Cerebral cavernous malformation (CCM) | |
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Histology of a cavernous hemangioma | |
Specialty | Oncology |
Cerebral cavernous malformation (CCM) is a cavernous hemangioma that arises in the central nervous system. It can be considered to be a variant of hemangioma, and is characterized by grossly large dilated blood vessels and large vascular channels, less well circumscribed, and more involved with deep structures, with a single layer of endothelium and an absence of neuronal tissue within the lesions. These thinly walled vessels resemble sinusoidal cavities filled with stagnant blood. Blood vessels in patients with cerebral cavernous malformations (CCM) can range from a few millimeters to several centimeters in diameter. Most lesions occur in the brain, but any organ may be involved. [1]
Clinical symptoms of central nervous system origin include recurrent headaches, focal neurological deficits, hemorrhagic stroke, and seizures, but CCM can also be asymptomatic. The nature and severity of the symptoms depend on the lesion's location.[ citation needed ]
In up to 30% there is a coincidence of CCM with a venous angioma, also known as a developmental venous anomaly. These lesions appear either as enhancing linear blood vessels or caput medusae, a radial orientation of small vessels that resemble the hair of Medusa from Greek mythology. These lesions are thought to represent developmental anomalies of normal venous drainage. These lesions should not be removed, as venous infarcts have been reported. When found in association with a CCM that needs resection, great care should be taken not to disrupt the angioma.[ citation needed ]
Familial forms of CCM occur at three known genetic loci. The gene for CCM1 encodes KRIT1 (krev interaction trapped 1), [2] [3] and has been found to bind to ICAP1alpha (integrin cytoplasmic domain associated protein alpha), [4] a beta1 integrin associated protein. A particular mutation in CCM1 (the Q455X mutation), accounts for a cluster of cases in the Southwestern United States. [5] This cluster, particularly in northern New Mexico, is an example of the founder effect; it has been traced back to early Spanish settlers. [6]
The gene for CCM2 encodes a protein named malcavernin that contains a phosphotyrosine binding domain. [7] The exact biological function of CCM2 is not clear. Recently, it has been shown that CCM1 and CCM2 proteins as well as ICAP1alpha form a macromolecular complex in the cell. In addition, it appears that CCM2 protein may function as a scaffolding protein for MAP kinases that are essential in p38 activation responding to osmotic stress including MEKK3 and MKK3. [8] It also binds to Rac and actin. Therefore, CCM2 protein is also called OSM (osmosensing scaffold for MEKK3).[ citation needed ]
The CCM3 gene is the most recently identified CCM gene . CCM3 is known as PDCD10 (programmed cell death 10), which was initially identified as a gene that is up-regulated during the induction of apoptosis (cell death) in TF-1, a human myeloid cell line. [9] The precise role of the PDCD10 protein in the CCM pathway is not clear. It is recently shown that PDCD10 forms a complex with CCM1 protein (KRIT1) and CCM2 protein (OSM). PDCD10 interacts directly with OSM independent of KRIT1-OSM interaction. Research is ongoing to determine the function and properties of all three CCM gene products as well as the reaction pathways in which they are involved.[ citation needed ]
Evidence suggests that a fourth gene, CCM4, may also cause CCM. [10] Mutations in these genes account for 70 to 80 percent of all cases of cerebral cavernous malformations. The remaining 20 to 30 percent of cases may be due to other, still unidentified, genes. Recently it has been shown that the deletion of CDC42 in endothelial cells elicits cerebral vascular malformations, suggesting that it may be a fourth gene involved in CCM pathology. [11]
Recently, gain of function mjutations in Pik3ca has been reported in both sporadic and familial CCM, [12] [13] suggesting that like cancer, CCM lesions need to inhibit tumor suppressor genes and activate oncogenes. [12]
Many molecular mechanisms have been identified in CCM pathology. In 2015 it was reported that the endothelial cells forming cerebral vascular malformations undergo an endothelial to mesenchymal transition in both sporadic and familial CCM [14] [15]
