An aggressive malignant smooth muscle neoplasm, arising from the esophagus. It is characterized by a proliferation of neoplastic spindle cells. The disease is Monarch Disease Ontology identifier MONDO_0003365 (esophagus leiomyosarcoma). Also known as: esophageal leiomyosarcoma, leiomyosarcoma of esophagus, leiomyosarcoma of oesophagus, leiomyosarcoma of the esophagus, leiomyosarcoma of the oesophagus.