Vascular anomaliesДенис Овечкін

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ЗмістVascular anomalies

VASCULAR TUMORSInfantile HemangiomaCongenital HemangiomaIntramuscular hemangioma

VASCULAR MALFORMATIONSCapillary MalformationLymphatic MalformationVenous MalformationArteriovenous malformationsArteriovenous Fistula

Vascular anomalies 3

Vascular anomaliesVascular Tumors

Infantile HemangiomaCongenital HemangiomaIntramuscular hemangioma

Vascular MalformationsCapillary MalformationLymphatic MalformationVenous MalformationArteriovenous malformationsArteriovenous Fistula

Vascular anomalies

Vascular anomalies are disorders of the endothelium that usually present during childhood. These lesionsaffect all parts of the vasculature: capillaries, veins, arteries, or lymphatics.

Although nearly always benign, vascular anomalies may involve any location and are often locallydestructive. In addition to severe disfigurement, local complications include obstruction, bleeding, boneloss, and pain. Systemic sequelae can include thrombocytopenia, pulmonary embolism, congestive heartfailure, and even death.

A biologic classification of vascular anomalies based on physical findings, natural history, and cellularcharacteristics has clarified the differences between the different types of vascular anomalies. Inparticular, vascular anomalies are broadly divided into two groups:

· Tumors – are characterized by endothelial cell proliferation (endothelial

hyperplasia).· Malformations – arise due to vascular dysmorphogenesis and have normal

endothelial cell turnover. What is the difference between a vascular tumor and a vascular malformation? –

Vascular tumors can regress or persist depending on their type. Vascular malformations never regress,they persist throughout life. Most of them have commensurate growth during childhood, and someworsen over time if not treated [11, 14, 43].

The suffix, -angioma (as in hemangioma), should be reserved for benign vascular tumors - whether

congenital or acquired or monoclonal or polyclonal - that arise by cellular hyperplasia.Alternatively, the term, malformation, should designate errors in vascular morphogenesis that

usually (but not always) become clinically evident at birth and exhibit proportionate growth and littleendothelial mitotic activity (eg, venous malformation).

Characteristics of Common Vascular Anomalies

Vascular Tumor / InfantileHemangioma

Vascular Malformations

ProliferativeFemale to male ratio 3:130% visible at birth70% become apparentduring first few weeks oflifeRapid postnatal growthfollowed by slow involutionEndothelial cellproliferationIncreased mast cellsNo coagulationabnormalitiesHigh percentage respond

Congenital abnormality withproportional growthNo gender predilectionMay expand secondary tosepsis, trauma, or hormonalchangesNormal endothelial cellturnoverNormal mast cell countDo not involuteLocalized consumptivecoagulopathy possibleLow-flow: phleboliths, ectaticchannelsHigh-flow: enlarged, tortuousvessels with arteriovenous

Vascular anomalies 4

dramatically tocorticosteroid treatment in2 to 3 weeksImmunopositive forbiologic markers (includingGLUT1)

vessels with arteriovenousshuntingNo response tocorticosteroids orantiangiogenic agentsImmunonegative forhemangioma biologicmarkers

Previously vascular anomalies were divided into tumors and malformations, based on presence orabsence of endothelial mitotic activity. Nowadays presence of endothelial mitotic activity alone is notsufficient as a single factor to separate tumors from malformations, because there are secondaryeffects, such as ischemia and turbulence, which may stimulate mitotic activity.

The International Society for the Study of Vascular Anomalies (ISSVA) classification of

vascular anomaliesVascular tumors

Infantile hemangiomasCongenital hemangiomas (RICH and NICH)Tufted angioma (with or without Kasabach-Merrittsyndrome)Kaposiform hemangioendothelioma (with or withoutKasabach-Merritt syndrome)Spindle cell hemangioendotheliomaOther, rare hemangioendotheliomas (epithelioid,composite, retiform, polymorphous, Dabska tumor,lymphangioendotheliomatosis, etc.)Dermatologic acquired vascular tumors (pyogenicgranuloma, targetoid hemangioma, glomeruloidhemangioma, microvenular hemangioma, etc.)

