Page 247 - Concise Pathology for Exam Preparation ( PDFDrive )

232 SECTION II Diseases of Organ Systems

Pathogenesis

Attributed to T-cell-mediated immunologic reaction against arterial wall components.
Clinical Features

Symptoms vary from being nonspecific (fever, fatigue and weight loss) to severe headache
and blindness (caused due to ophthalmic artery involvement).
Gross Pathology

The affected arteries are thickened and cord like, with narrowing of the lumina.
Microscopy

• Sections show chronic granulomatous reaction with giant cells, usually around the
internal elastic lamina, typically involving the entire circumference of the vessel wall.
• Internal elastic lamina is fragmented with presence of giant cells of foreign body or
Langhans type.
• Eccentric or concentric intimal cellular proliferation may cause luminal narrowing.

Q. Write briefly about polyarteritis nodosa (PAN).
Ans. Polyarteritis nodosa is a systemic necrotizing vasculitis involving small- and medium-
sized muscular arteries.
Salient Features of Polyarteritis Nodosa
• Affects adults (males more commonly affected than females).
• Kidneys, heart, liver, GIT, muscle, pancreas, testes, nervous system and skin are usually
involved with sparing involvement of pulmonary or glomerular vessels.
• Hypertension
Pathogenesis
Deposition of immune complexes and hepatitis B antigenaemia is implicated.

Clinical Features
(due to ischaemia and infarction of the affected tissues and organs)
• Fever, malaise, weakness and weight loss
• Renal manifestations (albuminuria and haematuria)
• Abdominal pain and melena
• Peripheral neuritis

Gross Pathology
• Transmural (involvement of whole thickness of the vessel wall) and segmental (involvement
of only a portion of the vessel circumference) vasculitis of small- and medium-sized
muscular arteries.
• Predilection for bifurcations and branching points.
• Segmental erosion with weakening of arterial wall may cause aneurysmal dilation or
localized rupture.
Microscopy
• Acute stage: Transmural inflammation (chiefly neutrophils and eosinophils) with
fibrinoid necrosis
• Healing stage: Fibroblastic proliferation with chronic inflammation (lymphocytes,
plasma cells and macrophages)
• Healed stage: Thickened arterial wall due to dense fibrosis. Haemosiderin-laden
macrophages and organized thrombi may be seen
All stages of inflammation can be present at the same time.

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