Ophthalmoplegia associated with lung adenocarcinoma in a patient with the Lambert–Eaton myasthenic syndrome

RATIONALE The Lambert-Eaton myasthenic syndrome (LEMS) is a neuromuscular disease; its unique symptoms of LEMS include dry mouth with a metallic taste, constipation, and erectile dysfunction. As it is quite rare, isolated ocular muscle impairment associated with LEMS east to ignore. PATIENT CONCERNS A 65-year-old man presented with alternating ptosis and diplopia. Isolated ocular muscle impairment had lasted for 6 years, and the patient was initially diagnosed with ocular myasthenia gravis (MG). Treatment with azathioprine only slightly improved symptoms over the first 2 months; long-term treatment was not effective. DIAGNOSES Dynamic observation of chest computed tomography images revealed a slowly progressing nodule in the lower lobe of the left lung. The subsequent pathologic examination following mass resection confirmed a diagnosis of lung adenocarcinoma. INTERVENTIONS The patient was ultimately diagnosed with the Lambert-Eaton myasthenic syndrome associated with pulmonary adenocarcinoma. OUTCOMES Resection of the lung tumor relieved all symptoms. LESSONS Other causes of ocular MG symptoms should be considered when standard MG therapy is ineffective, especially the Lambert-Eaton myasthenic syndrome.