| How is the general structure of vascular wall? | . |
| What are types of vessels? | Arteries (elastic, muscular and arteriole <0.3 mm)
Capillaries
Veins
Lymphatic vessels |
| What is vasculitis? | • Heterogeneous group of disorders characterized
by inflammation and damage of the blood vessel.
• The lumen of the involved vessel is usually
narrowed → may lead to ischemia of the tissues
supplied.
• Classification: May be classified
– According to size of the vessel involved
– Role of immune complexes, and presence of specific
autoantibodies
– Granuloma formation
– Organ specificity |
| What are types of vasculitis? | . |
| Figure of types of vasculitis? | . |
| What is giant cell arteritis? | • Chronic, typically granulomatous inflammation of
medium- and large-sized arteries.
• Vessels involved: One or more branches of the carotid
artery (e.g. temporal artery). Can involve multiple
arteries, aorta (giant-cell aortitis) and its branches.
• Pathogenesis: T cell–mediated immune response
against an unknown antigen. Proinflammatory
cytokines (TNF) and antiendothelial antibodies may also
be involved.
• Diagnosis: confirmed by biopsy of the temporal artery |
| How is morphology of giant cell arteritis? | Gross:
Involved segment of the artery show nodular thickening of
the intima → reduces the size of lumen → ischemia.
Microscopy
• Granulomatous inflammation (within the inner tunica
media centered on the internal elastic lamina. It shows
multinucleated giant cells)
• Fragmentation of elastic lamina.
• Chronic inflammation (consisting of T cells and
macrophages.)
• Segmental distribution of inflammation with segments of
relatively normal artery between the lesions.
• Intimal fibrosis in healed stage. |
| What is polyarteritis nodosa? | • Systemic, necrotizing vasculitis of small and medium-sizedmuscular arteries characteristically involving the renal and visceral arteries.
• It spares the smallest blood vessels (arterioles, venules, and capillaries). PAN does not involve pulmonary arteries.
• Etiology: Cause not known in the majority of cases. About 30% of patients with PAN have chronic hepatitis B with HBsAg-HbsAb complexes in affected vessels. This indicates an immune complex–mediated etiology in this subset.
• Vessels involved: Vessels of the skin, kidneys, heart, liver,
peripheral nerves, and gastrointestinal tract. |
| How is microscopy of PAN? | • Lesions are segmental.
• Characteristically, the lesions at different stages
of development coexist in different vessels or
even within the same vessel.
• Transmural necrotizing inflammation of small to
medium-sized arteries → weakens the wall of
artery → can lead to aneurysms or rupture.
• Gross: Nodular lesions mainly at the points of
arterial branchings. Aneurysms may also be seen. |
| How are acute phase and late phase PAN? | Acute phase:
• Transmural inflammation of the arterial wall and perivascular infiltration by neutrophils and eosinophils.
• Fibrinoid necrosis
• Thrombosis → infarction of the tissues supplied by the involved vessel.
• Aneurysm (up to 1 cm in size) → may rupture → produce hemorrhage.
Late phase:
• Subacute and chronic stages: Acute inflammatory infiltrate replaced by mononuclear cells.
• Fibrous thickening of the vessel wall → further occlusion of the vessel lumen. |
| What is microscopic angiitis? | • It is a necrotizing vasculitis that generally affects
capillaries, as well as small arterioles and venules.
• It is also called hypersensitivity vasculitis or
leukocytoclastic vasculitis.
• Unlike polyarteritis nodosa, all lesions of microscopic
polyangiitis tend to be of the same age in any given
patient and are distributed more widely.
• The skin, mucous membranes, lungs, brain, heart,
gastrointestinal tract, kidneys, and muscle can all be
involved; necrotizing glomerulonephritis (90% of
patients) and pulmonary capillaritis are particularly
common. |
| How is microscopy of microscopic angiitis? | • Segmental fibrinoid necrosis of the media and focal transmural necrotizing lesions; granulomatous inflammation is absent.
• These lesions morphologically resemble PAN but typically spare medium-sized and larger arteries; consequently, infarcts are uncommon.
• In some areas (typically postcapillary venules), only infiltrating neutrophils, many undergoing apoptosis, are seen, giving rise to the term leukocytoclastic vasculitis |
| What is Wegner's granulomatosis? | • Classic Wegener's granulomatosis is a necrotizing vasculitis, which involves the upper respiratory tract, the lungs, and the kidneys.
Pathological Hallmarks
1. Acute necrotizing granulomatous inflammation in the upper respiratory tract or the lower respiratory tract (lung). It may present as chronic sinusitis and mucosal ulcerations of the nasopharynx.
2. Necrotizing or granulomatous vasculitis affects small to medium-sized vessels (e.g. capillaries, venules, arterioles, and arteries). It may present with persistent pneumonitis and bilateral nodular and cavitary infiltrates.
3. Renal lesion in the form of focal and segmental necrotizing, often crescentic, glomerulonephritis. |
| What are lesions of Wegner's? | 1. Upper respiratory tract lesions: They range from inflammatory sinusitis to ulcerative lesions in the nose, palate, or pharynx.
