gyriform calcifications are observed over the left occipital lobe in the CT exam. The MRI demonstrates atrophy of the left cerebral hemisphere. There is enlargement of the left choroid plexus which demonstrates homogeneous enhancement post contrast. There is also gyriform enhancement post contrast most significantly on the left occipital lobe. There is diffuse enhancement of the subcutaneous tissues over the left eye.


Diagnosis: Sturge-Weber syndrome.


Key points

Classically the patients have a facial port-wine stain, ipsilateral intracranial abnormalities, contralateral hemiparesis, hemiatrophy, mental retardation, and homonymous hemianopia. The severity of these features varies widely patient to patient. Commonly the patients will have glaucoma on the affected side. Seizures are also very common.
Only 8% of patients with port-wine stains have Sturge-Weber Syndrome. 13% of Sturge-Weber syndrome patients do not have a facial angioma.
There is no clear genetic link at this time. There is no sex or race Predilection and it is very seldom seen more than once in the same family. Several different chromosomal abnormalities have been implicated.
Radiographically one can see "tram track calcifications" which are leptomeningeal calcifications like those seen on the CT image.
MRI can demonstrate the angiomatous abnormalities. In this case the cutaneous capillary angioma (port-wine stain) is well demonstrated as is the meningeal angiomatosis over the left occipital lobe. Cerebral hemiatrophy is well demonstrated by MRI as is the choroidal angiomatosis.
Multiple therapies are employed in these patients. The port-wine stains can be "removed" with laser treatments. Seizures can be treated with anticonvulsants. Refractory seizures can be treated surgically. The surgeries can be as extensive as a hemispherectomy.