Giant cell arteritis successfully treated with subcutaneous tocilizumab monotherapy

Glucocorticoid remains the mainstay for treatment of large vessel vasculitis (LVV) including giant cell arteritis (GCA); however, the disease affects the elderly for whom the adverse effects of glucocorticoid are problematic. Recently, some reports have suggested that intravenous tocilizumab (TCZ) monotherapy is effective for this disease. To date, it remains unknown whether subcutaneous TCZ monotherapy is also effective. Here, we present a first case of GCA successfully treated with subcutaneous TCZ monotherapy. A 75-year-old woman presented with shoulder and hip pain. She was diagnosed with polymyalgia rheumatica (PMR) and treated with low-dose prednisolone (15 mg daily); however, she discontinued glucocorticoid therapy at her discretion due to the psychiatric adverse effect (cognitive dysfunction). Seven months later, her shoulder and hip pain relapsed. Furthermore, ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) revealed uptake in the descending thoracic aorta, indicating a complication of LVV. She refused to take glucocorticoid for fear of psychiatric adverse effects and chose subcutaneous TCZ monotherapy (162 mg weekly) for treating this life-threatening urgent condition. Nine months later, her shoulder and hip pain resolved and FDG-PET/CT demonstrated no uptake in the descending thoracic aorta, indicating a successful treatment with subcutaneous TCZ monotherapy for the disease. No adverse events and disease relapse were found during observation period. Our case and the literature review suggest that not only intravenous injection but also subcutaneous injection of TCZ monotherapy can serve as an alternative treatment for patients with GCA who have comorbidities or refuse to take glucocorticoid.