Vascular malformationsSlow-flow vascular malformations:

Capillary malformation (CM)Port-wine stainTelangiectasiaAngiokeratoma

Venous malformation (VM)

- Common sporadic VM- Bean syndrome- Familial cutaneous and mucosal venous malformation

(VMCM)- Glomuvenous malformation (GVM) (glomangioma)- Maffucci syndrome

Lymphatic malformation (LM)

Fast-flow vascular malformations:

Arterial malformation (AM)Arteriovenous fistula (AVF)Arteriovenous malformation (AVM)

Complex-combined vascular malformations:CVM, CLM, LVM, CLVM, AVM-LM, CM-AVM

C – capillary; V – venous; L – lymphatic; AV – arteriovenous; M –malformation. RICH – rapidly involuting congenital hemangioma;NICH – noninvoluting congenital hemangioma.

VASCULAR TUMORS

Vascular anomalies 5

Infantile HemangiomaHemangioma is a benign, and usually a self-involuting tumor of the endothelial cells (endothelium) thatline blood vessels and is characterised by increased number of normal or abnormal vessels filled withblood.

Hemangioma is the most common neoplasm of infancy. Capillary or strawberry hemangioma haspreviously been used to describe hemangioma involving the dermis, which appeared red. Hemangiomasdeep to the dermis may appear bluish and have been referred to as cavernous hemangioma. The termscapillary and cavernous also have been used to describe CM and VM, respectively.

NB: The terms capillary, strawberry, and cavernous confuse diagnosis and should not be used. Infantile hemangioma (IH) occurs in approximately 4% of white-skinned infants. The incidence is lower

in dark-skinned babies. There is a female-to-male preponderance of 3:1. Extremely-low-birth-weightinfants (<1000 g) have the highest incidence of IHs, approaching 23% [14, 43]. Additional risk factorsinclude advanced maternal age, multiple gestations, and placental abnormalities.

IHs most often occur as a single cutaneous lesion (80%) with a predilection for the head and neck

(60%), trunk (25%), and extremities (20%) (Image 9.2). Multiple tumors are present in up to 20% ofpatients and, when present, may signal involvement of extracutaneous organs such as the liver orgastrointestinal (GI) tract.

Median age of onset is 1 to 2 weeks. A premonitory cutaneous mark such as a pale spot or faint

macular stain is present at birth in 30% to 50% of cases. The majority (90%) of IHs are small, localizedlesions that do not involve aesthetically or functionally vital structures. Endangering or life-threateningIHs are rare.

Image 9.2Infantile hemangioma.Cervicofacial and

subglottic IHs can be life-threatening due to airwayobstruction.

Hemangiomas have unique growth stages:

1. a proliferating phase until 1 year of age,2. an involuting phase from 1 to 7 years of age,3. and finally an involuted phase after 7 years of age.

By 5 years of age, 50% of tumors have completed involution, which increases to 70% at 7 years of age

[11, 14, 43]. There is often continued gradual regression of the color and bulk of the tumor until 10 to 12years of age. At the end of involution, 50% of patients have nearly normal skin in the area of the priorlesion. Large tumors can leave lax, redundant skin and/or a fibrofatty residuum. Previously ulceratedlesions can leave permanently damaged skin, scars, and discoloration.

Etiology and PathogenesisThe cause of hemangioma is currently unknown.A hemangioma consists of an abnormally dense group of extra blood vessels. It's not clear what

causes the blood vessels to group together, although there may be a hereditary component involved.Clinical CharacteristicsAlthough hemangiomas usually affect the skin, isolated visceral lesions also occur.The occurrence of multiple IHs is called hemangiomatosis. Occult visceral lesions may be present

when multiple cutaneous IHs (usually five or more) are found. The liver is the most frequently involvedlocation [43].

