Comparison of pre-formalin fixation and postfixation temporal artery biopsy lengths

Abstract

Objective: To evaluate the difference in temporal artery biopsy length before and after formalin fixation and identify any correlations with pathologic diagnosis.

Design: Prospective case series.

Participants: Patients undergoing temporal artery biopsy between June 2020 and October 2021.

Methods: The pre- and postfixation biopsy lengths were compared. The primary outcome was the difference in temporal artery length as measured before fixation by the surgeon versus the postfixation measurement by the pathologist.

Results: Forty-seven consecutive biopsies in 46 patients were included. One patient had a repeat biopsy. Mean age was 75.3 ± 8.4 years (range, 49-94 years); 74% of patients (34 of 46 patients) were female. Mean prefixation biopsy length was 2.36 ± 0.58 cm (range, 1.1-4.5 cm). Mean postfixation biopsy length was 2.09 ± 0.59 cm (range, 0.6-3.8 cm). Mean difference (postfixation shrinkage) was 0.27 ± 0.24 cm (p = 0.0298), and 36% of biopsies (17 of 47 biopsies) were positive. There was no significant difference in prefixation temporal artery biopsy length (p = 0.38) or postfixation shrinkage (p = 0.24) between positive and negative biopsies. In a univariate analysis, elevated erythrocyte sedimentation rate was 31.3 mm/h (range, 4-88 mm/h) in negative biopsies versus 54.5 mm/h (range, 29-98 mm/h) in positive biopsies (p = 0.01), C-reactive protein was 17.4 mg/L (range, 0.2-145 mg/L) in negative biopsies versus 78.56 mg/L (range, 5-244.4 mg/L) in positive biopsies (p = 0.003), and platelets were 254.9 × 10⁹/L (range, 134-570 × 10⁹/L) in negative biopsies versus 393.8 × 10⁹/L (range, 210-593 × 10⁹/L) in positive biopsies (p < 0.001), all associated with a positive pathologic diagnosis.

Conclusions: The average temporal artery biopsy was approximately 0.27 cm shorter on pathologic reports compared with before fixation measurements. Surgeons should account for this shrinkage with a buffer of at least 0.3 cm, aiming for excision of at least 2.3 cm, if they desire a postfixation size of 2 cm.