Lambert-Eaton myasthenic syndrome in mixed small cell carcinoma and adenocarcinoma of extrapulmonary origin.

A patient with typical Lambert-Eaton myasthenic syndrome (LEMS) has a clinical manifestation of proximal muscle weaknesses, a larger-than-100% incremental change in repetitive nerve stimulation on high-rate stimulation electrophysiological testing, and a paraneoplastic origin from small cell carcinoma of the lung. Here, we present a patient with an atypical myasthenic syndrome with an oculobulbar-predominant muscle involvement, a borderline incremental change in repetitive nerve stimulation at high frequencies, and a paraneoplastic origin from extrapulmonary mixed small cell carcinoma and adenocarcinoma. The purpose of this report is to emphasize the importance of painstaking scrutiny in the examination of a patient with a less-common presentation of LEMS.