Successful treatment of advanced lung adenocarcinoma complicated with Lambert-Eaton myasthenic syndrome: A case report and literature review.

Lambert-Eaton myasthenic syndrome (LEMS) is a rare disease characterized by involvement of the neuromuscular junction. Most cases have an underlying malignancy, especially small-cell lung cancer (SCLC), while adenocarcinoma is less common. Here, we report a rare case of metastatic lung adenocarcinoma complicated with LEMS. In this case, L858R mutation was detected in the 21st exon of the EGFR gene. First-line treatment with gefitinib was given, and the patient has survived for more than six years. Early diagnosis of LEMS and timely and effective treatment can result in a good prognosis. We also searched for "lung cancer", or "carcinoma of lung", or "adenocarcinoma of lung", or "Lambert-Eaton myasthenic syndrome" in PubMed until 1 December 2019. Seven cases of lung adenocarcinoma complicated with LEMS were found, most of which had a poor prognosis. KEY POINTS: This article reports a rare case of metastatic lung adenocarcinoma with EGFR mutation, complicated with LEMS. Gefitinib was given as first-line treatment, and resulted in a good prognosis.