A benign, intermediate, or malignant neoplasm that arises from the mesenchyma-derived cells of the soft tissue or bone. Representative examples include lipoma, leiomyoma, leiomyosarcoma and osteosarcoma. The disease is Monarch Disease Ontology id MONDO_0002616 (mesenchymal cell neoplasm). Also known as: benign miscellaneous mesenchymal tumor, benign miscellaneous mesenchymal tumour, mesenchymal cell tumor, mesenchymal cell tumour, mesenchymal neoplasm, mesenchymal tumor, mesenchymal tumour.