Evaluation of deeper levels in initially negative temporal artery biopsies and likelihood of a positive result.

Giant cell arteritis is a vasculitis that affects large- and medium-sized vessels in patients over the age of 50 years. The demonstration of granulomatous arteritis is the criterion standard to establish a definitive diagnosis. However, temporal arteritis is known to discontinuously involve the artery, and there is no standardization of the number of sections which should be examined in a length of sampled artery. The goal of the study is to determine, if by examining additional sections from temporal artery (TA) biopsy cases initially interpreted as negative, do we uncover cases of vasculitis. We conducted a retrospective review of the clinical and histologic features of 75 consecutive temporal artery biopsy cases. Our findings showed that the vast majority (94%) of cases that were biopsy "proven" to be negative for temporal arteritis on initial examination remained negative after examination of all subsequent deeper levels (median of 337 total levels examined). These cases were less likely to show classical GCA signs and symptoms and typically presented at a younger age than the biopsy-positive cases. However, 4 (6%) of the initially "biopsy-negative" cases did turn out to be positive on deeper levels, with 56, 109, 346, and 590 total levels examined, respectively. At least 2 of these 4 patients did not receive prednisone or were weaned off prednisone treatment and experienced persistent/recurrent GCA symptoms. We conclude that routine sampling may miss the diagnosis in a subset of cases and in some cases, sectioning deeper into the paraffin block may be warranted.