Clinical and persistent remission in anti-HMGCR immune-mediated necrotizing myopathy to a single cycle of rituximab – a case-based review

case reports and clinical experience are used to guide current management 4 .The European Neuromuscular Centre (ENMC) working group recommends starting treatments with glucocorticoids and an alternative agent such as methotrexate (MTX) 4 .In contrast to other myopathies, IMNM have a worse prognosis, are more likely to relapse and require multiple combination therapies 4 .The use of rituximab (RTX) is limited, and varying responses are described in the literature.We report a case of anti-HMGCR myopathy successfully treated with one cycle of RTX, along with a literature review to further support its use in this disorder. CASE REPORTA 49-year-old Caucasian male patient, autonomous for daily life activities, presented to the emergency department with a 2-week history of myalgia, progressive proximal upper and lower limbs weakness, and a weight loss of 15 kg.He denied the occurrence of fever, anorexia, dyspnea, arthralgia, skin lesions, dysphagia, oral ulcers, photosensitivity, xerostomia, xerophthalmia, Raynaud' s phenomenon, or any other symptoms.He was being treated with 800 mg of metformin and 20 mg of atorvastatin daily for type 2 diabetes mellitus and dyslipidemia, respectively, and had a history of active smoking (34 pack years).Physical examina-ABSTRACT Anti-HMGCR myopathy is an increasingly recognized immune-mediated necrotizing myopathy.However, there are currently no evidence-based treatments available, so case reports and clinical experience are used to guide current management.We report a case of a 49-year-old man, treated with atorvastatin, who presented to the emergency department with progressive proximal muscle weakness.Anti-HMGCR antibodies were detected, and muscle biopsy revealed necrotizing myopathy.Initially, therapy with high-dose glucocorticoids and methotrexate was started, but 12 weeks later, the patient developed clinical deterioration with dysphagia.Then, he was successfully treated with one cycle of rituximab along with physical therapy.The use of rituximab in immune-mediated necrotizing myopathy has been heterogeneously described in the literature but mostly in case reports.The European Neuromuscular Centre working group recommends the use of rituximab in refractory cases.However, some studies highlight the importance of early and aggressive treatment for this disease.Clinical prospective studies are necessary to make proper evidence-based recommendations.