Diagnosis90% of hemangiomas may be diagnosed by history and physical exam. Radiographic studies can aid in the diagnosis in the 10% of patients whose diagnosis is still in

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question after the history and physical exam.¤ Ultrasonography is an easy and cost-effective way of differentiating hemangioma from slow-

flow vascular anomalies.¤ Radionucide scanning with technetium Tc 99m-tagged red blood cells may be used to locate

multiple hemangiomas in the central nervous system or gastrointestinal tract.¤ MRI is the radiologic modality of choice for differentiating vascular anomalies.

ImmunohistochemistryIH has a unique and complex endothelial phenotype shared only by placental capillaries that includes

expression of GLUT-1 (Glucose transporter 1), Lewis Y antigen, FcgRII, CD15, CCR6, IDO, and IGF2; GLUT-1 immunostains are useful for diagnostic confirmation.

NB: Endothelial celles in RICH (rapidly involuting congenital hemangioma) and other vascular tumorsor malformations do not express GLUT-1 protein.

Associated Structural AbnormalitiesCongenital abnormalities are rarely associated with IH, but larger hemangiomas and those

encountered in the midline merit attention.A subgroup of patients with IH exhibits associated structural anomalies of the brain (e.g., posterior

fossa abnormalities), cerebral vasculature (e.g., hypoplasia or absent carotid and vertebral vessels,aneurysms), eye (e.g., cataracts and optic nerve hypoplasia), aorta (e.g., coarctation), and chest walldefects (e.g., sternal clefts) in the neurocutaneous disorder called PHACES syndrome (Posterior fossamalformations, Hemangioma, Arterial anomalies, Cardiac defects, Eye anomalies, and Sternal defects).

Anorectal and genitourinary anomalies can occur with IH of the pelvis or perineum, sometimes as parto f PELVIS syndrome (Pelvic hemangioma, External genital malformations, Lipomeningocele,Vesicorenal, Imperforate anus, Skin tags).

TreatmentObservationThe majority of IHs require no specific treatment other than observation [14, 43, 45]. Even if the

proper decision is not to intervene, this does not mean that nothing should be done. Regularly scheduledfollow-up is imperative. Parents should be reassured by showing them photographs of the tumor in itsproliferative, involuting, and involuted phases.

Patients are followed closely through the proliferative phase of growth. In case of Endangering Complications10% of hemangiomas cause significant deformity or severe complications. Most complications occur

with hemangiomas located in the head and neck.Sublottic hemangioma may obstruct the airway, whereas ulcerated lesions may destroy the eyelid,

ear, nose, or lip. Periorbital hemangioma can block the visual axis or distort the cornea causingamblyopia. Gastrointestinal hemangioma may cause bleeding that requires transfusions.

Large hemangiomas, most commonly involving the liver, can cause high-output congestive heartfailure or hypothyroidism. Hypothyroidism results from the expression of a deiodinase by thehemangioma that cleaves iodine from thyroid hormone. Consequently, thyroid function should beevaluated in patients with a large hemangioma. Massive intravenous thyroid replacement may benecessary to avoid mental retardation until the hemangioma regresses.

Local wound treatment is indicated for the 5% of cutaneous hemangiomas that cause skin ulceration.

Ulceration is more common on the lips, anogenital region, and parotid region.Local treatment includes application of hydrated petrolatum and viscous lidocaine, topical antibiotic, or

hydrocolloid dressing. Eschars should be debrided and treated with wet-to-dry dressing changes.Flashlamp pulsed-dye laser may aid healing when two applications are given 4 to 6 weeks apart.Resection of the ulcerated tumor may be performed when the defect can be closed primarily, and the

resulting scar would not be worse than if the lesion were removed during involution. Excision is mostcommonly performed for small, well-localized lesions on the scalp, chest, or extremity, but not for faciallesions.

Pharmacotherapyu Systemic pharmacologic intervention may be necessary for endangering, ulcerating, problematic, or

life-threatening IHs.Until recently, systemic corticosteroids were the first-line medical therapy for most complicated

hemangiomas. But now the current first-line treatment is Propranolol, a nonselective beta blocker,systemically and topically.

