Eosinophilic giant cell arteritis: A different subset of disease?

•Approximately 1 in 10 patients with transmural GCA has an eosinophilic infiltration at TAB.•Eosinophilic GCA is characterized by a more severe inflammation and cranial signs/symptoms without allergic manifestations.•Acute thrombosis and laminar necrosis, expression of eosinophilic damage, are more frequently observed at TAB. To describe the clinical findings, response to therapy and course of patients with transmural eosinophilic infiltration at temporal artery biopsy (TAB). The study consisted of a retrospective cohort of 254 consecutive GCA patients with evidence of transmural inflammation at TAB seen at the Santa Maria Nuova Hospital over a 28-year period. The findings of the 22 patients with eosinophilic infiltration (≥ 20 eosinophils/hpf) at TAB were compared with those of 232 patients without. Among these 232 patients, we sampled 42 GCA patients matched for age, sex and follow-up duration to the 22 with eosinophilic infiltration, to compare allergic manifestations. GCA patients with eosinophilic infiltration compared to those without presented more frequently cranial symptoms (p = 0.052), headaches (p = 0.005), abnormalities of TAs at physical examination (p = 0.045), jaw claudication (p = 0.024), and systemic manifestations (p = 0.016) and had higher CRP levels at diagnosis (p = 0.001). Regarding histological lesions, a severe transmural inflammation, laminar necrosis and intraluminal acute thrombosis were more frequently observed in patients with eosinophilic infiltration (p = 0.066, p < 0.001, and p = 0.010, respectively). Long-term remission and flares were similar in the two groups. When 21 GCA patients with eosinophilic infiltration were compared to 42 without, blood eosinophilic counts at diagnosis were normal and no patients had evidence or developed allergic manifestations and/or clinical findings of systemic necrotizing vasculitis. Patients with transmural eosinophilic infiltration represent a subset of GCA with cranial disease and more severe inflammation.