An undifferentiated pleomorphic sarcoma characterized by the presence of osteoclast-like giant cells and cellular pleomorphism. The disease is Monarch Disease Ontology id MONDO_0003561 (malignant giant cell tumor of soft parts). Also known as: giant cell fibrous histiocytoma, giant cell malignant fibrous histiocytoma, malignant Osteoclastoma, malignant giant cell neoplasm of soft parts, malignant giant cell tumor of soft parts (morphologic abnormality), malignant giant cell tumour of soft parts (morphologic abnormality), undifferentiated pleomorphic sarcoma with osteoclast-like giant cells.