Page 419 - Textbook of Pathology, 6th Edition

gastrointestinal tract, kidneys and muscle. The condition multiple organs and tissues. Most commonly involved 403
results from immunologic response to an identifiable antigen organs are the lungs, paranasal sinuses, nasopharynx and
that may be bacteria (e.g. streptococci, staphylococci, kidneys. Other involved organs are joints, skin, eyes, ears,
mycobacteria), viruses (e.g. hepatitis B virus, influenza virus, heart and nervous system. Accordingly, clinical features are
CMV), malarial parasite, certain drugs and chemicals. variable. Typical features include pneumonitis with bilateral
Hypersensitivity vasculitis includes clinicopathologic entities infiltrates in the lungs (Chapter 17), chronic sinusitis, naso-
such as serum sickness, Henoch-Schönlein purpura, mixed pharyngeal ulcerations (Chapter 18) and renal disease
cryoglobulinaemia, vasculitis associated with malignancy, (Chapter 22). The etiology is not known but possibly the
and vasculitis associated with connective tissue diseases like lesions occur due to the presence of circulating immune
rheumatoid arthritis and SLE. complexes. This is supported by the observation of
subepithelial immunoglobulin deposits on the glomerular
Microscopically, the lesions characteristically involve basement membrane and induction of remission by immuno-
smallest vessels, sparing medium-sized and larger suppressive therapy. The serum of these patients shows
arteries. Two histologic forms are described: c-ANCA positivity. Disseminated form of Wegener’s
i) Leucocytoclastic vasculitis, characterised by fibrinoid granulomatosis differs from a related entity, idiopathic lethal
necrosis with neutrophilic infiltrate in the vessel wall. midline granuloma, in the sense that the latter condition is
Many of the neutrophils are fragmented (Fig. 15.13). This highly destructive and progressively necrotic disease of the
form is found in vasculitis caused by deposits of immune upper airways.
complexes.
ii) Lymphocytic vasculitis, in which the involved vessel Histologically, the characteristic feature of Wegener’s
shows predominant infiltration by lymphocytes. This type granulomatosis is the presence of necrotising granulo-
is seen in vascular injury due to delayed hypersensitivity matous inflammation of the tissues and necrotising
or cellular immune reactions. vasculitis with or without granulomas:
The granulomas consist of fibrinoid necrosis with
extensive infiltration by neutrophils, mononuclear cells,
Wegener’s Granulomatosis
epithelioid cells, multinucleate giant cells and fibroblastic CHAPTER 15
Wegener’s granulomatosis is another form of necrotising proliferation.
vasculitis characterised by a clinicopathologic triad consisting The necrotising vasculitis may be segmental or circum-
of the following: ferential.
i) Acute necrotising granulomas of the upper and lower The renal lesions are those of focal or diffuse necro-
respiratory tracts involving nose, sinuses and lungs; tising glomerulonephritis.
ii) focal necrotising vasculitis, particularly of the lungs and
upper airways; and Temporal (Giant Cell) Arteritis
iii) focal or diffuse necrotising glomerulonephritis. This is a form of granulomatous inflammation of medium-
A limited form of Wegener’s granulomatosis is the same sized and large arteries. Preferential sites of involvement are
condition without renal involvement. As with PAN, the the cranial arteries, especially the temporal, and hence the
condition is more common in adult males and involves name. However, the aorta and other major arteries like
common carotid, axillary, brachial, femoral and mesenteric
arteries are also involved, and therefore, it is preferable to The Blood Vessels and Lymphatics
call the entity as ‘giant cell arteritis’. The patients are generally
over the age of 70 years with slight female preponderance.
The usual clinical manifestations are headache and blindness
if ophthalmic artery is involved. An association with
polymyalgia rheumatica has been observed. The cause of the
condition remains unknown though there is suggestion of T
cell mediated immunologic reaction to some component of
the arterial wall, especially against the damaged internal
elastic lamina. Biopsy of the affected artery is not only of
diagnostic value but also relieves the patient of painful
symptoms.
Grossly, the affected artery is thickened, cord-like and the
lumen is usually reduced to a narrow slit.
Histologically, the features include the following:
i) There is chronic granulomatous reaction, usually
around the internal elastic lamina and typically involves
the entire circumference of the vessel.
ii) Giant cells of foreign body or Langhans’ type are found
Figure 15.13 Leucocytoclastic vasculitis. The vessel wall shows in two-third of cases.
fibrinoid necrosis surrounded by viable as well as fragmented neutrophils.