An odd case of immune-mediated necrotizing myopathy, complicated with sagittal, transverse and sigmoid sinus thrombosis

Abstract

INTRODUCTION: Immune-mediated necrotizing myopathy (IMNM) is a rare variant of immune-mediated inflammatory myopathy (IMIM) that exhibits a severe prognosis and is unresponsive to conventional treatment. (1,2)Notably, the incidence of immune-mediated inflammatory myopathies (IMIMs) is low, estimated at 1.16 to 19/million/year and only 3-6% of IMIMs are diagnosed as IMNM. (1,3–5). Systemic inflammation has been found to play a crucial role in promoting the onset of cerebral venous thrombosis. (6,7) MATERIAL AND METHODS: We present the case of a 46-years-old Chinese woman, without any known prior pathology, who was referred to the Rheumatology Department for symmetrical, proximal muscle weakness of the limbs, dysphagia for solid food, and weight loss (5 kg within 2 months). The pathologic clinical examination revealed itchy erythematous plaques on the posterior thoracolumbar region and signs of muscle weakness. Laboratory workup showed significant inflammatory syndrome, severe muscle and hepatic cytolysis syndrome, and positivity for thyroid-specific autoantibodies but with normal thyroid function, positivity for antinuclear antibodies (more precisely: SS-A, Ro-52, SS-B), and myositis antibodies (SRP, Ro-52, SAE1, PM-Scl, MDA5). The CT scan of the thoracic, abdominal, and pelvis showed fibrosis of the lungs, hepatic hypertrophy, and an enlarged uterus, further diagnosed by transvaginal ultrasound as adenomyosis. The positive diagnosis is immune-mediated necrotizing myopathy. Differential diagnoses included dermatomyositis, toxic/infectious myositis, hypothyroidism, and neuro-muscular diseases (5,8). The initial treatment was made with glucocorticoids (pulse therapy followed by oral therapy) and immunosuppressants (Mycophenolate Mofetil – stopped because of severe dyspepsia and myelosuppression). After five days of pulse therapy, the patient developed muscle weakness and paresthesia on the left side of the body, and the cerebral CT scan revealed sagittal, transverse, and sigmoid sinus thrombosis. Thrombophilia screening uncovered the positivity of the lupus anticoagulant. (9) RESULTS: The patient was treated with anticoagulants (low molecular weight heparin, and afterward Vitamin K antagonist), low doses of oral glucocorticoids, and immunosuppressant (Methotrexate), without any other adverse event. CONCLUSION: In the presence of the lupus anticoagulant, even though the antiphospholipid syndrome is not confirmed, the only anticoagulant therapy that has proven its efficacy is the Vitamin K antagonist. Immune inflammatory myopathies, like IMNMs, create a significant inflammatory status that leads to hypercoagulability and endothelial injury, which exposes collagen and tissue factors, promoting further platelet aggregation, and can even lead to cerebral thrombosis. (2,6)