Vascular malformations Notes


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Arteriovenous malformation


NOTES NOTES VASCULAR MALFORMATIONS GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Developmental malformations of the vascular system SIGNS & SYMPTOMS ▪ Usually asymptomatic ▪ Large malformations can cause obstruction /impair organ functions ▪ Diverts away high volume of blood → heart compensates → high-output heart failure DIAGNOSIS DIAGNOSTIC IMAGING ▪ Imaging studies usually not needed OTHER DIAGNOSTICS ▪ History ▪ Physical examination TREATMENT ▪ Generally no need for treatment unless formations bleed/cause other problems SURGERY ▪ Surgical/laser therapy considered for skin malformations Figure 22.1 Illustration depicting changing pressure between normal arteries and veins. OSMOSIS.ORG 145
ARTERIOVENOUS MALFORMATION PATHOLOGY & CAUSES ▪ Abnormal capillary bed formation between artery and vein ▪ Capillary bed does not form, leaving arteries connected directly to veins → tangling → nidus ▪ Arteriovenous fistula: single artery to single vein direct connection ▪ No capillaries → arteries, veins subjected to high pressures → arteries dilate → veins thicken (fibrosis) ▪ AVM expands over time → compresses surrounding tissues → decreases blood flow ▫ Can cause bruit (whooshing noise heard on auscultation) ▫ Noise can get loud enough that person with the bruit can hear it, causing psychological stress, hearing issues and sleep issues CAUSES ▪ Possibly congenital/genetic ▪ Osler–Weber–Rendu disease/hereditary hemorrhagic telangiectasia connected to AVM RISK FACTORS ▪ Biological male, 10–30 years old, genetic conditions (e.g. Osler-Weber-Rendu) COMPLICATIONS ▪ Ischemia at site, high output heart failure, rupture, haemorrhage SIGNS & SYMPTOMS ▪ Most are asymptomatic ▪ Depend upon location ▪ Presence of bruit on auscultation 146 OSMOSIS.ORG Brain ▪ Epilepsy, neurological deficits, abnormal sensations (numbness, tingling, pain) ▪ Sudden onset, severe headache indicates subarachnoid hemorrhage ▪ Difficulty with movement coordination, muscle weakness, paralysis, vertigo ▪ Apraxia (physical difficulties performing actions upon command, though command is understood) Lungs ▪ Asymptomatic 1/3 of time ▪ Dyspnea, cough, clubbing, cyanosis, hemoptysis, chest pain ▪ Platypnea (shortness of breath in upright position, relieved by lying down) ▪ Orthodeoxia (decrease in oxygen saturation by ≥ 2% when rising from lying down to standing) Spine ▪ Muscle weakness, paralysis Pediatric ▪ May present with ▫ Heart failure, macrocephaly, prominent scalp veins DIAGNOSIS DIAGNOSTIC IMAGING Angiography ▪ Functional anatomy of AVM ▫ Feeding arteries: stenosis ▫ Sharp twisting of veins (ectasia) ▫ Arterial and venous dilatation CT scan/MRI ▪ Anatomy of AVM ▫ Irregular/bulbous masses in brain/ brainstem
Chapter 22 Vascular Malformations OTHER DIAGNOSTICS ▪ Bruit TREATMENT ▪ Treat all arteriovenous malformations SURGERY Radiosurgery ▪ Radiation beams target AVM to close vessels Endovascular embolization ▪ Catheter placed to obstruct vessels Figure 22.2 CT scan of the head in the axial plane demonstrating an arteriovenous malformation in the left parietal lobe. CAVERNOUS HEMANGIOMA PATHOLOGY & CAUSES ▪ Benign tumor formed from tangle of unencapsulated, dilated, thin-walled blood vessels ▪ Spherical caverns form from dilatation of vessels separated