Lung adenocarcinoma with Lambert–Eaton myasthenic syndrome indicated by voltage-gated calcium channel: a case report

Abstract

IntroductionLambert–Eaton myasthenic syndrome is a rare disorder and it is known as a paraneoplastic neurological syndrome. Small cell lung cancer often accompanies this syndrome. Lambert–Eaton myasthenic syndrome associated with lung adenocarcinoma is extremely rare; there are only a few reported cases worldwide.Case presentationA 75-year-old Japanese man with a past history of chronic rheumatoid arthritis and Sjögren syndrome was diagnosed with Lambert–Eaton myasthenic syndrome by electromyography and serum anti-P/Q-type voltage-gated calcium channel antibody level preceding the diagnosis of lung cancer. A chest computed tomography to screen for malignant lesions revealed an abnormal shadow in the lung. Although a histopathological examination by bronchoscopic study could not reveal the malignancy, lung cancer was mostly suspected after the results of a chest computed tomography and [18F]-fluorodeoxyglucose positron emission tomography. An intraoperative diagnosis based on the frozen section obtained by tumor biopsy was adenocarcinoma so the patient underwent a lobectomy of the right lower lobe and lymph node dissection with video-assisted thoracoscopic surgery. The permanent pathological examination was the same as the frozen diagnosis (pT2aN1M0: Stage IIa: TNM staging 7th edition). Immunohistochemistry revealed that most of the cancer cells were positive for P/Q-type voltage-gated calcium channel.ConclusionsOur case is a rare combination of Lambert–Eaton myasthenic syndrome associated with lung adenocarcinoma, rheumatoid arthritis and Sjögren syndrome, and to the best of our knowledge it is the first report that indicates the presence of voltage-gated calcium channel in lung adenocarcinoma by immunostaining.

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

“…We found seven similar cases of lung adenocarcinoma with LEMS (Table ). All cases were diagnosed at an advanced stage, and only two of them were alive at the time of publication of the articles.…”

Lambert–Eaton myasthenic syndrome revealed after surgery of lung adenocarcinoma

“…Clinical symptoms associated typically proximal muscle weakness mostly of the legs, areflexia and autonomic symptoms, [ 1,3 ] others may be present such respiratory, sensory symptoms and autonomic dysfunction like constipation, postural hypotension and dry mouth….. [ 2,3,7,8 ]…”

“…The presumptive of infraclinical diagnosis of LEMS in the pre-operative course that be revealed by the surgical stress can be discussed. LEMS should be distinguished from myasthenia gravis (MG) by the existence of symptoms that affect mainly the lower limbs (weakness) without neither ocular nor bulbar muscles, which are more frequent in MG. [3] Clinical symptoms associated typically proximal muscle weakness mostly of the legs, areflexia and autonomic symptoms, [1,3] others may be present such respiratory, sensory symptoms and autonomic dysfunction like constipation, postural hypotension and dry mouth….. [2,3,7,8] The diagnosis can be established by electrophysiology and specific biologic tests. In electroneuromyography (ENMG), the classic triad first defined by Eaton and Lambert [9] including a low compound muscle action potentials (CMAP), a decremental response at low rate stimulation and an incremental response at high-rate stimulation or after brief exercise (10 s maximal voluntary contraction)…”

“…The presence of high level in serum of the P/G type VGCCs antibodies (voltage-gated calcium channel) is strongly evocating of the LEMS diagnosis, it's reported in 80 −90% of patients with LEMS as well as SOX1 (GANA) was positive in 64% of patients with LEMS/SCLC and considered as an early marker of future predisposition to this association. [1,2,7,8] When a LEMS is associated with cancer, the primary treatment should be cancer resection because LEMS frequently improves with successful cancer therapy.…”

Adenocarcinoma of Lung Presenting as Lambert-Eaton Myasthenic Syndrome

“…A PubMed and Google Scholar literature search discovered only 5 published cases (Table 1) in the literature (English), reporting LEMS associated with pulmonary adenocarcinoma. [1][2][3][4][5] In this article, we report a rare case of LEMS associated with adenocarcinoma of the lung.…”