Trip Answers

Question answered:22/01/08 Warning! this question is over two years old.

CKS have a guideline on polymyalgia rheumatica and giant cell arteritis [1].  The guideline includes the section ‘How do I know if someone has giant cell arteritis?’ which includes the following passage:

 

“Consider temporal artery biopsy. Although it would be ideal to confirm the diagnosis of GCA in all people by temporal artery biopsy, the precise role of temporal artery biopsy is uncertain. Published opinions of UK experts are that:
 - The temporal artery should be biopsied if the diagnosis is in doubt, because the result would determine the appropriate treatment.
 - Treatment should be started immediately, even if biopsy must be delayed. However, after starting systemic corticosteroids biopsy becomes less useful. Giant cells are less likely to be seen after a couple of weeks, but disruption of the internal elastic lamina is a long-lasting pathological sign.
 - A positive biopsy confirms the diagnosis.
 - A negative biopsy does not rule out GCA, since parts of the artery can be normal with so-called 'skip lesions'. Biopsies of longer arterial section are more sensitive, and thus have better negative predictive values [Younge et al, 2004].”

 

Ganfyd, a medical wiki, reports [2]:

 

“Temporal artery biopsy is a common investigation, and can rule the diagnosis in with high specificity, but is less than perfect at ruling it out.”

 

With regard to the use of steroids prior to a temporal artery biopsy, a 1994 article in Annals of Internal Medicine [3] concluded:

 

“Although these results do not prove that histologic features are unaffected by corticosteroids, they show that, in this large, consecutive sample, the positivity rates of temporal artery biopsy were similar in untreated and corticosteroid-treated patients. Temporal artery biopsy may show arteritis even after more than 14 days of corticosteroid therapy in the presence of clinical indications of active disease.”

 

A more recent (2007) study in the journal Seminars in Arthritis and Rheumatism concluded:

 

“The performance of TAB should not delay the prompt institution of steroid therapy on diagnosis of GCA, since the diagnostic yield of TAB seems valuable within 4 weeks of starting high-dose steroid treatment. In patients that developed GCA on a background of a prior history of PMR, a late TAB is also generally informative despite long-term treatment with low doses of corticosteroids.”

 

References

1) http://www.cks.library.nhs.uk/pmr_and_gca/view_whole_guidance
2) http://www.ganfyd.org/index.php?title=Temporal_arteritis
3) http://www.annals.org/cgi/content/abstract/120/12/987
4) http://bjo.bmj.com/cgi/content/abstract/86/5/530
 

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