3 Surgical pathology of cranial arteritis and polymyalgia rheumatica MARGARET ASHTON-KEY P A T R I C K J. G A L L A G H E R
Although cranial arteritis is one of the most distinctive clinical and pathological disorders that rheumatologists encounter, very little has been learnt over the last century about its underlying cause or pathogenesis. It is only one of a large number of arterial diseases, many of which also require surgical biopsy for diagnosis (Table 1). In the acute phase the histological changes are characteristic, but several arterial diseases with very different clinical symptoms may also have a granulomatous histological appearance (Table 2). LIGHT MICROSCOPIC FINDINGS IN CRANIAL ARTERITIS Horton is credited with the first histological description (Horton et al, 1932) and, in Maladie de Horton, it is he, rather than Hutchinson, who is honoured in the French literature. The early reports correctly emphasized the prominent transmural lymphocytic and macrophage infiltrates which are so characteristic of this disorder (Heptinstall et al, 1954; Kimmelsteil et al, 1954). Histiocytes and giant cells are closely associated with the internal elastic lamella, which is characteristically fragmented. Occasional giant cells appear to contain fragments of phagocytosed elastica (Figures 1 and 2). There is marked intimal thickening, which is the result both of oedema and of intimal fibrosis. This may narrow or completely occlude the vessel, but true luminal thrombosis is uncommon. The histological features of active cranial arteritis must be contrasted with those of normal ageing (arteriosclerosis) or subacute or healed arteritis (Table 3). Arteriosclerosis affects virtually all arteries and arterioles, but the features are often most marked in the kidney, in the splenic and myometrial arteries, and in the vessels surrounding the thyroid. Nevertheless, concentric intimal and medial fibrosis and focal fragmentation and reduplication of the internal elastic lamellae are frequently seen in temporal arteries (Figures 3, 4 and 5) and should not be misinterpreted as evidence of healed arteritis (Ainsworth et al, 1961; Lie et al, 1970). Adventitial aggregates of lymphocytes and macrophages are commonplace in atheromatous vessels Bailli~re's Clinical Rheumatology-Vol. 5, No. 3, December 1991 ISBN 0-7020-1537-7
387 Copyright 9 1991, by Bailli~re Tindall All rights of reproduction in any form reserved
388
M. A S H T O N - K E Y
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Although cranial arteritis is one of the most distinctive clinical and pathological disorders that rheumatologists encounter, very little has been learnt over the last century about its underlying cause or pathogenesis. It is only one of a large number of arterial diseases, many of which also require surgical biopsy for diagnosis (Table 1). In the acute phase the histological changes are characteristic, but several arterial diseases with very different clinical symptoms may also have a granulomatous histological appearance (Table 2). LIGHT MICROSCOPIC FINDINGS IN CRANIAL ARTERITIS Horton is credited with the first histological description (Horton et al, 1932) and, in Maladie de Horton, it is he, rather than Hutchinson, who is honoured in the French literature. The early reports correctly emphasized the prominent transmural lymphocytic and macrophage infiltrates which are so characteristic of this disorder (Heptinstall et al, 1954; Kimmelsteil et al, 1954). Histiocytes and giant cells are closely associated with the internal elastic lamella, which is characteristically fragmented. Occasional giant cells appear to contain fragments of phagocytosed elastica (Figures 1 and 2). There is marked intimal thickening, which is the result both of oedema and of intimal fibrosis. This may narrow or completely occlude the vessel, but true luminal thrombosis is uncommon. The histological features of active cranial arteritis must be contrasted with those of normal ageing (arteriosclerosis) or subacute or healed arteritis (Table 3). Arteriosclerosis affects virtually all arteries and arterioles, but the features are often most marked in the kidney, in the splenic and myometrial arteries, and in the vessels surrounding the thyroid. Nevertheless, concentric intimal and medial fibrosis and focal fragmentation and reduplication of the internal elastic lamellae are frequently seen in temporal arteries (Figures 3, 4 and 5) and should not be misinterpreted as evidence of healed arteritis (Ainsworth et al, 1961; Lie et al, 1970). Adventitial aggregates of lymphocytes and macrophages are commonplace in atheromatous vessels Bailli~re's Clinical Rheumatology-Vol. 5, No. 3, December 1991 ISBN 0-7020-1537-7
387 Copyright 9 1991, by Bailli~re Tindall All rights of reproduction in any form reserved
388
M. A S H T O N - K E Y
~
AND P,J.
GALLAGHER
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