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Neuroradiology Case of
the Week
Case 147
Alisa Johnson, Jeevak Almast, MD, Loris Cedeno, MD
and PL Westesson MD, DDS, PhD
Clinical
Presentation: The patient is a 9-year-old boy with Langerhan Cell Histiocytosis and history of chemotherapy and superior vena cava clot/syndrome. He now presents with new episodes of dizziness and emesis.
Radiological Findings:
CT: There is a rounded, hyperdense lesion in the medial aspect of the left temporal lobe. There is no evidence of associated mass effect surrounding this lesion.
MRI:There is a mass-like lesion located medially in the left middle
cranial fossa, well circumscribed, that is brightly hyperintense in
T1, FLAIR and T2 weighted images. It is producing severe mass effect over the left temporal horn. It contains a low attenuation rim in the T2 weighted sequence, suspicious for hemosiderin contents. (Patient went to OR).
MRI: 3 ½ years later after surgery. There is a popcorn lesion in the left mesiotemporal lobe region demonstrating a hemosiderin ring on T2 weighted images consistent with cavernous angioma. There is interval development of hypointense signal within the anterolateral portion consistent with hemorrhage.
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| Figure 1:
Axial CT. |
Figure 2: FLAIR. |
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| Figure 3: Axial T1. |
Figure 4: Axial T2. |
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| Figure 5: 3 years later - Axial FLAIR. |
Figure 6: 3 years later - Axial T1. |
Differential diagnosis: “Popcorn Ball” Lesion
1. Arteriovenous malformation
2. Hemorrhagic neoplasm
3. Calcified neoplasm ( i.e. oligodendroglioma)
Diagnosis: Cavernous angioma
Clinical Discussion: Cavernous angiomas are considered to be congenital vascular hamartomas composed of closely apposed endothelial-lined sinusoidal collections with slow blood flow and little to no neural tissue. Cavernous angiomas represent approximately 1% of intracranial vascular lesions and 15% of cerebrovascular malformations [1]. Cavernous angiomas can occur at any age, but they are most likely to occur in patients from 20-40 years.
Not all cavernous angiomas are associated with symptoms, but once patients become symptomatic, 40-50% present with seizures, 20% present with focal neurologic deficits, and 10-25% present with hemorrhage [1]. If the patient presents with a seizure disorder and the spin-echo pulse sequence is normal then gradient-echo pulse sequence can be used to help visualize any cavernous angiomas [2]. Nearly all cavernous malformations show evidence of recent and remote hemorrhage. The yearly risk of hemorrhage is approximately 0.2-2% per lesion per year [1]. Patients most at risk for hemorrhage are in the second or third decade of life. Because of the extruded blood products and the fact that some angiomas can grow slowly, the lesions may also produce seizures and a variety of neurologic findings similar to those expected of tumors. Symptoms depend on the location of the cavernous angiomas. Frontal and temporal lobes are the most common sites of occurrence, and 80-90% of the lesions are supratentorial. While the infratentorial location is less common, a patient with evidence of previous gross hemorrhage from the cavernous angioma is at increased risk of subsequent and progressive neurologic disability.
Although most cavernous angiomas can simply be followed up over time, surgical removal is an option in lesions causing significant morbidity. Cavernous angiomas are well circumscribed and surrounded by a gliotic rim; therefore, surgical removal is relatively simple.
Neuroimaging Discussion: Cavernous angiomas can be found anywhere in the brain but are rarely found in the spinal cord. The deep cerebral white matter, corticomedullary junction, and basal ganglia are common supratentorial sites, whereas the pons and cerebellar hemispheres are common posterior fossa sites.
CT findings are negative in 30-50% of cases. Positive CT finding included a well-delineated round or ovoid hyperdense lesion usually less than three centimeters in diameter. Cavernous angiomas will contain calcium approximately 40-60% of the time with little or no mass effect unless there has been a recent hemorrhage. On contrast enhanced CT, again there will be little to no enhancement unless mixed with other lesions such as a developmental venous anomaly.
Common findings on T1WI imaging are “popcorn ball” appearance of mixed hyperintense and hypointense blood-containing “locules.” Less often, acute hemorrhage can be seen on T1WI. T2WI will also show the “popcorn ball” lesions but with a mixed core and complete hypointense hemosiderin rim. FLAIR may show edema in an acute lesions and T2 GRE will show prominent susceptibility effect with hypointense “blooming” [3].
References:
- Jacobsen, James. Brain, cavernous angiomas. http://www.emedicine.com/radio/topic95.htm, June 2004.
- Grossman, RI. The Requisites, Neuroradiology. Mosby-Year Book Inc. St. Louis, 1994.
- Osborn AG. Diagnostic Imaging: Brain, 1st ed. Amirsys Inc: Altona, 2004.
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