| Despite
the fact that the temporal arteritis was thought
to only affect medium and small arteries of the
head, brain and retina, there have been a lot
of descriptions of generalized involvement which
indicate that it is, indeed, a systemic illness.
This occurs more often in groups of elder people
(below 50years, it's very rare) and is characterized
by pain which follows the temporal artery.
The pathogenesis is unknown, the ethiology is
thought to be autoimmune. Sometimes nodules can
be palpated at the side of the artery because
the arterial wall is enlarged.
Microscopically, there is a partial destruction
of the arterial wall due to an inflammatory infiltrate
which consits of giant cells together with lymphocytes
and histiocytes. The giant cells are of the Langhans
type or foreign body type. A lot of them are found
in relation with the elastic internal lamina and
in some cells, can be found phagocyted fragments
in their cytoplasm. Sometimes, no giant cells
are observed, but instead an inspecific panarteritis
with a monocytal and polynuclear inflammatory
infiltrate. There might be fibrinoid necrosis
and fragmentation, duplication or multilamination
of the elastic internal lamina. The lumen of the
vessel might be reduced and trombosed. In healing
phases, one can find scarred fibrosis which brings
up the differential diagnosis with arterial changes
due to aging.
It's important to emphasizes that the involvement
is segmentarial and that a negative biopsy does
not exclude the diagnosis. In a microscopical
study one always has to make short serials of
the artery. In one clinical study, approx. 60%
of the patients had the specific morphology, but
the other 40% presented unspecific lesions of
arteriosclerosis or ateromatosis and responded
equally to corticoid treatment.
Author: Tomás Castiella Muruzabal
Servicio de Anatomía Patológica
Hospital Clínico Universitario “Lozano Blesa
Zaragoza
English translation by Sandra Dieffenbach |
