Abstract
INTRODUCTION: Focal myositis is a rare inflammatory disease characterised by localised involvement of a single muscle or muscle group. Involvement of the sternocleidomastoid muscle represents an extremely rare localisation. MATERIALS AND METHODS: We report the case of a 78-year-old woman who developed progressive left laterocervical swelling and pain following a respiratory infection. Extensive clinical and radiological investigations were performed; however, a definitive diagnosis was achieved only after muscle biopsy. RESULTS: The patient initially responded to corticosteroid therapy but subsequently developed steroid dependence. For long-term disease control, methotrexate was introduced as a steroid-sparing agent. The clinical course was notable for recurrent disease exacerbations associated with fever. DISCUSSION: This case presents several distinctive features, including occurrence in an elderly patient, the presence of fever during disease flares, and a steroid-dependent course requiring second-line immunosuppressive therapy. These aspects contribute to the diagnostic and therapeutic complexity of focal myositis, particularly in atypical localisations. CONCLUSION: Our experience highlights the diagnostic challenges associated with this rare entity and suggests that prolonged immunosuppressive treatment may be necessary in selected patients with focal myositis.