Non-small-cell lung cancer associated with non-thymomatous myasthenia gravis

Abstract

A non-small-cell lung cancer without distant metastases was incidentally found in a 77-year-old man who had suffered from myasthenia gravis (MG) without thymoma. The patient's condition was stabilized by oral pyridostigmine bromide which he had taken during the past 6 years. He simultaneously underwent thymectomy and left lower lobectomy with regional lymph node dissection. Although postoperative myasthenic crisis occurred, mechanical ventilation and intravenous steroid pulse relieved the patient and the symptoms improved thereafter. Cases of operable lung cancer with non-thymomatous MG have rarely been reported and the appropriate therapeutic strategy for such cases remains to be debated. Their causal association remains to be identified, whereas some studies have implied that immune disorder due to the abnormal thymus might possibly enhance the oncogenesis of extrathymic malignancies. Myasthenic crisis should also be taken into account in postoperative management of MG patients who simultaneously undergo thymectomy and lobectomy for synchronous lung cancer.

Myasthenia gravis complicated with lung cancer and middle mediastinal thymoma

“…There have been several reports of extrathymic malignancies in MG patients, and a few reports on primary lung cancers complicated by MG. [1][2][3][4][5] Our case had simultaneous occurrence of MG with both thymoma and primary lung cancer, which is considered very rare. To date, a causal association between lung cancer and MG has not been demonstrated.…”

“…4 On the other hand, there are a few reports suggesting that thymoma might increase the prevalence of extra-thymic malignancies. 3,5 Another unique feature in our case was that the thymoma was located in the middle mediastinum, which had differentiated from a metastatic lymph node of the lung carcinoma. Most epithelial cell tumors of the thymus develop in the anterior mediastinum.…”

Distal myasthenia gravis presenting as isolated distal myopathy

“…The severity may be explained by overstimulation of the patient's immune system in response to his chemotherapeutic regimen and his coexisting SCLC. 10,11 The exact mechanism of MG induction is unclear, but it is suspected to be due to cytotoxic T-lymphocyte activation. 12 The possible role of nivolumab in causation is unclear.…”

Lung Cancer Associated with Seronegative Myasthenia Gravis

“…Leukemia, lymphoma, breast cancer, and colon cancer were the most common extrathymic malignant tumors found in these patients with MG (17,18). There are a limited number of lung cancer cases that also present with MG. Table shows the previously-reported cases of MG that were accompanied by lung cancer, of which 7/ 11 cases were also positive for anti-nAChR antibodies (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). In most cases (85%) anti-nAchR antibodypositive MG is accompanied by non-small cell lung cancer.…”

“…However, several cases of lung cancer complicated with myasthenia gravis (MG) have also been reported (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). MG is an autoimmune neuromuscular disease caused by autoantibodies against nicotinic acetylcholine receptors (nAChRs) in neuromuscular junctions.…”