Florid Arteritis Confined to a Single Branch of the Superficial Temporal Artery

Biopsy of the superficial temporal artery provides vital confirmation of the diagnosis of giant cell arteritis. The vessel splits into 2 main branches: frontal and parietal. It is unknown which branch is most likely to yield a positive biopsy finding or, indeed, whether arteritis is ever confined to a single branch.

A 69-year-old woman had a 5-week history of neck stiffness and malaise. The erythrocyte sedimentation rate was 55 mm/h. A 30-mm segment of the parietal branch of the left superficial temporal artery was harvested. It was processed with hematoxylin-eosin stain and an elastic Van Gieson stain. A total of 108 sections were examined at 36 different levels. None showed evidence of arteritis (Figure 1). Two days later, a 30-mm section of the frontal branch of the left superficial temporal artery was biopsied. Every section showed extensive granulomatous inflammation (Figure 2). The patient was treated with prednisone and her symptoms resolved.

It is crucial to obtain a biopsy specimen of adequate length to avoid the problem of “skip areas” in the superficial temporal artery. It is also important to examine the specimen thoroughly by reviewing sections cut at many levels because inflammation can be confined to just a few portions of the artery. Otherwise, there is risk of a false-negative biopsy result.^1,2 We describe an extreme example of a skip area: a parietal branch completely free of inflammation in a patient with extensive arteritis of the frontal branch. To our knowledge, no prior report has compared pathological findings in the 2 branches of the superficial temporal artery. In fact, surgeons usually fail to specify which branch was biopsied when they submit specimens, and no histological data exist regarding which branch is more likely to demonstrate arteritis.

Recently, it was suggested that the parietal branch, rather than the frontal branch, should be biopsied in patients with suspected temporal arteritis.³ This approach eliminates the remote risk of facial nerve injury and usually hides the scar behind the hairline. However, this recommendation was predicated on the assumption that the prevalence of arteritis is equal in the parietal and frontal branches. We now show that selective involvement of a single vessel branch can occur in temporal arteritis.

Magnetic resonance imaging has been used to compare the involvement of the parietal vs frontal branch in temporal arteritis. In 21 patients with suspected giant cell arteritis, involvement was rated by noting the amount of mural thickening and gadolinium enhancement of the vessel and perivascular tissue.⁴ On the left side, abnormalities were present in 14 patients in the frontal branch and in 6 patients in the parietal branch. On the right side, involvement was noted in 11 patients in each branch. These data hint that arteritis may be more prevalent in the frontal branch than the parietal branch. Notably, in the majority of patients who had imaging signs of temporal arteritis, abnormalities were present in one branch but not the other, at least on one side. Although neuroimaging is not equivalent to the gold standard of histopathological analysis, this result suggests that selective involvement of a single branch of the superficial temporal artery is not rare.

Bilateral temporal artery biopsy is sometimes performed to improve the chance of obtaining a positive result, especially if systemic symptoms are present. However, only a handful of patients will have a negative biopsy finding on one side and a positive biopsy finding on the other side.^5,6 If a second biopsy is contemplated, it may be more fruitful to sample the other branch of the artery on the same side rather than the same branch on the other side. In the future, surgeons should record whether they have biopsied the frontal or parietal branch so that data can be gathered to determine which branch is inflamed most frequently. This information may increase the diagnostic yield of temporal artery biopsy.

Correspondence: Dr Horton, Beckman Vision Center, University of California, San Francisco, 10 Koret Way, San Francisco, CA 94143 (hortonj@vision.ucsf.edu).

Funding/Support: This work was supported by grants EY10217 (Dr Horton) and EY02162 (Beckman Vision Center) from the National Eye Institute and by Research to Prevent Blindness.