A malignant neoplasm arising from muscle tissue, adipose tissue, blood vessels, fibrous tissue, or other supportive tissues excluding the bones. The disease is MONDO_0018078 (soft tissue sarcoma). Also known as: connective tissue sarcoma, malignant mesenchymal tumor, malignant mesenchymal tumour, non-Rhabdo. soft tissue sarcoma, sarcoma of soft tissue, sarcoma of the soft tissue, soft part sarcoma.