Vascular Malformations and Hemangiomas

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Categories:

• Capillary telangiectasia

• Cavernous hemangioma

• Familiarl multiple cavernous angiomatosis

• Arterial hamartomas

• Arteriovenous malforamtion (AVM)

• Venous malformation  

• Aneurysmal malformation of the great vein of Galen

Capillary telangiectasia: Head

GENERAL:

• Incidence: The incidence is difficult to estimate since most of them are clinical silent.

• Age/sex: They are most common seein in the 4^th to 8^th decade.

• Multiplicity: Mostly solitary and occasionally multiple.

• Clinical: Spontaneous hemorrhage is extremely uncommon.

• Location: Most common in the pons and are usually found near the median raphe.

GROSS PATHOLOGY: It varies from a porly defined pink area to a lesion that resembles a small cluster of petechial hemorrhage, depending on how engorged are the vessels.

HISTOPATHOLOGY: They occur as clusters of enlarged and varicosed capillaries separated by neural tissue. The caliber of the vessels is highly variable, however, there is no increase in number of vessels. The draining vein is enlarged but not varicose and no abnormal arterial vessels are present. The pial vessels are normal.

Cavernous hemangioma: Head  

GENERAL:

• Incidence: About 5% of the vascular malformations diagnosed by angiography and histologically verified.

• Age/sex: 3^rd to 5^th decades, also seen in children and eldery patients. Male are more affected.

• Multiplicity: Solitary lesions are 3 times more frequent than solitary lesions.

• CLINICAL:

• About 1/3 of the partents present with seizure, 1/3 presents as intracerebral hemorrhage and 1/3 present as space-occupying lesions.

• Spontaneous hemorrhage, may be recurrent or even fatal, is common. Cortical and subcortical hemangiomas are specifically related to seizures.

LOCATION AND SIZE:

• 75% are supratentorial, the pons is the prefered site of infratentorial cavernous hemangiomas, rare in the cerebellum and spinal cord.

• Cerebral cavernous hemangiomas are usually subcortical, most common region are the central fissure. They are also seen in the temporal lobe, basal ganglia, and third ventricles. Dura and nerve roots are occasionally involved.

• Size: Most are less than 1 to 2 cm but large and extensive lesions can be seen.

GROSS PATHOLOGY: Lobulated architecture surrounded by brown to golden-brain stained tough parenchymal tissue.

HISTOPATHOLOGY: Numerous thin-walled vascular spaces with back-to-back arrangement and no intervening neural parenchyma. There is dramtic variation in vessel caliber. Some of the vessels are thicker than a normal capillary and may be calcified. Thrombosis with organization is common. Evidence of prior hemorrhage is almost always present. Draining veins, often thickened, dilated and tortous, may be found on the overlying pia.

Familiarl multiple cavernous angiomatosis: Head

GENETICS:

• Some cavernous hemangiomas occur in an autosomal dominant fashion. The pattern of inheritance is heterogeneous. The genes have been located to chromosome 7q21-q22 (CCM1 or KEIT1 gene) [Sahoo T et al., 1999], 7p15-13 (CCM2) [Craig HD, 1998], and 3q25.2-27 (CCM3) [Gunel M, 1996]. Muations of KRIT1 gene, a tumor suppressor gene, is also related.

• The families with familial cavernous hemangiomas that have been described so far are all Hispanic.

Arterial hamartomas: Head

COMMENT: By definition, arterial hamartomas are composed purely of arteries. However, this is a poorly defined entity that is only encountered very rarely. They may well be an AVM with substantial amount of arterial component.

Arteriovenous malforamtion (AVM): Head

GENERAL:

• Prevalence: About 0.1% of the general population. They account for about 1.5% of intracranial tumors.

• Age/sex: Usually presents before 40 years of age.

• Clinical:

• Ruptured AVM are responsible for about 1% of stroke and is a very common cause of spontaneous hemorrhage in young adults and has a markedly increased tendency to rupture in cocaine user. Initial bleeding tends to be most common in the 2^nd, 3^rd, and 4^th decades of life.

• Seizures may also be an associated feature but it less common. Those associated with seizure are often located in the cerebral cortex.

• “Steal phenomenon”, presenting as a progressive neurologic ysmtoms resulting from ischemia due to diversion of the cerebral blood flow by the malformation, can be an unusual presentation.

• Fate: the clinical course cannot be easily predicted: they may remain static, grow, or even regress.

• Association: patient have AVM have increased risk for other vascular anomalies. About 10-58% of the patients have classic aneurysms. These aneurysmS may occur distant from the AVM.

• Complications of treatment: the average incidence of complication from embolization is about 10%.

LOCATION: Areas supplied by the middle cerebral arteries are the common sites of AVM. They are found most commonly in the cerebral hemispheres as a superficial lesion that also involves the leptomeningeal vessels, although deep lesions are also present. The cerebellum, brain stem, and spinal cord are rarely involved.

BLOOD SUPPLY: Superficial AVM are fed by cortical branches of major cerebral arteries. Deep AVM are fed by by superficial and deep arteries. Some of them are fed through the dura from branches of the external carotid or vertebral arteries. Deeper portions may be fed by the choroidal arteries or penetrating arteries. Malformations confined to the cortex almost always drain superficially through cortical veins, whereas larger or deeper ones follow superficial as well as deep routes.

NEUROIMAGING: High-flow angiopathy: feeding artery may have irregular stenoses, termed "high-flow angiopathy", which angiographically resemble those of moyamoya disease and preclude the passage of catheters for embolization.

GROSS PATHOLOGY: They appear as hemorrhagic lesions with a spongy look on cross sections. Superficial lesions are often associated with gray, thickened, and rusty pigmented leptomeningeal membrane overlying the lesion. There is atrophy in the cortex subjacent to the lesion.

HISTOPATHOLOGY:

• There is a mixture of markedly abnormal arteries and vein. Internal elastic lamina of the arteries may be reduplicated, interrupted and distorted. The muscularis media varies greatly in thickness. There are also secondary changes including atherosclerosis, thrombosis and organization.

• The overlying cortex shows focal loss of neurons accompanied by gliosis.

Venous malformation: Head

GENERAL:

• Location: They are relatively uncommon in the brain but they are the most common vascular abnormality in the spinal cord and its meninges.

• In the brain, it is most commonly seEn in the territory supplied by the middle cerebral artery.

• In the spinal cord, the segments caudal to the 5^th or 6^th thoracic segments are usually involved and may only spans for a few segments. The dorsal but not the ventral surface is affected. The venous malformation is drained by a few varicose radicular veins. The lesion may extend to the dorsal nerve roots.

HISTOPATHOLOGY: There are numerous veins in the pia that are thickened by muscular hyperplasia and hyaline collagenous tissue. These vessels vary greatly in diameter.