Vascular malformation
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# Overview
Vascular malformation is a blood vessel abnormality. There are many types, but the most common is arteriovenous malformation. Clinical behavior and growth cycles vary widely and it may cause clinical and aesthetic problems.  International Society for the Study of Vascular Anomalies (ISSVA) has classified vascular malformation into simple malformation, combined malformation, those of major named vessels, and those associated with other anomalies. Simple malformation have been divided further into capillary malformation, venous malformation and lymphatic malformation.

# Classification
Abbreviations: CM:capillary malformation; VM:venous malformation; CVM:capillary venous malformation; LM:lymphatic malformation; CLM:capillary lymphatic malformation; AVM:arteriovenous malformation; CAVM:capillary arteriovenous malformation; LVM:lymphatic venous malformation; CLVM:capillary lymphatic venous malformation; CVAVM:capillary venous arteriovenous malformation; CLVAVM:capillary lymphatic venous arteriovenous malformation; AVF:arteriovenous fistula; CLOVES:congenital lipomatous overgrowth, vascular malformations, epidermal nevi, skeletal/scoliosis and spinal abnormalities; M-CM:macrocephaly-capillary malformation; MCAP:megalencephaly-capillary malformation-polymicrogyria; MICCAP:microcephaly-capillary malformation; CNS:central nervous system; DCMO:diffuse capillary malformation with overgrowth; CM-AVM:capillary malformation-arteriovenous malformation; CMTC:cutis marmorata telangiectatica congenita; HHT:hereditary hemorrhagic telangiectasia; GLA:generalized lymphatic anomaly; KLA:kaposiform lymphangiomatosis; VMCM:venous malformation cutaneo mucosal; GVM:glomuvenous malformation; CCM:cerebral cavernous malformation.
Adapted from International Society for the Study of Vascular Anomalies

# Simple Vascular Malformations
Simple Vascular Malformations are divided into:
- Capillary malformation
- Lymphatic malformation
- Venous malformation
- Arteriovenous malformation
- Arteriovenous fistula

# Combined Vascular Malformations
Abbreviations: CM:capillary malformation; VM:venous malformation; CVM:capillary venous malformation; LM:lymphatic malformation; CLM:capillary lymphatic malformation; AVM:arteriovenous malformation; CAVM:capillary arteriovenous malformation; LVM:lymphatic venous malformation; CLVM:capillary lymphatic venous malformation; CVAVM:capillary venous arteriovenous malformation; CLVAVM:capillary lymphatic venous arteriovenous malformation.

# Vascular Malformations of Major Named Vessels
Abbreviations: AVF:arteriovenous fistula.

# Vascular Malformations associated With other Anomalies
Abbreviations: CM:capillary malformation; VM:venous malformation; LM:lymphatic malformation; AVM:arteriovenous malformation; AVF:arteriovenous fistula; CLOVES:congenital lipomatous overgrowth, vascular malformations, epidermal nevi, skeletal/scoliosis and spinal abnormalities; M-CM:macrocephaly-capillary malformation; MCAP:megalencephaly-capillary malformation-polymicrogyria; MICCAP:microcephaly-capillary malformation.

## Klippel-Trenaunay syndrome
- First described by Klippel and Trenaunay in 1900, this congenital syndrome is characterized by presence of capillary malformations, venous malformations, and soft tissues and bone hypertrophy. Lymphatic malformations may or may not be present. Capillary malformations typically present in form of capillary hemangioma and can occur anywhere on the body while venous and lymphatic malformations, and soft tissue and bone hypertrophy usually involves the extremities.
- Clinical manifestations are unilateral in 85% of the cases and may include localized pain and discomfort, leg length discrepancy due to hemihypertrophy, developmental delay, limb abnormalities such as polydactyly, macrodactyly, syndactyly, thrombophlebitis, osteomyelitis, pathological fractures, heart failure, erysipelas, venous thrombosis due to malformations, pulmonary embolism, gastrointestinal bleeding due to venous overload in the internal iliac vein and ophthalmic abnormalities such as telangiectasia, orbital varix, strabismus, oculosympathetic palsy, Marcus-Gunn pupil, iris coloboma and heterochromia, cataracts, persistent fetal vasculature and varicosities.
- Etiology and pathogenesis have not been established yet. Some suggestions include PIK3CA mutations, polygenic inheritance, VG5Q mutation and obstruction of the venous system.
- Diagnosis can be made on clinical manifestations and can be confirmed by Doppler ultrasound and magnetic resonance angiography. Management depends on clinical manifestations.
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## Parkes Weber syndrome
- Characterized by a cutaneous flush with underlying multiple micro-AVFs (arteriovenous fistulas), in association with soft tissue and skeletal hypertrophy of the affected limb. Clinical Presentation enlarged arteries and veins, capillary or venous malformations, cutaneous blush, arteriovenous fistulas, and enlargement of limb.
- Mutation in the RASA1 gene has been found to be associated with this syndrome.
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## Servelle-Martorell syndrome
- Also called phlebectatic osteohypoplastic angiodysplasia, this rare syndrome is characterized by venous malformations such as abnormal location of vein, partial or complete absence of valves, and/or venous hypoplasia or aplasia and undergrowth of bone. These abnormalities may also be associated with limb hypertrophy and arterial malformations.
- Clinical manifestations may include cutaneous compressible lesions due to malformations, cellulitis, lesion limb shortening, joint and soft tissue pain and swelling, tortuous limbs, reduced muscle mass, venous thrombosis, consumption coagulopathy, pathological fractures and bone tenderness.
- Combination of clinical and radiological findings is used to form the diagnosis, MRI can assess the involvement and extent of lesions. Treatment is mainly conservative with surgery being used in some cases to excise and/or correct malformations.

## Sturge-Weber syndrome
- Congenital syndrome characterized by capillary malformations involving face and laptomeninges and eye abnormalities. There may also be bone and/or overgrowth.
- Clinical manifestations may include seizures, port-wine stain on the forehead and upper eyelid of one side of the face,  muscle weakness, developmental delays and mental retardation, glaucoma, and buphthalmos.
- Associated with mutations in GNAQ gene that encodes for members of G protein family.
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## Maffucci syndrome
- A rare disorder characterized by presence of venous malformations associated with multiple enchondromas, benign cartilage-forming tumors, and multiple soft tissue hemangiomas, and lymphangiomas. These benign tumors have tendency to undergo malignant transformation in Maffucci syndrome. People with Maffucci syndrome are also at increased risk of developing other malignant tumors such as glioma, glioblastoma, acute myeloid leukemia, intrahepatic cholangiocarcinomas, hepatocellular carcinoma, pancreatic, and breast malignancies. Clinical manifestations depend on the coexisting lesions.
- Mutations in isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2), enzymes involved in metabolism of isocitrate and -ketoglutarate, and TP53, a cell-cycle regulator, have been found in tumors in Maffucci syndrome.
- Patients should be evaluated to check for malignant transformation. Some recommend CT scans and PET scans at regular intervals.
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## CLOVES syndrome
- CLOVES is an acronym for congenital lipomatous overgrowth, vascular malformations, epidermal nevi, skeletal and spinal anomalies. Vascular malformations in this syndrome include venous, capillary and lymphatic malformations with or without combined arteriovenous malformations. Pulmonary thromboembolism and respiratory failure are the cause of mortality in majority of the patients. Lipomatous and vascular abnormalities are often segmental and asymmetric in distribution and present typically on chest and abdominal wall.
- Clinical and imaging findings may include swellings due to lipomatous growths, skin discoloration, port wine stain, bilateral epidermal nevi,leg length discrepancy, developmental limb anomalies such as increased gap between the first and second toes, hemorrhage, seizures, ascites, pleural effusions, hypotension, bilateral multicystic venous and lymphatic malformations, chest wall venous dilatation, multiple congenital hemangiomas, asymmetric septal hypertrophy, renal hypoplasia, dislocated knees, scoliosis, and neural tube defect.
- Activating mutations in PICK3CA gene that encodes part of PI3K has been thought to be associated with this syndrome. These mutations may help enable the cells to grow independent of growth factors.
- This syndrome can be detected prenatally and its manifestations have been identified on prenatal ultrasound and fetal MRI. Treatment options include supportive management, surgical debulking and scletherapy but treatment is often complicated by severity of the disease resulting in anemia, coagulopathy and poor wound healing.

