Monarch Disease Ontology entry MONDO_0021515 (benign neoplasm of ethmoidal sinus) is a benign neoplasm that involves the ethmoid sinus. Also known as: benign ethmoid sinus neoplasm, benign ethmoid sinus tumor, benign ethmoid sinus tumour, benign ethmoidal sinus neoplasm, benign ethmoidal sinus tumor, benign ethmoidal sinus tumour, benign neoplasm of ethmoid sinus, benign neoplasm of the ethmoid sinus.