Purpose:
To study relationship between temporal artery biopsy (TAB) length and the diagnostic sensitivity for giant cell arteritis (GCA), and to investigate the diagnostic yield of bilateral TAB compared to unilateral TAB.
Methods:
TAB pathology reports were reviewed for histological findings and formalin-fixed TAB lengths. Patients’ charts were reviewed for clinical data. TAB was considered positive if there was a mononuclear cell infiltrate in the vessel wall. Biopsy-negative GCA was diagnosed when patients fulfilled the American College of Rheumatology classification criteria, in addition to rapid response to steroid therapy. Patients were divided into 3 groups according to the clinical and histological features: Biopsy-positive GCA, biopsy-negative GCA, and no GCA.
Results:
305 TAB reports of 173 individuals were reviewed (TAB was performed bilaterally in 132 cases). The table shows the number (%) of positive TAB in relation to the TAB length, and the mean TAB length of each group. * P<0.001 compared to the other groupsTAB length affects the rate of positive histological findings, with length >10 mm yielding 50% diagnostic sensitivity, compared to 31% when length was 6-10 mm (p=0.003). 51 of the 70 biopsy-positive GCA patients had bilateral TAB. In 13 of the 51 cases (25%) TAB was positive on one side only. In 8 of the 13 cases the length of TAB on the positive side was longer than the negative side, in 3 cases lengths were equal. The mean length of TAB on the positive side was 15.5+8.9 mm, compared to 10.0+5.4 mm on the negative side (p=0.07).
Conclusions:
The histological diagnosis may be missed in 12.5% of GCA cases with unilateral biopsies. It is suggested that TAB needs to be performed bilaterally, and final TAB length should be more than 10 mm. Considering the possible shrinkage of a specimen in formalin fixation, the original length should be at least 15 mm.
Keywords: vascular occlusion/vascular occlusive disease • inflammation • pathology: human