## Proteus syndrome
- Congenital syndrome characterized by asymmetric overgrowth of multiple tissues in limbs, hamartomas and vascular lesions such as capillary malformations, venous malformations, lymphatic malformations. Cerebriform connective tissue nevi, a pathognomonic lesion if present alone, are helpful in diagnosing Proteus syndrome. It may affect multiple organs such as eyes, spleen, liver, thymus, intestine, and lungs, and may cause facial dysmorphia. Some benign and malignant neoplasms such as testicular papillary adenocarcinoma and mesothelioma.
- Clinical manifestations and findings may include hemihypertrophy, asymmetry of the limbs, scoliosis, subcutaneous tumors, soft tissues tumors such as lipoma, limb abnormalities such as macrodactyly, hyperpigmented lesions on skin, verrucous epidermal nevi, lung diseases, pulmonary embolism, venous thrombosis,  glaucoma, strabismus, nystagmus, pseudopapileudema, cardiac defects such as ARVC, healed myocardial infarctions, cardiomyopathies, cardiac lipomas, and central nervous system findings. These findings may be detected prenatally or at birth but majority of the patients present after 6 months of birth.
- Somatic mutations in AKT1 gene that encodes proteins functioning in AKT/PI3K signaling pathway has been proposed to be the cause of this syndrome. This pathway functions in cell growth, differentiation, and survival.
- Diagnosis is based on clinical and radiological findings and must meet general and specific criteria. Management consists of clinical and psychological assistance. This may include orthopedic consultation to stop or delay bone growth, physical rehabilitation, surgical correction of deformities such as scoliosis, dermatology consultation fro skin lesions, workup and followup for vein thrombosis and pulmonary embolism, intervention for developmental delay, and evaluation for associated neoplasms at regular intervals.
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## Bannayan-Riley-Ruvalcaba syndrome
- An overgrowth syndrome characterized by vascular malformations, macrocephaly, multiple benign neoplasm and pigmented lesions on the skin. Speckled pigmented macules on genitalia are one of the most significant diagnostic characteristics. People with this syndrome may have increased risk of developing neoplasms in many organs such as thyroid, breasts, and female genital tract although it has not been confirmed.
- Typical manifestations and findings may include  multiple lipomas, hemangiomas, intestinal hamartomatous polyposis, vascular malformations such as arteriovenous malformations and capillary malformations, developmental delay, macrocephaly (>97 percentile), penile pigmented macules, thyroid abnormalities such as multinodular goiter, thyroid adenoma, differentiated non-medullary thyroid cancer and Hashimotos thyroiditis, high-arched palate, protuberant frontal bone, hypertelorism, strabismus, macrosomia, hypotonia, joint hyperextensibility, hypoglycemia, convulsions, cafe-au-lait spots, prominent forehead, malar hypoplasia and  micrognathia.
- Mutations in PTEN gene have been thought to be the cause. This gene encodes an enzyme that acts as tumor suppressor by stopping cell division and inducing apoptosis. Both autosomal-dominant transmission and sporadic occurrence have been reported.
- Diagnosis is based on clinical findings, the most important of these findings being penile pigmented maculae, hamartomatous intestinal polyposis and macrocephaly. Management consists of psycho-social counseling and treatment of manifestations such as surgical and dermatological interventions, spinal stimulation for intractable gastrointestinal pain and screening for malignancies associated with PTEN mutations such as annual thyroid ultrasound and mammography.
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## CLAPO syndrome
- CLAPO syndrome, a syndrome diagnosed in 6 patients, is an acronym for capillary malformation of the lower lip, lymphatic malformations of the face and neck, asymmetry, and partial or generalized overgrowth. Manifestations may include cutaneous lesions on head and neck and asymmetrical overgrowth.
- Somatic activating  PIK3CA mutations have been found in patients with CLAPO syndrome. This gene encodes proteins that function in cell-signaling pathways.