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Título

Refractory Re-thymectomy and Immunotherapy in Myasthenia gravis: Case Report

RESUMO

Case presentation: A 41-year-old patient, female, previously healthy, presented to this service in 2017 with a myasthenic syndrome, referring progressive bulbar musculature weakness associated with bilateral ptosis without fatigability maneuver, being later diagnosed with myasthenia gravis (Osserman Classification IIIa). In clinical-radiological evaluation (CT), a mass with 60 cm³ of volume was identified in the anterior mediastinum, and subsequent histopathological analysis of Thymoma (Masaoka I) was associated with the positivity of Anti-AChR (1,28). She has been refractory to traditional therapy methods, like using glucocorticoids, Intravenous Immunoglobulin (IVIG), and acetylcholinesterase inhibitors in optimized dosage, keeping the progression of symptoms and being at risk of hypercapnic respiratory failure. As a result of recent scientific evidence regarding the surgical benefit of thymectomy in these select patients, she underwent a Video-assisted Thoracoscopic Surgery (VATS) to remove the mass. However, despite IV pulse therapy and the measures previously adopted, the patient continued to experience progressive clinical worsening, requiring a definitive airway proper to hypoxemia and carbon dioxide narcosis. Due to the recurrence of the disease, it required immunotherapy with Rituximab, Cyclophosphamide, and a second surgical re-approach for a new removal of the recurrent mass. Since then, there has been partial improvement in fatigability control through this second investigation of ectopic secretion of anti-AchR.

Discussion: Myasthenia gravis is a neuromuscular transmission disorder resulting from the binding of autoantibodies to components of the neuromuscular junction (NMJ), most commonly the acetylcholine receptor (AChR). These autoantibodies are directly responsible for the pathological change in the endplate - being dependent on CD4+ T and B cells. It is characterized by fatigable muscle weakness, with a variable course with a tendency to progress to distal muscles. A particular subpopulation is restricted to ocular and facial manifestations. Other autoantibodies involved are anti-MuSK and anti-LRP4, acting on proteins responsible for maintaining the NMJ and on the ability to emit action potentials at the endplate, respectively.

Conclusion: In this presentation, we describe a patient with refractory Myasthenia gravis, leaving the usual pattern of clinical control and suggesting the importance of the thymus in the pathophysiology.

Palavras Chave

Myasthenia gravis; Thymectomy; Refractory