Propranolol, a nonselective beta blocker, is being used with increasing frequency for the treatment

of IHs. Early reports suggest that propranolol may be as efficacious as corticosteroids for the treatmentof problematic IHs [17, 43]. The mechanism of action for propranolol is unknown; theories includevasoconstriction of the tumor vasculature or downregulation of angiogenic proteins.

Corticosteroids inhibit the vasculogenic potential of hemangioma-derived stem cells, as well as the

expression of vascular endothelial growth factor. Prednisone or prednisolone is administered in themorning at 2 to 3 mg/kg/day for 2 weeks. Initial improvement in color and tension is usually evident in the

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first 1 to 2 weeks. If the IH stabilizes, the dosage is tapered every 2 to 4 weeks with a goal ofdiscontinuation by 10 to 11 months of age. The overall response rate is 80% to 90% [14].

Live vaccines (e.g., polio, measles, mumps, rubella, varicella) should not be administered duringcorticosteroid treatment.

u Intralesional injection of corticosteroid for well-localized tumors of the nasal tip, cheek, lip, or eyelid is

used to minimize deformity. There are reports of retinal artery occlusion and eyelid necrosis, presumablyfrom embolization of colloidal particles. Compression at the periphery of the lesion will help minimize thisrisk. Triamcinolone (25 mg/mL) is injected slowly at a low pressure with a 3-mL syringe and 25-gaugeneedle. The dosage is 3 to 5 mg/kg per injection. Additional injections can be done at 6- to 8-weekintervals; usually, three to five are necessary. Response rates are similar to that of oral corticosteroid[14].

Embolic TherapyLarge hemangiomas may cause high-output congestive heart failure. These lesions most commonly

arise in the liver. Rarely, embolization of the feeding artery may be indicated for the initial control of heartfailure while the therapeutic effects of systemic drug therapy are pending, or when drug therapy isunsuccessful. Only a subset of liver hemangiomas with large vascular shunts cause high cardiac output.Embolization has little or no role in hepatic hemangioma without heart failure [14].

Laser TherapyFlashlamp pulsed-dye laser is not beneficial for nascent or proliferating hemangiomas. It penetrates

only the most superficial portion of the dermis (0.75 to 1.2 mm) and leaves the majority of the lesionuntreated, causing some lightening [43, 45].

Moreover, a superficial IH is often the tumor that requires no treatment and involutes without a trace.The flashlamp pulsed-dye laser has not been shown to decrease hemangioma bulk or accelerate

involution.Laser treatment can cause hypopigmentation and increase scarring by causing ulceration and partial-

thickness skin loss.The flashlamp pulsed-dye laser is indicated, however, during the involuting/involuted phase to treat

residual telangiectasias. One indication for laser treatment during the proliferative phase is for excision ofa subglottic hemangioma with a carbon dioxide laser [14, 43, 45].

Surgical TherapyExcision of proliferating hemangioma is generally not indicated; rather, the outcome is improved when

surgery is deferred until after the tumor has involuted (4-7 years) [14, 43, 45]. However, well-localized or pedunculated lesions that are ulcerated or bleeding may be excised if the

resulting scar is no worse than would be expected after excision during involution or if the scar may behidden.

Large tumor size and the presence of ulceration increase the likelihood that later reconstruction willbe necessary.

Occasionally, focal gastrointestinal lesions that continue to bleed despite pharmacotherapy can beremoved by endoscopic ligation or bowel resection.

Ultimately, 55% of children will have residual skin changes after hemangioma involution, including

excess skin, fibrofatty tissue, and hypo- or hyperpigmentation with telangiectasias. Because childrenbecome aware of their body differences by 4 years of age, removal of these residual lesions should beconsidered to avoid the development of low self-esteem [43].

