Copyright 2001 American Medical Association. All Rights Reserved.
Applicable FARS/DFARS Restrictions Apply to Government Use.2001
The diagnosis of giant cell arteritis (GCA) is confirmed by finding
characteristic histological changes in the disease in an arterial segment,
such as the superficial temporal artery. The length of the arterial specimen
is crucial because of the presence of "skip lesions"1
(areas of no inflammation) in GCA. Recently, there has been discussion concerning
the required length of an arterial specimen to securely confirm or exclude
the diagnosis of GCA.2,3
It is generally accepted that 20 mm is an adequate specimen length for a unilateral
biopsy. In a "Letter to the Editor" in the Journal of the
American Medical Association, the issue has been raised as to whether
this is a prefixation or postfixation measurement guideline and whether formalin
fixation reduces the effective length of a temporal artery biopsy specimen.4 This is a potentially important question since
the accuracy of the histological diagnosis of GCA is believed to be strongly
correlated to the length of the fixed artery specimen that is available for
pathological assessment. We report the first available data that directly
address this question.
All patients undergoing temporal artery biopsy at Wills Eye Hospital
(Philadelphia, Pa) between January 15 and July 1, 1999, were prospectively
enrolled. Immediately upon excision of the temporal artery segment and prior
to the placement of the specimen in 10% neutral buffered formalin fixative,
the length of the specimen was measured in the operating room by the surgeon.
It was later remeasured after fixation before sectioning by the pathologist,
who was masked as to the initial measurement. Both sets of measurements were
done using the same standardized millimeter rulers with measurements being
made to the nearest tenth of a millimeter.
Twenty-eight temporal artery biopsies were performed. Fifteen were positive
and 13 were negative for shrinkage. The average prefixation length was 28.4
mm (SD, 6.0 mm), whereas the average postfixation length was 26.0 mm (SD,
5.5 mm), representing a mean shrinkage of 2.4 mm (95% confidence interval,
1.6-3.1 mm; P<.001, 2-tailed test) or a mean
reduction of about 8% (6%-13%). Twenty-two biopsy specimens were measured
between 3 and 6 hours of being placed in fixation, and 6 were measured within
12 hours of fixation. No statistical difference was detected between these
Our study shows that shrinkage of temporal artery biopsy specimens does
occur following formalin fixation. This observation suggests that clinicians
may need to take slightly longer temporal artery biopsy specimens than previously
recommended to insure that shrinkage due to chemical fixatives does not reduce
diagnostic accuracy in the investigation of this treatable but potentially
sight-threatening condition. While a 20-mm sample of temporal artery is generally
considered to be an adequate biopsy specimen, because of the presence of skip
lesions, the shorter the biopsy specimen, the more important the shrinkage
factor is to diagnosis.
Corresponding author: Helen V. Danesh-Meyer, MD, Discipline of Ophthalmology,
University of Auckland, Private Bag 92019, Auckland, New Zealand (e-mail: email@example.com).
Danesh-Meyer HV, Savino PJ, Bilyk JR, Eagle RC, Sergott RC. Shrinkage: Fact or Fiction?. Arch Ophthalmol. 2001;119(8):1217. doi: