spherical dilatations; usually seen at bifurcation of the branches of Circle of Willis

direct (abnormal) communication between venous and arterial vessels that bypass the intervening capillary bed

Segments of the vessel wall are focally thickened by a combination of medial and intimal hyperplasia and fibrosis, resulting in luminal stenosis

Neointimal smooth muscle cell growth stimulated by:

Neointimal growth antagonized by:

Basic lesion: fibro-fatty plaque; primarily involves intimal layer of arteries

Atherosclerosis: preferential locations

made up of fat, cellular elements (leukocytes, monocytes, foam cells or macrophages) and fibrous tissues that encloses the central lipid core

Earliest precursor lesion, no clinical significance, may occur early in newborns and children, usually seen from 0-30 y/o;
Flat, yellow spots or streaks; absence of component of smooth muscle cells

Focal intimal plaque with central core of lipid and covering fibrous cap; affects abdominal aorta, coronary, popliteal, descending thoracic aorta, internal carotid, and circle of Willis

A basic lesion becomes altered through:

Calcium deposits in the media (intima if calcified atherosclerosis) of medium-sized muscular arteries (uterine, testicular arteries); >50y/o

Old age, DM; associated with benign hypertension (systolic hypertension)/benign nephrosclerosis; leakage of plasma components across injured endothelium with hyaline deposition by smooth muscle

Homogenous,pink hyaline deposits in media of arterioles; thickening and hyalinization of the walls

Symptoms: renal insufficiency, uremia, moderate reductions in renal plasma flow with normal or slightly reduced GFR, mild proteinuria

Onion-skin arteriole; concentric proliferation of the intimal and smooth muscle cells of an arteriole; occurs in younger pop.;
associated w/ fibrinoid necrosis = necrotizing arteriolitis

Location of Aneurysm: most likely atherosclerotic in nature unless proven otherwise

Location of Aneurysm: syphilitic in nature unless proven otherwise

Location of Aneurysm: developmental and congenital

Location of Aneurysm: Mycotic

Fusiform dilatation associated with severely atherosclerotic aorta; larger aneurysms, >7-8cm in transverse diameter, associated with mural thrombus; majority caused by atherosclerosis; elderly, usually >50y/p

If symptomatic: pulsatile mass, back pain, severe abdominal pain = a sign of imminent rupture; clinically present with a palpable pulsatile mass with bruits and sounds

Complications of AAA

Typically occur in younger patients who often present with back pain and elevated inflammatory markers;
Cause: presumed localized immune response to the abdominal aortic wall;
May be a vascular manifestation of immunoglobulin G4 (IgG4)-related disease

Type of AAA: Lesions that have become infected by the lodging of circulating microorganisms in the wall

complication of tertiary syphilis with obliterative endarteritis of vasa vasorum → tree barking of aorta (intimal destruction)

Complications of Syphilitic Aneurysm

Tree barking of aorta; superimposed atherosclerosis; 2˚ AV regurgitation and dilatation, LV hypertrophy;
obliterative endarteritis of vasa vasorum (due to surrounding inflammation) → diminished blood supply to the blood vessel → progressive dilatation

Occurs when blood separates the laminar planes of the media to form a blood-filled channel within the aortic wall

Sudden, severe unbearable pain either located in the chest (thoracic aneurysm) or in the abdomen or back (abdominal aneurysm)radiating to the back and downwards

Intimal tear → Medial cleavage by dissecting hematoma → “Double-barreled aorta“ → Cystic medial degeneration or necrosis

General term for inflammation of blood vessel wall

Common pathogenic mechanisms of vasculitis

Large Vessel Vasculitis

Medium Vessel Vasculitis

Small Vessel Vasculitis: ANCA Positive

Small Vessel Vasculitis: ANCA Negative

Formation of Ag-Ab complexes and subsequent deposition in blood vessels

group of autoantibodies directed against azurophil or primary granules of neutrophils, lysosomes of monocytes, and endothelial cells

cytoplasmic location of immunofluorescence stain; also known as Anti-proteinase 3 or PR3-ANCA; associated with Wegener granulomatosis

perinuclear location of immunofluorescence stain; also known as Anti-myeloperoxidase or MPO-ANCA; associated with microscopic polyangiitis, PAN, and Churg-Strauss syndrome

Antibodies to endothelial cells, perhaps induced by defects in immune regulation; associated with Kawasaki disease