by fibrous connective tissue ▪ Characteristic “mulberry” presentation TYPES RISK FACTORS ▪ Von Hippel–Lindau disease COMPLICATIONS ▪ ▪ ▪ ▪ Rupture → hemorrhage Obstructive jaundice, clotting disorders Intravascular thrombosis Dystrophic calcifications SIGNS & SYMPTOMS Cerebral cavernous malformations ▪ Usually asymptomatic Liver cavernous hemangioma ▪ Sometimes found in people with previous pregnancies → high estrogen levels thought to be a factor Brain ▪ Brain tissue compression → seizures, hemorrhages ▪ Stroke, speaking difficulties, memory/ attention difficulties ▪ Headaches, balance issues Ocular cavernous hemangioma CAUSES ▪ Genetic mutations ▫ CCM1, CCM2, CCM3 Liver ▪ Pain in right upper quadrant ▪ Gastrointestinal issues: nausea, vomiting, loss of appetite, early fullness after eating OSMOSIS.ORG 147
Eyes ▪ Double/decreased vision, proptosis DIAGNOSIS DIAGNOSTIC IMAGING MRI ▪ Seen as popcorn/mulberry shape → pathognomonic ▪ Hepatic cavernous hemangiomas best diagnosed with ▫ Ultrasound ▫ IV contrast CT scan ▪ Can be mistaken for metastatic tumors Figure 22.3 Abdominal CT scan in the axial plane showing a hemangioma of the liver. 148 OSMOSIS.ORG TREATMENT ▪ Monitoring usually sufficient MEDICATIONS ▪ Facial hemangioma growth slowed with steroids ▫ Administered orally/injected at site Sclerotherapy ▪ Close tumor’s blood supply → tumor shrinks SURGERY ▪ Prevent damage to healthy tissues Figure 22.4 A cavernous hemangioma from the liver, composed of large vascular spaces with thin walls. No normal liver is present.
Chapter 22 Vascular Malformations HEMANGIOMA PATHOLOGY & CAUSES ▪ Hemangioma/infantile hemangioma (IH): benign vascular skin tumor ▫ Originates from endothelial cells lining blood vessels ▪ Most frequent tumors of infancy ▪ Develop a few days after parturition ▫ If IH appears to be present at birth → not IH RISK FACTORS ▪ ▪ ▪ ▪ Intrauterine hypoxia Localised hypoxia Biological females more at risk Premature underweight infants COMPLICATIONS Usually none Easily infected, start bleeding Possible ulceration → infection Usually psychosocial: mostly appear on highly visible areas (face, neck, etc.) ▪ Multiple IH in newborns can indicate liver hemangiomas ▪ ▪ ▪ ▪ SIGNS & SYMPTOMS ▪ Appear in first weeks of life ▪ Tumors can grow for ≤ six months after birth ▪ Most regress over time, around five years old ▫ Can leave marks: fibroadipose tissue, changes in pigmentations, scars ▪ Resemble red/white patch, blemish; can be found all over body ▪ Superficial lesions: bright red, flat/raised from the skin → papules AKA “strawberry hemangiomas” ▫ Exposed areas: if grazed, can produce black, crusted, sometimes painful ulceration ▫ > five hemangiomas → ultrasound for hepatic hemangioma ▪ Deeper hemangiomas: bluish lesions, poorly defined ▫ Can proliferate into bigger tumors ▫ Some have superficial capillary counterparts visible over/surrounding affected area ▫ Slower development ▪ Compound hemangiomas: deep IH + superficial IH DIAGNOSIS DIAGNOSTIC IMAGING ▪ Usually no need for imaging Doppler ultrasound ▪ High vessel density and high peak arterial Doppler shift, may show peripheral feeding vessels MRI ▪ Multiple high signal intensity lobules (due to cavernous/cystic spaces containing stagnant blood); often heterogeneous LAB RESULTS ▪ Usually no need for biopsy unless history unclear; used to confirm diagnosis OTHER DIAGNOSTICS History and physical exam ▪ History of onset, age, growth pattern, duration, treatment OSMOSIS.ORG 149