Congenital HemangiomaCongenital hemangiomas differ from infantile hemangiomas in that they are fully developed at birth andtest negative for the immunohistochemical marker GLUT-1 (Image 9.3). Two main types of congenitalhemangiomas have been described: (1) noninvoluting congenital hemangioma (NICH), whichpresent at birth and demonstrate proportional growth without regression and (2) rapidly involutingcongenital hemangioma (RICH), which present at birth and regress completely within 2 years.

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Image 9.3Congenital

hemangioma.Most lesions are

solitary. There is nogender bias. Theselesions are furtherdistinguished from IHby staining negativelyfor GLUT-1.

RICHs undergo involution early, often beginning before birth. Involution is complete between 6 and 14months of age. RICHs commonly affect the head/neck and extremities. On physical examination, thelesions are raised, firm, pink to violaceous with central depression or ulceration and a surrounding palerim. After involution, the residual area often appears deflated and is not accompanied by the usual fattyresiduum of IH. Prenatal detection is possible because RICHs arise in utero.

NICHs present as bossed, round-to-ovoid shape lesions in shades of pink to purple. The averagediameter is 5 cm. There may be overlying coarse telangiectasia. NICHs most commonly affect thehead/neck (43%) followed by the limbs (38%) and trunk (19%). As the name implies, NICHs do notundergo involution and persist essentially unchanged. Although they are tumors histologically, the staticbehavior of NICHs resembles that of a malformation.

RICHs and NICHs are fast-flow by Doppler evaluation. RICHs exhibit large flow voids near the surfaceand have areas that enhance inhomogenously on MRI. The differential diagnosis of congenitalhemangioma includes infantile fibrosarcoma.

NB: Medical treatment is similar to that of infantile hemangiomas!Kaposiform Hemangioendothelioma and Tufted Angioma (with or without Kasabach-Merritt syndrome)Kasabach–Merritt syndrome (KMS), also known as Hemangioma with thrombocytopenia is a rare

disease, usually of infants, in which a vascular tumor leads to decreased platelet counts and sometimesother bleeding problems, which can be life-threatening. It is also known as hemangiomathrombocytopenia syndrome.

Kasabach-Merritt phenomenon occurs with more aggressive and invasive vascular tumors such as

kaposiform hemangioendothelioma (KHE), kaposiform lymphatic anomaly (KLA), and tufted angioma(TA).

These tumors are biologically distinct from infantile hemangioma. KHE and TA share several features

and are more invasive than hemangioma. They are usually present at birth, but can appear postnatally.They are solitary and, unlike hemangioma, affect males and females equally. They most commonly occuron the trunk, shoulder, thigh, or retroperitoneum. The skin overlying KHE appears purple, tense, andshiny (Image 9.4). In addition, petechiae and ecchymosis surround the tumor.

Generalized petechiae may be apparent due to profound thrombocytopenia (< 10,000 platelets/µL).

Infants with Kasabach-Merritt phenomenon are at risk for intracranial, pleural, pulmonary, peritoneal, andGI hemorrhage.

TA appears as an erythematous macule or plaque. A hallmark of these tumors is that they are

associated with Kasabach-Merritt syndrome, which is the associated finding of profoundthrombocytopenia, petechiae, and bleeding, with large vascular lesions.

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A BImage 9.4 A – Kaposiform hemangioendothelioma;

B – Tufted angioma.

If the diagnosis cannot be established based on history and exam, MRI can differentiate KHE fromhemangioma. Like proliferating hemangioma, KHE shows enhancement and large vessels on T2-weighted images. However, KHE has poorly defined margins, small vessels, and invasion of adjacenttissues.

Histologically, KHE shows infiltrating sheets or nodules of endothelial cells lining capillaries. In addition,dilated lymphatics are present and filled with hemosiderin and red blood cell fragments. TA may bedistinguished from KHE because TA is characterized by small tufts of capillaries (cannonballs) in themiddle to lower third of the dermis.