Most common vasculitis in elderly females; Chronic, granulomatous inflammation that affects small and medium sized arteries in the head and neck especially temporal arteries

T-cell mediated immunologic reaction against the arterial wall leading to a granulomatous reaction;
S/S: Unilateral throbbing headache (affected temporal artery), facial pain, ocular symptoms

Patients may also have systemic manifestations like muscle pains/aches that appears to be rheumatic in nature called polymyalgia rheumatica

Gross: nodular intimal thickening of the involved artery that reduces the luminal diameter;
Histology: medial granulomatous inflammation w/ multinucleated giant cells that leads to internal elastic lamina fragmentation

Granulomatous vasculitis of medium and large arteries (aorta);
Common in women, < 40 yrs. Old

Ocular disturbance (visual defects, retinal detachment, blindness);
Pulseless disease in the upper extremities (if the brachiocephalic artery is involved)

involves aortic arch plus tributaries and branches; Irregularly thickened intima (hyperplasia), fibrous aortic wall, narrowed lumen due to inflammation = weakened peripheral pulse

granuloma with giant cells, similar to temporal arteritis; patchy necrosis of the media of aorta (medial necrosis); may lead to collagenous scarring; aortic involvement may cause aortic valve insufficiency

Transmural (from adventitia to intima) vasculitis of small or medium muscular arteries (not including arterioles, capillaries, or venules); occurs in young, male adults

Acute Phase: transmural neutrophilic inflammation w/ fibrinoid necrosis & thrombotic occlusion;
Healing Phase: fibrous thickening & mononuclear inflammation;
Healed Phase: marked fibrosis w/ minimal inflammation & nodular consistency

Necrotizing vasculitis; affects arterioles, capillaries and venules; all lesions are of the same histologic age; ANCA positive in majority of cases

Associated with necrotizing glomerulonephritis and pulmonary capilliritis;
Associated with drug hypersensitivity (leukocyte cytoplastic vasculitis)

Hemoptysis; hematuria, and proteinuria; bowel pain or bleeding, muscle pain or weakness; and palpable cutaneous purpura

Segmented fibrinoid necrosis of the media with focal transmural necrotizing lesions; Little or no immunoglobulin can be seen in most lesions = Pauci-immune injury

affects large and medium sized arteries with mucocutaneous syndrome; leading cause of acquired heart disease in children; results from delayed hypersensitivity reaction of T- cells

Young children and infants with coronary artery involvement → aneurysms → rupture of thrombus → Acute MI

T-cell and macrophage activation → cytokine production and macrophage activation; polyclonal B cell activation → formation of autoantibodies to endothelial and smooth muscle cells → Acute vasculitis

S/S: fever; mucocutaneous lymph syndrome (conjunctival and oral erythema and erosion, erythema of the palms and soles, edema of the hands and feet, desquamated rash and cervical lymphadenopathy)

Segmented, necrotizing, fibrinoid (less prominent), panarteritis; inflammation affecting entire thickness of vessel wall; proliferation of autoantibodies

Triad:
Acute necrotizing granulomas of URT/LRT,
Focal necrotizing granulomas and vasculitis of small and medium sized arteries,
Proliferative / crescentric glomerulonephritis

Presence of crescents in the Bowman’s capsule of the glomerulus, related to the proliferation of the epithelial cells of the Bowman capsule → results to obliteration

persistent pneumonitis, cavitation, sinusitis, mucosal erosions of RT, renal disease, fever, muscle pains; necrotizing granulomas of nose, palate, pharynx, lungs

Necrotizing, granulomatous vasculitis of small arteries, veins and capillaries;
Renal lesions: Focal necrotizing GN, Crescentic GN

Destruction of mucous membranes in the nose and lips due to vasculitis, Aphthous stomatitis, Saddle nose deformity, Pulmonary nodules

c-ANCA: speckled pattern in cytoplasm

Segmental, acute and chronic inflammation of medium and small arteries, occasionally veins and nerves; accompanied by luminal thrombosis; associated w/ heavy cigarette smoking, usually seen exclusively in middle-aged (and also young) males

intermittent claudication, pain in the lower extremities, ischemic pain, and then suddenly gangrene sets in, in the lower extremities or in the distal digits, sometimes they may present with autoamputation

