A Case of Lambert-Eaton Myasthenic Syndrome Improved after Surgical Resection for Diagnosis of Small Cell carcinoma of the Lung

소세포 폐암의 확진을 위한 수술후 호전된 소세포 폐암에 의한 Lambert-Eaton 근무력 증후군 1예

Lambert Eaton myasthenic syndrome(LEMS) is a paraneoplastic syndrome caused by defects in the secretion of acetylcholine from the presynaptic membrane of nerve terminals and is strongly associated with small cell lung carcinoma. The pathogenesis of LEMS is the destruction of voltage gated calcium channels by an autoimmune process resulting in clinical manifestations consisting of lower extremity weakness. decreased deep tendon reflexes and autonomic dysfunctions. The diagnosis can be confirmed by the characteristic clinical features and repetitive nerve stimulation. The neurological symptoms and signs of LEMS may manifest themselves months before the clinical manifestation of the underlying malignancy. Therefore early diagnosis and treatment of the primary malignancy may become possible through the diagnosis of this rare paraneoplastic syndrome. We report a case of a patient diagnosed with LEMS who upon further evaluation for an underlying malignancy was found to have a 0.2 cm sized nodular and infiltrative mass lesion at the bifurcation of the left apicoposterior segmental and anterior segmental bronchi by bronchoscopy. Although repeated bronchoscopic biopsies of the lesion was not able to disclose malignancy, under strong clinical suspicion left upper lobectomy was performed and subsequently the diagnosis of small cell carcinoma of the lung was confirmed. Muscle weakness began to improve starting from a week after the surgery, then reached a plateau 2 weeks later. Muscle weakness improved further after the trial of anticancer chemotherapy.

소세포 폐암에 동반된 LEMS는 부종양성 증후군의 일종으로 LEMS가 진단된 환자의 50% 이상에서 소세포 폐암이 동반되는데 특히 흡연력이 있는 고령에서 잠재성암을 진단하기 위한 적극적인 노력이 필요하다. 저자 등은 기괸지경 검사상 조직학적으로 진단되지 않았으나 폐암이 강력히 의심되어 적극적으로 수술적 치료를 시행하여 소세포 폐암을 진단하였고, 수술 후 LEMS의 임상양상이 호전되었으며 항암 화학요법후 추가로 호전된 증례를 경험하였기에 문헌 고찰과 함께 보고하는 바이다.