2. Lower respiratory tract: Lung shows multiple, bilateral, nodular cavitary infiltrates. Microscopically, it is characterized by:
a. Necrotizing granulomas: It consists of geographic patterns of central necrosis surrounded by a zone of fibroblastic proliferation with giant cells, reminiscent of mycobacterial or fungal infections. The granulomas may be either intravascular or extravascular.
b. Necrotizing vasculitis of small arteries and veins.
3. Renal lesions:
a. Early lesions: Glomeruli show focal and segmental necrotizing glomerulonephritis.
b. Advanced lesions: They are characterized by rapidly progressive crescentic glomerulonephritis (RPGN). |
| What are hemangiomas? | • Very common benign tumor of blood vessels
• Capillary hemangioma
( Skin, oral mucosa, sometimes organs, "Strawberry” type present at birth, regresses)
• Cavernous hemangioma (Organs, sometimes skin, Cosmetic problem (unless in brain))
• Pyogenic granuloma (Rapidly growing red nodule on skin, in mouth, Microscopically resembles granulation tissue) |
| What is kaposi sarcoma? | • Vascular neoplasm caused by human herpes virus 8 (HHV8)
• Four forms: Chronic (older Ashkenazi Jewish males), African, transplant-associated, AIDS-associated
• Tends to be indolent but may be locally aggressive
• Skin is predominant site
• May also affect lymph nodes, visceral organs or mucosa
• Excision can be curative
• Infiltrative proliferation of spindled endothelial cells
• Slit-like vascular spaces formed by spindled endothelial cells with minimal to moderate atypia.
• Extravasated erythrocytes and hemosiderin are key histologic clues |
| What is angiosarcoma? | • Malignant neoplasm showing morphological or
immunophenotypic evidence of endothelial differentiation
• Skin (H&N), soft tissues, breast (Primary/2nd), liver
• Wide morphologic appearance: Well-differentiated to
anaplastic
• Metastasize rapidly. 5ys 30%.
• Irregularly shaped anastomosing vascular channels or sheet-like growth
• Highly infiltrative architecture and poor demarcation
• Multilayering of endothelial cells, nuclear atypia, increased mitoses, necrosis
Positive for vascular markers, such as CD31, CD34, ERG, VEGF and factor VIII, by IHC |
| What are cardiac tumors? | • cardiac fibroma
• cardiac myxoma
• cystic tumor of the atrioventricular node
• papillary fibroelastoma
• rhabdomyoma
• angiosarcoma
• rhabdomyosarcoma |
| How is epidemio of cardiac tumors? | •Most common: metastatic
heart is a rare site of metastasis
lung cancer, lymphoma most common
•Primary tumors uncommon, most are benign
•Atrial myxoma is the most frequent primary cardiac
tumor in adults
•Papillary fibroelastoma is the most common tumor of
the cardiac valves, accounting for 75% of valvular
tumors
•Rhabdomyosarcoma predominates in children |
| What is cardiac myxoma? | • Most often occurring as a solitary, sporadic,
pedunculated mass in the left atrium;
• ~10% occur in the context of Carney syndrome
• May mimic malignant neoplasia because of frequent
embolism, systemic or obstructive symptoms
• May cause sudden death, usually due to mitral valve
obstruction
• Excellent prognosis but treatment requires complete
surgical resection to avoid / prevent relapse and
embolic or systemic symptoms
The tumor is lobulated and polypoid with soft gelatinous
appearance. |
| How are histological features of cardiac myxoma? | • Complex structures (cords, nests, rings or poorly
formed glands).
• Stellate or globular myxoma cells (lepidic cells)
with abundant eosinophilic cytoplasm.
• Abundant mucopolysaccharide (myxoid) ground
substance
• Absence of necrosis, mitotic activity and
significant cell atypia |
| What is papillary fibroelastoma? | • Benign papillary growth of endocardium and avascular
fibroelastic tissue
• Typical patient: 60 - 70 years but can be seen in all ages
• Considerable variation to clinical presentation
– Most commonly asymptomatic , diagnosed incidentally
(routine imaging or at the time of cardiac surgery for an
alternate indication)
– May present with syncope, myocardial infarction or
sudden death
• Imaging is the most classic means of diagnosis
• Benign behavior but may result in morbidity / mortality from downstream (thrombo) embolization
• Excellent prognosis with surgical removal |
| What is rhabdomyosarcoma? | • Sarcoma with striated muscle differentiation
• Rare, 4 - 7% of cardiac sarcomas but most
common cardiac malignancy in infants and
children
• Occurs throughout heart, not just in left
atrium as with other sarcomas
• Usually children / young adults
• Metastases to lung, regional nodes, CNS, GI
tract, kidney, other |
| How is presentation of rhabdomyosarcoma? | • Bulky, invasive, central necrosis
• Almost always myocardial involvement
• May involve mitral valve or atrial wall
• Malignant soft tissue tumors, exhibiting skeletal muscle
differentiation.
• Tumor cells range from small primitive hyperchromatic
round/spindle cells to large differentiated ribbon/
tadpole shaped cells with abundant eosinophilic
cytoplasm and cross-striations (rhabdomyoblasts)
• IHC: positive for MyoD1, Myogenin A, Muscle Specific
Actin or Desmin |