KHE and TA continue to proliferate into early childhood and then partially regress by midchildhood.These lesions usually persist long term, although they are commonly asymptomatic. Systemicpropranolol (nonselective beta blocker) and corticosteroids are the first-line therapy [17, 43].However, only 50% of these lesions respond to pharmacologic treatment and mortality rates are high(20% to 30%) [14]. Platelet transfusions should be avoided unless there is active bleeding or a plannedsurgical procedure because exogenous platelets are trapped in the lesion causing swelling. In addition,heparin should not be administered because it stimulates tumor growth and aggravates platelettrapping, worsening bleeding.

Other treatment alternatives for patients with KHE are transcatheter embolization and surgicalexcision.

Intramuscular hemangiomaIntramuscular hemangioma is a rare condition; it differs from infantile hemangioma simply because itoccurs in patients older than children (Image 9.4).

Image 9.4 T1 and T2 MRI images of intramuscular hemangioma ofthe leg.

Most cases described as "intramuscular hemangioma" in the literature actually represent soft tissuevenous malformations. This confusion cause inappropriate referrals, imaging studies and eventherapeutic interventions in significant number of patients. Therefore, it is important to distinguish thesetwo conditions (intramuscular hemangioma versus soft tissue venous malformation).

Intramuscular hemangioma can be seen in any age, commonly diagnosed in early adulthood. In

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contrast to venous malformations, intramuscular hemangiomas have arterial feeders and in contrast toAVMs, these vascular birthmarks do not demonstrate arteriovenous shunting.

TherapyObservation is appropriate for asymptomatic or mildly symptomatic hemangiomas of skeletal muscle

and bone. If symptoms cannot be managed adequately by activity modification and nonnarcoticanalgesics, further treatment may be considered. Embolization may be used to provide symptomaticrelief of intramuscular hemangiomas.

When surgical excision is planned, embolization also may be used preoperatively to decrease

intraoperative blood loss and postoperative recurrence. Complete resection is not always possible; whenincompletely resected, hemangiomas nearly always recur.

VASCULAR MALFORMATIONS

Capillary MalformationCapillary malformation (CM) is the proper name for "port-wine stain." These lesions consist of dilatedcapillary sized vessels in the superficial dermis with a paucity of normal nerve fibers. The lesion darkenswith age due to vessel dilatation. CM may be confused with nevus flammeus neonatorum, which occursin 50% of whites and is also known as “angel kiss” (on the forehead) or “stork bite” (on the nuchal area).Nevus flammeus neonatorum is due to a minor transient dilatation of dermal vessels that fades withage, whereas a CM does not (Image 9.5).

A

BImage 9.5 A – Capillary malformation;

B – Nevus flammeus neonatorum ("stork bite"). CMs affect 0,3% of infants with an equal sex distribution. Most CMs are sporadic, but some are inheritedin an autosomal dominant pattern. They are present at birth and appear as flat, pink-red, cutaneouspatches.

It may occur in any location and over time darkens and develops fibrovascular overgrowth.CM is also a common component of several combined VMs. TreatmentThe mainstay of treatment for CM is the flashlamp pulsed-dye laser (585 nm) [43, 45]. This laser

causes selective photothermolysis of CM via the chromophore oxyhemoglobin. The pulsed-dye laserdoes not penetrate more than 1.2 mm and results in lightening of the lesion in 70% of patients. Multiplesessions are often required.

Lymphatic MalformationLymphatic malformations (LMs) are frequently called "lymphangiomas," erroneously suggesting aproliferative tendency. LMs of the neck and axilla may be due to failure of lymphatic sacs to

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communicate with the central venous system. Sequestration of lymphatic buds may account forperipheral lesions.

LM is most commonly located in the head, neck, axilla, and mediastinum, and may be localized oraffect entire organ systems.

LMs are classified as microcystic, macrocystic, or combined macrocystic and microcystic lesions. LMs are usually apparent at birth and tend to occur in areas of major lymphatic channels, especially

the cervical and axillary locations (Image 9.6). They can be found in all tissues or organ systems with theexception of the central nervous system. LMs most commonly appear as ballottable masses with normaloverlying skin, although a blue hue may result if large underlying cysts are present.

