Temporal artery biopsies
Temporal artery biopsies are submitted when there is a clinical concern about temporal arteritis (also known as giant cell arteritis—GCA—or cranial arteritis). Patients may initially present to the ophthalmologist with sudden and catastrophic visual loss (anterior ischaemic optic neuropathy). They may also have headache or more generalised symptoms such as joint pain associated with polymyalgia rheumatica. Treatment is usually immunosuppression with steroids, which may need to be administered long-term. Because steroids have their own side effects, it is recommended that a confirmatory “tissue diagnosis” of GCA is made early on so that unnecessary treatment is avoided.
Often, it is the ophthalmologist who biopsies the temporal artery, and this is why temporal arteries are frequently submitted to ophthalmic pathology services (as opposed to more general histopathology departments). However, general surgeons, neurosurgeons, vascular and plastic surgeons may also be involved. This means that histopathologists from other specialties may also receive such biopsies. My personal view is that temporal artery biopsies need not be reported by specialist pathologists unlike, say, corneal specimens or eviscerations.
Normal temporal artery
This is an example of a normal temporal artery. The lumen contains fresh blood. The wall is muscular, and there is an elastic lamina. There is no inflammation, and the architecture is regular (no scarring or disorganisation).
The annotated image shows the lumen outlined in yellow. The radial lines marked in green are artefactual (due to the section lying unevenly on the slide).
This higher power view shows the smooth muscle within the wall, as well as the tiny blood vessels (vasa vasorum) supplying the artery itself.
In the annotated image, I’ve outlined the elastic lamina in yellow. In older patients, there may be age-related calcification, which I’ve outlined here in blue.
Abnormal temporal artery
In contrast, this temporal artery shows features of arteritis. On low power, we can see that the wall is irregularly thickened and oedematous (pale area), and that the lumen is thinned. The wall looks “busy” due to an inflammatory infiltrate. There is also inflammation around blood vessels in the adventitia (adjacent soft tissue).
In the annotated image, I’ve outlined (roughly) the oedematous area in yellow. The inflamed adventitial vessels are outlined in green.
On higher power, we can see an infiltrate of lymphocyes and the multinucleate giant cells after which the disease is named.
In the annotated image, I’ve marked the giant cells with asterisks. The lymphocytic infiltrate is diffuse, but they’re more apparent in the area I’ve outlined in yellow.
Watch out: On low power, giant multiple nuclei are sometimes so clumped together that they resemble calcium deposits (ie, both are blue and irregular). Take a few seconds for a closer look.
Here are a few open access articles about giant cell arteritis.
The use of ultrasound to assess giant cell arteritis: review of the current evidence and practical guide for the rheumatologist by Monti et al. This is a fairly recent (2018) review of a new and non-invasive diagnostic tool.
The Diagnosis and Treatment of Giant Cell Arteritis by Ness et al is a general overview of giant cell arteritis.
Polymyalgia Rheumatica and Giant Cell Arteritis by Unwin et al. This is an overview of giant cell arteritis and the closely related polymyalgia rheumatica
In Surgical performance for specialties undertaking temportal artery biopsies: who should perform them?, Galloway etc al propose that a greater proportion of biopsies should be done by ophthalmologists. Their view is rebutted by Fong and Ferguson, who suggest that general and vascular surgeons are also contenders for the role. I’ll let you make up your own minds!
And finally, Chakrabarty and Franks address histopathology issues in Temporal artery biopsy: is there any value in examining biopsies at multiple levels?