Page 249 - Concise Pathology for Exam Preparation ( PDFDrive )

234 SECTION II Diseases of Organ Systems

Microscopy

Shows segmental and focally transmural lesions which involve smallest vessels, sparing
medium-sized and large arteries. Two histological forms are seen:
• Leukocytoclastic vasculitis: Vasculitis is due to immune complex deposition. There is fibrinoid
necrosis with neutrophilic infiltrate in the vessel wall. Many neutrophils appear fragmented.
• Lymphocytic vasculitis: Vascular injury occurs due to lymphocyte-macrophage-mediated
delayed hypersensitivity.

Q. Write briefly about Churg–Strauss syndrome (also called ‘allergic
granulomatosis and angiitis’).
Ans. Churg–Strauss syndrome is a rare small vessel vasculitis.

Salient Features

• It is a multisystem disease characterized by necrotizing vasculitis with granulomas and
eosinophilic necrosis.
• Has a strong association with allergic rhinitis, bronchial asthma, lung infiltrates and
eosinophilia.
• Commonly affects vessels in the lungs, heart, spleen, peripheral nerves and skin. Renal
disease is less frequent.
• Coronary arteritis and myocarditis are the main causes of death.
Pathogenesis

Thought to result from hyperresponsiveness to an allergic stimulus. ANCAs are positive in
50% cases.

Clinical Features

• Palpable purpura (due to involvement of skin)
• Gastrointestinal bleeding
• Focal and segmental glomerulosclerosis
• Cardiomyopathy (in .50% patients)

Microscopy
• Infiltration of vessels and perivascular tissue by eosinophils without overt vasculitis in
the early phase.
• Intravascular and extravascular granulomas with vasculitis in later stage.

Q. Write briefly about Wegener granulomatosis (granulomatosis
with polyangiitis).

Ans. Wegener granulomatosis is a necrotizing vasculitis characterized by a clinicopatho-
logical triad of:
1. Necrotizing granulomas of the upper respiratory tract (ear, nose, sinuses and throat)
and/or lower respiratory tracts (lungs).
2. Focal necrotizing granulomatous vasculitis of the small- to medium-sized vessels.
3. Focal necrotizing crescentic glomerulonephritis.

Pathogenesis

• May represent a T-cell-mediated hypersensitive response to some inhaled infectious
or environmental agent.
• Characterized by presence of immune complexes (in vessel wall and glomeruli) and
PR3–ANCA, which is a good marker of the disease.

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