Abnormal dilatation and tortuosity of the veins

Caused by the venous dilatation of the anal venous plexus

Affects superficial veins of the upper and lower extremities; caused by a prolonged increase intraluminal pressure and loss of vessel support due to the weakening of vein walls

Renders the venous valves incompetent and leads to lower extremity stasis, congestion, edema, pain, and thrombosis

Complications of Varicose Veins

Acute inflammatory process caused by bacterial seeding of the lymphatic vessels; Affected lymphatics are dilated and filled with an exudate of neutrophils and monocytes

Manifested by red, painful subcutaneous streaks and painful enlargement of the draining lymph nodes

Due to the blockade of lymphatics by filarial worms which mainly affects fatty channels;
Associated with fibrosis of the lymph nodes -> blockade -> lymphedema

most common vascular tumor; tumor of pediatric age group; most regress spontaneously

Most common variant; tends to be superficially located: skin, subcutaneous tissue, mucous membranes of oral cavities and lips; spontaneously regress (75%-90% regression through time); luscious red in appearance

Gross: bright red to blue, flat, elevated or pedunculated lesion;
Histology: lobular proliferation of closely packed, thin-walled blood filled capillaries lined by flattened endothelium.+/- thrombosis

Composed of large, dilated vascular channels; larger, more infiltrative; no regression because they are deeply situated

systemic hemangioma in the cerebellum, brain stem, eye, pancreas, and liver

mass is unencapsulated, has infiltrative borders, and is composed of large, cavernous blood-filled vascular spaces separated by connective tissue stroma

pseudotumor; present as rapidly growing red pedunculated lesions on the skin, gingival, or oral mucosa; bleed easily and often ulcerated; 1/3 develop after trauma; associated with acute and chronic inflammation

benign lymphatic counterpart of hemangiomas; proliferation of blood vessels devoid of blood inside; occurs in the subcutaneous tissue, head, axilla, and neck (can be large in the pediatric age)

notable lateral neck cystic mass; nothing more than a lymphangioma

benign, but extremely painful; arise from glomus bodies; common site: sub-ungal

Characterized by localized dilation of preexisting vessels

most common form of ectasia; usual location : head and neck (superficial);
flat, light pink to purple irregular lesion;
majority ultimately fade and regress spontaneously thru time

only dilation of vessels (with normal volume) in the dermis which are non-neoplastic

May be associated with the Sturge-Weber syndrome aka encephalotrigeminal angiomatosis with distribution along trigeminal nerve

Multiple venous angiomatous masses in the leptomeninges and cortex;
Port wine nevi in ipsilateral face;
Mental retardation, seizures;
Neurologic abnormalities (i.e. hemiplegia, and radiopacities in the skull)

Radial, pulsatile network of dilated subcutaneous arteries which blanches on pressure at the center; usual location: face, neck, or upper chest; associated with pregnancy and cirrhosis

Autosomal dominant; genetic malformations associated with dilated cap & veins; widely distributed: skin, mucous membranes of the oral cavity, lips, and respiratory tract, GIT, and urinary tract

Most common AIDS associated cancer;
Scaly very red, elevated with irregular and varying sizes on the skin

Commonly seen (90%) in older men of Eastern European (esp. Ashke-nazi Jews) or Mediterranean descent;
multiple red to purple skin plaques or nodules in the arms or legs

South Africa , young Bantu children; skin and visceral lesions; local or general lymphadenopathy, skin lesions are sparse; aggressive clinical course

Occurs following organ transplant recipient with high doses of immunosuppressive therapy; skin is involved to a lesser extent; aggressive and involves lymph node, mucosa, and visceral organs (primarily involved)

Skin lesions : 3 stages : multiple red (hemorrhagic), purple patch, plaque, and macules in the extremities

malignant vascular tumor;
common site: skin, soft tissue, breast, liver;
etiogenesis: carcinogenic (arsenic, thorotrast, polyvinyl chloride), chronic lymphedema, radiation, foreign body; clinical behavior: local invasion and high risk for distal metastasis, poor outcome, aggressive

Histology: poorly developed vascular channels with red blood cells in the slits, lined by atypical looking (malignant) hyperchromatic spindle cells

Malignant vascular tumor with characteristic thin-walled branching ("staghorn") vascular pattern microscopically

Histogenesis : pericytes;
Anastomosing vascular channels lined by benign looking endothelial cells;
staghorn pattern