Cavernous hemangioma
Cavernous hemangioma, also called cavernous angioma, cavernoma, or cerebral cavernoma is a type of benign vascular tumor or hemangioma, where a collection of dilated blood vessels form a lesion. Because of this, blood flow through the cavities, or caverns, is slow. Additionally, the cells that form the vessels do not form the necessary junctions with surrounding cells. Also, the structural support from the smooth muscle is hindered, causing leakage into the surrounding tissue. It is the leakage of blood, known as a hemorrhage, from these vessels that causes a variety of symptoms known to be associated with this disease.
Symptoms
Individuals with this condition may have symptoms such as seizures due to the compression of the brain tissue or hemorrhaging of angioma scarring surrounding tissue, an intraparenchymal hemorrhage, double vision or other vision problems, language difficulties, memory loss, and incidental hydrocephalus. Minor symptoms may include headaches, weakness or numbness in the arms or legs, and ataxia. When it occurs in the liver it is usually asymptomatic but may present as pain in the upper right abdomen, a feeling of fullness after eating only a small amount of food, lack of an appetite, nausea, and vomiting. In the eye, as the lesion changes in size it will involve the extraocular muscles and optic nerve, and patients report double vision, decreased vision, and progressive proptosis.Presentation
Cavernous hemangiomas can arise nearly anywhere in the body where there are blood vessels. They are often described as raspberry-like structures because of the bubble-like caverns. Unlike the capillary hemangiomas, cavernous ones can be disfiguring and do not tend to regress.Causes
Most cases of cavernomas are thought to be congenital; however they can develop over the course of a lifetime. While there is no definitive cause, research shows that genetic mutations result in the onset. Congenital hemangiomas that appear on the skin are known as either vascular or red birthmarks.Familial cerebral cavernous malformations are known to occur. The mutations may be inherited in an autosomal dominant fashion or occur sporadically. Overall familial disease is responsible for one third to one half of cases. In the US approximately 50% of Hispanic patients with cerebral cavernous malformations have a familial form: in contrast in this occurs in only 10 to 20% of Caucasians. The reason for this difference is not presently known.
Several genes – K-Rev interaction trapped 1, Malcavernin and Programmed cell death protein 10 – have been identified as having mutations thought to be related to these lesions. These genes are located at 7q21.2, 7p13 and 3q25.2-q27 respectively. These lesions are further discussed in the Online Mendelian Inheritance in Man site – the reference numbers are OMIM 116860, OMIM 603284 and OMIM 603285 respectively.
Variations
Cerebral cavernomas
Cavernous hemangiomas located in the brain or spinal cord are referred to as cerebral cavernomas or more usually as cerebral cavernous malformations, and can be found in the white matter, but often abut the cerebral cortex. When they contact the cortex, they can represent a potential seizure focus for the patient. Unlike other cavernous hemangiomas, there is no tissue within the malformation and its borders are not encapsulated. Therefore, they can change in size and number over time.Liver cavernous hemangioma
Cavernous hemangiomas are the most common benign tumors of the liver. Usually one tumor exists, but multiple lesions can occur in the left or right lobe of the liver in 40% of patients. Their sizes can range from a few millimeters to 20 centimetres. Those over 5 cm are often referred to as giant hemangiomas.Eye cavernous hemangioma
In the eye, it is known as orbital cavernous hemangioma and is found in women more frequently than men, most commonly between the ages of 20–40. This neoplasm is usually located within the muscle cone, which is lateral to the optic nerve. It is not usually treated unless the patient is symptomatic. Visual impairment happens when the optic nerve is compressed or the extraocular muscles are surrounded.Mechanism
There are several known causes for cavernous hemangiomas, but some cases are still unknown. Radiation treatment used for other medical conditions has been suggested to cause cavernous malformation in some patients.Hemangioma tumors are a result of rapid proliferation of endothelial cells and pericytic hyperplasia, or the enlargement of tissue as a result of abnormal cell division pericytes. The pathogenesis of hemangioma is still not understood. It has been suggested that growth factors and hormonal influences contribute to the abnormal cell proliferation. Cavernous liver hemangiomas are more commonly diagnosed in women who have been pregnant. As a result of this, it is believed that estrogen levels may play a role in the incidence of liver cavernomas.