CCM mutant endothelial cells have been reported to undergo clonal expansion and be able to recruit non-mutant cells into the lesions [16] [17] Recently, immunothrombosis and hypoxia have also been reported to be dysregulated in CCM. [18]
Diagnosis is generally made by magnetic resonance imaging (MRI), particularly using a specific imaging technique known as a gradient-echo sequence MRI, which can unmask small or punctate lesions that may otherwise remain undetected. These lesions are also more conspicuous on FLAIR imaging compared to standard T2 weighing. FLAIR imaging is different from gradient sequences. Rather, it is similar to T2 weighing but suppresses free-flowing fluid signal. Sometimes quiescent CCMs can be revealed as incidental findings during MRI exams ordered for other reasons. Many cavernous hemangiomas are detected "accidentally" during MRIs searching for other pathologies. These "incidentalomas" are generally asymptomatic. In the case of hemorrhage, however, a CT scan is more efficient at showing new blood than an MRI, and when brain hemorrhage is suspected, a CT scan may be ordered first, followed by an MRI to confirm the type of lesion that has bled. [19] Sometimes the lesion appearance imaged by MRI remains inconclusive. Consequently, neurosurgeons will order a cerebral angiogram or magnetic resonance angiogram. Since CCMs are low flow lesions (they are hooked into the venous side of the circulatory system), they will be angiographically occult (invisible). If a lesion is discernible via angiogram in the same location as in the MRI, then an arteriovenous malformation (AVM) becomes the primary concern.[ citation needed ]
Treatment of symptomatic CCM is only via surgery, depending on the location of the lesions. There are no pharmaceuticals currently available to treat CCM. [18]
The incidence in the general population is roughly 0.5%, and clinical symptoms typically appear between 20 and 30 years of age. [20] Once thought to be strictly congenital, these vascular lesions have been found to occur de novo . It may appear either sporadically or exhibit autosomal dominant inheritance.[ citation needed ]
Hereditary hemorrhagic telangiectasia (HHT), also known as Osler–Weber–Rendu disease and Osler–Weber–Rendu syndrome, is a rare autosomal dominant genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, and often in organs such as the lungs, liver, and brain.
Sturge–Weber syndrome, sometimes referred to as encephalotrigeminal angiomatosis, is a rare congenital neurological and skin disorder. It is one of the phakomatoses and is often associated with port-wine stains of the face, glaucoma, seizures, intellectual disability, and ipsilateral leptomeningeal angioma. Sturge–Weber syndrome can be classified into three different types. Type 1 includes facial and leptomeningeal angiomas as well as the possibility of glaucoma or choroidal lesions. Normally, only one side of the brain is affected. This type is the most common. Type 2 involvement includes a facial angioma with a possibility of glaucoma developing. There is no evidence of brain involvement. Symptoms can show at any time beyond the initial diagnosis of the facial angioma. The symptoms can include glaucoma, cerebral blood flow abnormalities and headaches. More research is needed on this type of Sturge–Weber syndrome. Type 3 has leptomeningeal angioma involvement exclusively. The facial angioma is absent and glaucoma rarely occurs. This type is only diagnosed via brain scan.
Lymphangiomas are malformations of the lymphatic system characterized by lesions that are thin-walled cysts; these cysts can be macroscopic, as in a cystic hygroma, or microscopic. The lymphatic system is the network of vessels responsible for returning to the venous system excess fluid from tissues as well as the lymph nodes that filter this fluid for signs of pathogens. These malformations can occur at any age and may involve any part of the body, but 90% occur in children less than 2 years of age and involve the head and neck. These malformations are either congenital or acquired. Congenital lymphangiomas are often associated with chromosomal abnormalities such as Turner syndrome, although they can also exist in isolation. Lymphangiomas are commonly diagnosed before birth using fetal ultrasonography. Acquired lymphangiomas may result from trauma, inflammation, or lymphatic obstruction.
The phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha, also called p110α protein, is a class I PI 3-kinase catalytic subunit. The human p110α protein is encoded by the PIK3CA gene.
