benign neoplasm of mediastinum (MONDO_0021521, a Monarch Disease Ontology id) is a benign neoplasm that involves the mediastinum. Also known as: benign mediastinal neoplasm, benign mediastinal tumor, benign mediastinal tumour, benign neoplasm of the mediastinum, benign tumor of mediastinum, benign tumor of the mediastinum, benign tumour of mediastinum, benign tumour of the mediastinum.