MONDO_0002676 (adult fibrosarcoma) can be described as follows. A malignant mesenchymal neoplasm composed of fibroblasts. It is characterized by collagen production and a herringbone architectural pattern. It is more commonly seen in middle-aged and older adults. It usually affects the deep soft tissues of extremities, trunk, head and neck. Adult fibrosarcomas may recur and metastasize to the lungs and bones. Also known as: adult fibrosarcoma (disease), fibrosarcoma (disease) of adults.