Monarch Disease Ontology term MONDO_0002422 (adamantinoma) is a low grade malignant neoplasm arising from the long bones. The tibia is the most frequently affected bone site. Patients present with swelling which may or may not be associated with pain. Morphologically, it is characterized by a biphasic pattern consisting of an epithelial and an osteofibrous component. The vast majority of cases recur if they are not treated with radical surgery. In a minority of cases the tumor may metastasize to other anatomic sites including lymph nodes, lungs, liver, brain, and skeleton. Also known as: Extragnathic adamantinoma, adamantinoma of long bones, adamantinoma of long bones (morphologic abnormality), adamantinoma, malignant, long bone adamantinoma.