Angiopoietin-1 receptor also known as CD202B is a protein that in humans is encoded by the TEK gene. Also known as TIE2, it is an angiopoietin receptor.
Krev interaction trapped protein 1 or Cerebral cavernous malformations 1 protein is a protein that in humans is encoded by the KRIT1 gene. This gene contains 16 coding exons and is located on chromosome 7q21.2. Loss of function mutations in KRIT1 result in the onset of cerebral cavernous malformation. Cerebral cavernous malformations (CCMs) are vascular malformations in the brain and spinal cord made of dilated capillary vessels.
Integrin beta-1-binding protein 1 is a protein that in humans is encoded by the ITGB1BP1 gene.
Transcription factor SOX-18 is a protein that in humans is encoded by the SOX18 gene.
The CCM2 gene contains 10 coding exons and an alternatively spliced exon 1B. This gene is located on chromosome 7p13 and loss of function mutations on CCM2 lead to the onset of Cerebral Cavernous Malformations (CCM) illness. Cerebral cavernous malformations (CCMs) are vascular malformations in the brain and spinal cord made of dilated capillary vessels.
Programmed cell death protein 10 is a protein that in humans is encoded by the PDCD10 gene.
Serine/threonine-protein kinase 24 is an enzyme that in humans is encoded by the STK24 gene located in the chromosome 13, band q32.2. It is also known as Mammalian STE20-like protein kinase 3 (MST-3). The protein is 443 amino acids long and its mass is 49 kDa.
Angiogenic factor with G patch and FHA domains 1 is a protein that in humans is encoded by the AGGF1 gene.
Striatin is a protein that in humans is encoded by the STRN gene.
Cavernous venous malformations present as rounded, bright red or deep purple, spongy nodules, occurring chiefly on the head and neck and may involve both the skin and the mucous membranes.
Cobb syndrome is a rare congenital disorder characterized by visible skin lesions and spinal angiomas or arteriovenous malformations (AVMs). The skin lesions of Cobb syndrome typically are present as port wine stains or angiomas, but reports exist of angiokeratomas, angiolipomas, and lymphangioma circumscriptum. The intraspinal lesions may be angiomas or AVMs and occur at levels of the spinal cord corresponding to the affected skin dermatomes. They may in turn produce spinal cord dysfunction and weakness or paralysis.
Sinus pericranii (SP) is a rare disorder characterized by a congenital epicranial venous malformation of the scalp. Sinus pericranii is an abnormal communication between the intracranial and extracranial venous drainage pathways. Treatment of this condition has mainly been recommended for aesthetic reasons and prevention of bleeding.
Parkes Weber syndrome (PWS) is a congenital disorder of the vascular system. It is an extremely rare condition, and its exact prevalence is unknown. It is named after British dermatologist Frederick Parkes Weber, who first described the syndrome in 1907.
Cavernous hemangioma, also called cavernous angioma, venous malformation, or cavernoma, is a type of venous malformation due to endothelial dysmorphogenesis from a lesion which is present at birth. A cavernoma in the brain is called a cerebral cavernous malformation or CCM. Despite its designation as a hemangioma, a cavernous hemangioma is not a tumor as it does not display endothelial hyperplasia. The abnormal tissue causes a slowing of blood flow through the cavities, or "caverns". The blood vessels do not form the necessary junctions with surrounding cells, and the structural support from the smooth muscle is hindered, causing leakage into the surrounding tissue. It is the leakage of blood, referred to as hemorrhage, that causes a variety of symptoms known to be associated with the condition.
Fibro-adipose vascular anomaly, also known as FAVA, is a type of vascular anomaly that is both rare and painful. FAVA is characterized by tough fibrofatty tissue taking over portions of muscle, most often contained within a single limb. FAVA also causes venous and/or lymphatic abnormalities.
PIK3CA-related overgrowth spectrum (PROS) is an umbrella term for rare syndromes characterized by malformations and tissue overgrowth caused by somatic mutations in PIK3CA gene. In PROS diseases individuals malformations are seen in several different tissues such as skin, vasculature, bones, fat and brain tissue depending on the specific disease.