Histologically, LMs appear as thin-walled vascular channels lined by lymphatic endothelial cells, whichare immunopositive for podoplanin (D2-40) and LYVE-1. The lumens may be empty or filled with aproteinaceous fluid containing macrophages and lymphocytes [14].

AB

Image 9.6 A – Cervical lymphatic malformation; B – MRI of LM lesions.

LM may be noted on prenatal ultrasound during the last trimester. Occasionally, LM presents in latechildhood or adulthood after bleeding or infection [14].

DiagnosisThe differential diagnosis of LM includes hemangioma, VM, rhabdomyosarcoma, fibrosarcoma, and

lymphoma. Most LM may be diagnosed by history and physical exam, with confirmation by MRI. Histologicconfirmation is rarely necessary. Ultrasound is effective for diagnosis macrocystic LM. However, MRI withgadolinium is the most sensitive study to delineate the extent of lymphatic malformation and type ofcysts.

ComplicationsBleeding and infection are the two most common complications of LM. Intralesional bleeding occurs in

35% of cervicofacial LM, whereas infection has been cited to occur in 71% of cervicofacial LMs [14, 43]. TreatmentLMs may be treated with sclerotherapy, surgical resection, or both.Sclerotherapy works well for macrocystic LMs and in many cases may render lesions undetectable.

Common sclerosant include pure ethanol, sodium tetradecyl sulfate, and doxycycline. Multiple punctures,aspirations, and injections are often performed. Ultrasound guidance is useful.

Microcystic LM is less responsive to sclerotherapy. Excision is indicated for patients with symptomaticmicrocystic lesion or problematic microcystic LM that fails sclerotherapy.

Venous MalformationVenous malformations (VMs) are slow-flow lesions that have incorrectly been referred to as “cavernoushemangiomas” in the past. They may be seen at birth or become apparent later depending on location.VMs are most common in the skin and soft tissues but can be located anywhere in the body.

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Microscopic FeaturesVMs are characterized by abnormal collections of veins that are superficial or deep, diffuse or

localized, and solitary or multiple. Component veins vary with regard to luminal size and wall thicknessboth between and within individual lesions. The lining endothelial cells are positive for CD31, vWF, andCD34 and are negative for GLUT1 and other IH-associated markers.

Clinical PresentationVM is present at birth, but may not become clinically evident until later in life. Although most VMs are

located in the skin or subcutaneous tissue, VM also may be located in other organs. They are bluish andcompressible, and may be localized, extensive, solitary, or multiple (Image 9.7 and 9.8).

The lesions are mostly superficial and occur as multiple blue to deep-purple nodules or confluent,cobblestone-appearing plaques frequently on the trunk or extremities. They are caused by loss-of-function mutations in glomulin, which derails vascular smooth muscle cell differentiation [14].

Image 9.7 Venous malformations and Lymphatic malformations

VM expands slowly and usually grows proportionately with the child. Puberty can exacerbate thegrowth of VM.

DiagnosisDiagnosis can be made by history and physical exam.Imaging modalities useful for the diagnosis of VM include ultrasonography, MRI, and venography. MRI is

the most informative.

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Image 9.8 Venous malformations.

TreatmentNo known systemic pharmacologic agents induced evolution of vascular malformations, and therefore

they are not used for VMs.Conservative treatment for symptomatic VM includes low-dose aspirin to minimize painful

phlebothromboses and support stockings for extremity VM.Like LM, the mainstays of treatment for VM causing disfigurement, pain, or functional problems is

sclerotherapy and surgical resection. Sclerosing agents include doxycycline, 100% ethanol, sodiumtetradecyl sulfate, and OK-432 (killed group A S. pyogenes) [14, 43].

As with LM, VM tends to recur after sclerotherapy because of recanalization. As a result, multiple

injections are often required. Local complications of sclerotherapy include skin necrosis or local nervedamage. Systemic complications include hemolysis, sudden pulmonary hypertension, and cardiac andrenal toxicities.

