INTRODUCTION: We describe an original case of progressive severe dysphagia caused by a posterior mediastinal metastatic melanoma of unknown origin. To the best of our knowledge, such an event has never been described before in the literature. CASE PRESENTATION: A progressive severe dysphagia case is reported induced by a melanoma of unknown origin (metastatic to a posterior mediastinal lymph node). At the time of diagnosis, the lesion appeared as a large posterior mediastinal mass mimicking a neurogenic tumour with oesophageal involvement. After complete resection, pathological assessment of the tumour by immunohistochemistry was consistent with nodal metastatic melanoma. CONCLUSION: This report of a posterior mediastinal lymph node melanoma is unique. The nodal origin is definitely unusual: a primary melanoma should always be carefully ruled out. In fact no other evidence, a part from the absence of the tumour elsewhere, can support the diagnosis of a primary nodal melanoma.