Thymoma and Myasthenia Gravis: An Examination of a Paraneoplastic Manifestation

Abstract

Thymoma is a rare type of malignancy but is considered one of the most common neoplasms that occur in the anterior mediastinum. A large proportion of thymomas are associated with paraneoplastic syndromes, such as myasthenia gravis. Whenever feasible, the standard of care for the treatment of thymoma should focus on the control of paraneoplastic syndromes, surgical resection, and adjuvant therapy if appropriate. A 36-year-old female patient with a significant past medical history of obesity and iron deficiency anemia who underwenten bloc resection of thymoma three months prior now presented to the benign hematology clinic to establish care for the management of anemia. Upon review of systems, the patient incidentally reported fatigue, weakness with repetitive motion, occasional blurred vision, headaches, and exertional dyspnea. Physical examination was positive for horizontal nystagmus. Given the patient's history and clinical findings, suspicion of myasthenia gravis was high. Further work-up demonstrated anti-acetylcholine receptor titers of 5.70 nmol/L (normal < 0.21 nmol/L), supporting a diagnosis of myasthenia gravis in this patient. She was subsequently started on pyridostigmine. Often, patients with thymoma experience paraneoplastic syndrome-related symptoms prior to thymectomy, and in many cases thymectomy is curative. However, in the case presented, we examine a patient that was asymptomatic prior to surgery and subsequently reported the onset of symptoms following what we suspect was an exacerbation due to general anesthesia and pain control medications. We argue that all patients with thymoma should undergo systematic evaluation and treatment of paraneoplastic syndromes, regardless of clinical symptoms and prior to surgery, in order to improve patient quality of life and hospital outcomes.