SEVERE HYPOFIBRINOGENEMIA IN A PATIENT WITH GIANT CELL ARTERITIS TREATED WITH TOCILIZUMAB: CASE-BASED REVIEW

The Giant cell arteritis (GCA) is the most common form of systemic vasculitis in elderly patients. The treatment includes high doses of steroids and interleukin (IL)-6 inhibitor tocilizumab, especially in refractory or relapsing disease or in cases where there is an increased risk of steroid-related adverse events. This report discusses the case of a patient with giant cell arteritis who underwent treatment with tocilizumab for four years. The treatment was successful and resulted in clinical remission. However, four years after starting the therapy, the patient developed spontaneous hematomas on their extremities. After further investigation, it was discovered that the patient had developed thrombocytopenia and hypofibrinogenemia, which required substitution therapy. Malignancy and immune-mediated causes of hypofibrinogenemia and thrombocytopenia were ruled out. The patient experienced an extended period of hypofibrinogenemia that lasted for two months after the last dose of tocilizumab. During this time, the levels of CRP remained very low. This could be because the continued inhibition of IL-6 caused impaired hepatic synthesis of acute phase response proteins, which led to low fibrinogen and CRP levels in serum. The purpose of this case-based review is to emphasize the necessity of regular fibrinogen check-ups in GCA patients treated with tocilizumab.