Seropositive Myasthenia Gravis Associated with Small-Cell Lung Carcinoma

Abstract

BackgroundLambert-Eaton myasthenic syndrome is well known to be a classical paraneoplastic syndrome of small cell lung carcinoma (SCLC). Three cases of seronegative myasthenia gravis (MG) and SCLC were previously reported.Case ReportA 65-year-old man developed a severe progressive respiratory failure with clinical features of MG. Tests showed a decremental response in the repetitive nerve stimulation test, abnormal single-fiber electromyography, and positive acetylcholine receptor antibody. SCLC was confirmed by the lung biopsy.ConclusionsThis case represents the first case of seropositive MG and SCLC.

Acetylcholine receptor antibody-positive myasthenia gravis associated with small-cell lung cancer

“…To the best of our knowledge, only four cases of MG associated with SCLC have been reported. [ 6 – 9 ] Moreover, of these, only one case was AChR-ab positive, [ 6 ] making our patient the second case of AChR-ab-positive MG associated with SCLC to be reported. While the present case initially presented with bilateral eyelid ptosis and edrophonium test positivity, the most typical initial symptom of MG is ocular weakness with asymmetric ptosis and binocular diplopia.…”

“…[ 11 ] In the present case, the standard MG treatment failed to stabilize the MG symptoms; thus, anticancer therapy was administered, which controlled the MG symptoms. Among three previous case reports of synchronous SCLC and MG, [ 6 – 8 ] the efficacy of SCLC treatment for controlling MG was described in only one report. [ 7 ] This report also described that combination therapy of standard MG treatment and anticancer treatment stabilized the MG symptoms.…”

“…[ 3 ] In addition, in a prospective study, LEMS occurred in 3% of SCLC patients. [ 5 ] On the other hand, case reports of MG associated with SCLC are limited, [ 6 – 9 ] and cases positive for AChR-ab are even rarer. [ 6 ] Moreover, the efficacy of standard MG treatment, such as cholinesterase inhibitor therapy, immunosuppressive therapy using steroids and immunosuppressive drugs, plasma exchange, and intravenous immune globulin (IVIg), [ 4 ] for these cases 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.…”