Page 418 - Textbook of Pathology, 6th Edition

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  TABLE 15.4: Contrasting Features of Syphilitic Aortitis and Aortic Atheroma.
Feature Syphilitic Aortitis Aortic Atheroma
1. Sites Ascending aorta, aortic arch; Progressive increase from the arch to abdominal
absent below diaphragm aorta, more often at the bifurcation
2. Macroscopy Pearly-white intimal lesions resembling Yellowish-white intimal plaques with fat in the core;
tree-bark without fat in the core; ulceration ulceration and calcification in plaques common
and calcification often not found
3. Microscopy Endarteritis and periarteritis of vasa Fibrous cap with deeper core containing foam
vasorum, perivascular infiltrate of plasma cells, cholesterol clefts and soft lipid
cells and lymphocytes
4. Effects Thoracic aortic aneurysm, incompetence Abdominal aortic aneurysm, aortic valve stenosis,
of the aortic valve, stenosis of coronary ostia stenosis of abdominal branches

II. NON-INFECTIOUS ARTERITIS liver, gastrointestinal tract, muscle, pancreas, testes, nervous
system and skin. The syndrome of PAN presents with varied
This group consists of most of the important forms of symptoms pertaining to different organs. However, some
vasculitis, more often affecting arterioles, venules and usual clinical features are fever, malaise, weakness, weight
capillaries, and hence also termed as small vessel vasculitis. loss, renal manifestations (albuminuria, haematuria and renal
Their exact etiology is not known but available evidence failure), vascular lesions in the alimentary tract (abdominal
suggests that many of them have immunologic origin. Serum pain and melaena), peripheral neuritis and hypertension. The
from many of patients with vasculitis of immunologic origin condition is believed to result from deposition of immune
show the presence of following immunologic features:
complexes and tumour-related antigens.
1. Anti-neutrophil cytoplasmic antibodies (ANCAs).
Patients with immunologic vasculitis have autoantibodies Grossly, the lesions of PAN involve segments of vessels,
in their serum against the cytoplasmic antigens of the especially at the bifurcations and branchings, as tiny
neutrophils, macrophages and endothelial cells; these are beaded nodules.
called ANCAs. Neutrophil immunofluorescence is used to Microscopically, there are 3 sequential stages in the
SECTION III
demonstrate their presence, of which two distinct patterns evolution of lesions in PAN:
of ANCAs are seen: i) Acute stage—There is fibrinoid necrosis in the centre
Cytoplasmic ANCA (c-ANCA) pattern is specific for of the nodule located in the media. An acute inflammatory
proteinase-3 (PR-3), a constituent of neutrophilic granules; response develops around the focus of fibrinoid necrosis.
this is seen in cases with active Wegener’s granulomatosis. The inflammatory infiltrate is present in the entire
Perinuclear ANCA (p-ANCA) pattern is specific for circumference of the affected vessel (periarteritis) and
myeloperoxidase enzyme; this is noted in patients with consists chiefly of neutrophils and eosinophils, and some
microscopic polyarteritis nodosa and primary glomerular mononuclear cells. The lumen may show thrombi and the
disease. weakened wall may be the site of aneurysm formation.
ii) Healing stage—This is characterised by marked
2. Anti-endothelial cell antibodies (AECAs). These
antibodies are demonstable in cases of SLE, Kawasaki disease fibroblastic proliferation producing firm nodularity. The
Systemic Pathology
and Buerger’s disease. inflammatory infiltrate now consists mainly of
lymphocytes, plasma cells and macrophages.
3. Pauci-immune vasculitis. While most cases of iii) Healed stage—In this stage, the affected arterial wall is
immunologic vasculitis have immune complex deposits in markedly thickened due to dense fibrosis. The internal
the vessel wall, there are some cases which do not have such elastic lamina is fragmented or lost. Healed stage may
immune deposits and are termed as cases of pauci-immune contain haemosiderin-laden macrophages and organised
vasculitis (similar to pauci-immune glomerulonephritis, thrombus.
Chapter 22). Pathogenesis of lesions in these cases is
explained by other mechanisms. However, it may be mentioned here that various stages
of the disease may be seen in different vessels and even
Polyarteritis Nodosa within the same vessel.
Polyarteritis nodosa (PAN) is a necrotising vasculitis invol- Hypersensitivity Vasculitis
ving small and medium-sized muscular arteries of multiple
organs and tissues. ‘Polyarteritis’ is the preferred Hypersensitivity vasculitis, also called as allergic or leuco-
nomenclature over ‘periarteritis’ because inflammatory cytoclastic vasculitis or microscopic polyarteritis, is a group
involvement occurs in all the layers of the vessel wall. of clinical syndromes differing from PAN in having
The disease occurs more commonly in adult males than inflammatory involvement of venules, capillaries and
females. Most commonly affected organs, in descending arterioles. The tissues and organs most commonly involved
order of frequency of involvement, are the kidneys, heart, are the skin, mucous membranes, lungs, brain, heart,