Summary

The authors describe a case of 60-year-old male patient presented with a 6 month history of progressive weakness of all the four limbs, ataxia, droopy eyelids and bulbar features. Further laboratory and electrodiagnostic studies confirmed the diagnosis of Lambert–Eaton myasthenic syndrome (LEMS). MRI of the brain showed a cerebellar tumour which, following surgery was revealed to be a metastatic small-cell lung carcinoma. Paraneoplastic LEMS together with solitary cerebellar metastasis was diagnosed but no evidence of primary malignancy was detected. An extensive search for related malignancies failed to get any clue. The patient underwent a total surgical excision of tumour and the histopathology revealed a metastatic small cell carcinoma. This case highlights that rarely both paraneoplastic LEMS and cerebellar mass can precede the primary malignancy causing them.