Genetic studies show that specific gene mutations or deletions are causes for the disease. The genes identified for cerebral cavernous hemangiomas, are CCM1, CCM2 and CCM3. The loss of function of these genes is believed to be responsible for cerebral cavernous malformations. Furthermore, it is also believed that a "second hit mutation" is necessary for the onset of the disease. This means that having a mutation in one of the two genes present on a chromosome is not enough to cause the cavernous malformation, but mutation of both alleles would cause the malformation. Additionally, research on hemangiomas in general has shown that loss of heterozygosity is common in tissue where hemangioma develops. This would confirm that more than a single allele mutation is needed for the abnormal cell proliferation. KRIT1 has been shown to act as a transcription factor in the development of arterial blood vessels in mice. CCM2 has overlapping structure with CCM1 and acts as a scaffolding protein when expressed. Both genes are involved with MAP3K3 and thus appear to be a part of the same pathway. pathways CCM2 has been shown to cause embryonic death in mice. Lastly, the CCM3 gene has been shown to have similar expression to CCM1 and CCM2, suggesting a link in its functionality. Currently, no experiments have determined its exact function. The lack of function of these genes in control of a proliferative signaling pathway would result in uncontrolled proliferation and the development of a tumor. In 2018, it was theorized that proliferation of endothelial cells with dysfunctional tight junctions, that are under increased endothelial stress from elevated venous pressure provides the pathophysiological basis for cavernous hemangioma development.
Diagnosis
Gradient-Echo T2WI magnetic resonance imaging is most sensitive method for diagnosing cavernous hemangiomas. MRI is such a powerful tool for diagnosis, it has led to an increase in diagnosis of cavernous hemangiomas since the technology's advent in the 1980s. The radiographic appearance is most commonly described as "popcorn" or "mulberry"-shaped. Computed tomography scanning is not a sensitive or specific method for diagnosing cavernous hemangiomas. Angiography is typically not necessary, unless it is required to rule out other diagnoses. Additionally, biopsies can be obtained from tumor tissue for examination under a microscope. It is essential to diagnose cavernous hemangioma because treatments for these lesions are less aggressive than that of cancerous tumors, such as angiosarcoma. However, since MRI appearance is practically pathognomonic, biopsy is rarely needed for verification.On ultrasound, cavernous haemangiomas in liver appeared as homogenous, hyperechoic lesions with posterior acoustic enhancement. On CT or MRI scans, it shows peripheral globular/nodular enhancement in the arterial phase, with portions of attenuation of enhancing areas. In the portal venous phase, it shows progressive centripetal enhancement. In delayed phase, it shows retention of contrast. It shows a high signal on T2 weighted images.
Treatment
Asymptomatic lesions may not require treatment but may need to be monitored for any change in the size. A change in size of lesions in the nose, lips, or eyelids can be treated with steroid drugs to slow its progress. Steroids can be taken orally or injected directly into the tumor. Applying pressure to the tumor can also be used to minimize swelling at the site of the hemangioma. A procedure that uses small particles to close off the blood supply is known as sclerotherapy. This allows for tumor shrinkage and less pain. It is possible for the tumor to regrow its blood supply after the procedure has been done. If the lesion caused by the cavernous hemangioma is destroying healthy tissue around it or if the patient is experiencing major symptoms, then surgery can be used to remove the cavernoma piecemeal. A common complication of the surgery is hemorrhage and the loss of blood. There is also the possibility of the hemangioma reoccurring after its removal. Additionally, the risk of a stroke or death is also possible.Treatments for cerebral cavernous hemangiomas include radiosurgery or microsurgery. The treatment approach depends on the site, size and symptoms present, as well as the history of hemorrhage from the lesion. Microsurgery is generally preferred if the cerebral cavernous hemangioma is superficial in the central nervous system, or the risk of damage to surrounding tissue from irradiation is too high. Additionally, a large hemorrhage with deterioration of the patient or intractable symptoms are further indications for microsurgical intervention. Gamma-knife radiation is the favored mechanism of radiosurgery. It provides a precise radiation dose to the cerebral cavernous hemangioma while relatively sparing the surrounding tissue. These treatment approaches for cavernous hemangiomas in other regions of the body have limited research.