Although small, well-localized lesions may be excised primarily, larger lesions should be reduced bysclerotherapy prior to excision. Large, soft-tissue VM often requires staged excision.

Gastrointestinal lesions causing anemia may be excised or sclerosed endoscopically. Multifocal bowellesions of the blue rubber bleb nevus syndrome may be individually resected, although hundreds oflesions may be found and operative procedures may be extremely lengthy. Bowel resections should beperformed only in areas with a high density of VM.

Otherwise, multiple enterotomies can be made to remove lesions through a single enterotomy site byintussusception of adjacent bowel.

Colorectal lesions may be controlled by sclerotherapy. If this fails, colectomy, mucosectomy, and pull-through may be performed.

Arteriovenous malformationsArteriovenous malformations (AVMs) are fast-flow malformations characterized by abnormal collectionsof arteries and veins that directly communicate (shunts), thus bypassing the high-resistance capillarybed (Image 9.9).

Like all vascular malformations, AVMs are the result of errors in vascular morphogenesis and are not

neoplastic in origin.The shunts comprise the epicenter of the AVM, called the nidus. Intracranial AVMs are more common

than extracranial AVMs. Areas affected by extracranial AVMs in decreasing frequency are the head and neck, limbs, trunk, and

viscera. AVMs may be apparent at birth but are often misdiagnosed initially as a capillary malformationor infantile hemangioma due to pink staining in the overlying skin.

Although arteriovenous malformations are present in neonates at birth, they often suddenly become

obvious when the patient is older because of various stimuli such as trauma, pregnancy, or puberty. Clinical PresentationCommon symptoms include pain, overgrowth of the involved body part, changes related to decreased

blood flow (ischemia), bleeding, and heart failure. Bleeding is usually minor, but it may be very serious; ittypically occurs with dental work in patients with arteriovenous malformation of the dental arcade.Schobinger's staging (stages 1-4) is commonly used to describe the degree of progression (Table 9.2).

Table 9.2

Clinical Staging System for Arteriovenous MalformationStage Clinical Findings

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Image 9.10 MR Angiography

I (Quiescence) Pink-blue warm stain, shunting on Dopplerexamination

II (Expansion) Enlargement, pulsation, thrill, bruit, tenseveins

III (Destruction) Dystrophic skin changes, ulceration,bleeding, pain, or tissue necrosis

IV (Decompensation) Cardiac failure

Image 9.9 Arteriovenousmalformations.

As an AVM grows, it

can become moremasslike, causingulceration of theoverlying soft tissue,bleeding, pain, or heartfailure.

Lower-extremity AVMs

often develop curious,dry, brown-violaceous-colored plaques.

Diagnosis

· Doppler US - reveals high-flow low-resistance arteries and an arterialized waveform in the drainingveins.

· MRI - the anomaly is characterized by enlarged vascular channels associated with dilated feeding anddraining vessels. A discrete soft-tissue mass is typically absent.

· Angiography - today, most AVMs are studied with MR Angiography(Image 9.10) before embolization or surgery.

TherapyAngiographic embolization alone or in combination with surgical

excision is the mainstay of treatment [14, 43].Preoperative embolization decreases intraoperative blood loss but

does not decrease the extent of resection. Complete removal of thenidus and overlying soft tissue and skin is the goal; this will decreaserecurrence.

Treatment is usually delayed until symptoms indicative of stage IIIdevelop: tissue destruction, pain, bleeding, or ulceration [43, 45].

Arteriovenous FistulaAn arteriovenous fistula (AVF) is an abnormal connection orpassageway between an artery and a vein. It may be:

congenital;acquired due to pathologic process, such as trauma or erosion of an arterial aneurysm;

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acquired due to pathologic process, such as trauma or erosion of an arterial aneurysm;surgically created for hemodialysis treatments.

TreatmentCongenital AVF, if small, usually do not need treatment. Acquired fistulas can be treated by surgery.

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