TREATMENT ▪ Most do not require treatment, regress in a few years ▪ Exceptions ▫ Functional issues: feeding (laryngeal hemangiomas), obscuring vision ▫ Bleeding ▫ Hepatic/cardiac complications ▫ Permanent scars causing disfigurement Figure 22.5 A capillary hemangioma on the abdomen of an infant. MEDICATIONS ▪ Beta blockers, oral corticosteroids ▪ Antiangiogenic therapies ▫ Usually intravenous: interferon-alfa 2a, 2b, vincristine SURGERY ▪ Rarely, surgery/laser therapy Figure 22.6 Histological appearance of a capillary hemangioma showing multiple small vascular spaces containing red blood cells. LYMPHANGIOMA PATHOLOGY & CAUSES ▪ Benign lymphatic malformations ▪ Composition: lymphatic channels/cysts ▪ May present at birth/develop during first few years of life TYPES Cystic hygroma (macrocystic) ▪ AKA cavernous lymphangiomas ▪ Composition: cystic masses, dilated lymphatic networks with thin endothelial 150 OSMOSIS.ORG layer; fluid-filled cavities; indistinct margins ▪ One/more cysts ≥ 2cm3/0.8in3 in size ▪ Tends to develop in deep soft tissues; propensity for rapid growth, local invasion of muscle, bone, underlying tissue Lymphangioma circumscriptum (microcystic) ▪ AKA simple/capillary lymphangioma ▪ Composition: capillary-sized endotheliallined lymphatic networks ▪ One/more cysts < 2cm3/0.8in3 in size ▪ Tend to develop in superficial tissues
Chapter 22 Vascular Malformations Mixed ▪ Contains variously-sized cysts CAUSES DIAGNOSIS DIAGNOSTIC IMAGING ▪ Failure to form communication between lymphatic, venous circulation (e.g. jugular lymph sac, internal jugular vein) during fetal development ▪ May be sporadic/associated with genetic mutations (e.g. VEGFR3 germline mutation) MRI ▪ Multiloculated fluid-filled cystic lesions; identifies lesion’s extent RISK FACTORS Histopathology ▪ Cystically dilated channels lined with flat endothelial cells, filled with lymphatic fluid; deeper vessels are large, contain smooth muscle ▪ Chromosomal anomalies ▫ Turner syndrome, Down syndrome, Noonan syndrome (cystic hygroma) Ultrasound ▪ Prenatal cystic mass detection; ↑ nuchal translucency (hypoechoic space) COMPLICATIONS ▪ ▪ ▪ ▪ Lymphedema, recurrent cellulitis Disfigurement Lesion recurrence Fetal hydrops, fetal death, obstructed labor, chylous pleural effusion, chylopericardium, airway compression (cystic hygroma) SIGNS & SYMPTOMS TREATMENT SURGERY ▪ Resection OTHER INTERVENTIONS ▪ Image-guided percutaneous chemoablation ▪ Sclerotherapy Cystic hygroma ▪ Large (up to 15cm/5.9in), poorly-defined soft, fluctuant mass ▫ Commonly located in deeper layers of cervicofacial region, axilla, lateral chest wall ▫ Covered with normal skin Lymphangioma circumscriptum ▪ Slightly elevated lesion ▫ Commonly located in head (oral cavity), trunk, proximal extremities, axillary region ▫ May appear as translucent/hemorrhagic vesicles ▫ Overlying skin may be reddish-purple color secondary to small hemorrhages, thrombus formation/may contain wartlike lesions Figure 22.7 CT scan in the coronal plane demonstrating a large cystic hygroma on the left side of the neck. OSMOSIS.ORG 151
Figure 22.8 Histological appearance of a lymphangioma composed of dilated lymphatic spaces, lined by simple endothelium. 152 OSMOSIS.ORG

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