Sarcomas are tumors that arise in the soft, connective tissues that support and surround the organs and other structures of the body. A spindle cell sarcoma is a soft tissue sarcoma whose cells exhibit a spindle shape, with an elongated body that is wider in the middle and tapers to a point at each end. The spindle cells arise among actively dividing cells engaged in abnormal patterns of cell division, and they exhibit strands of collagen and stretched out nuclei. Spindle cell sarcomas occur rarely due to the typically slow rate of replication of connective tissues under normal circumstances. Researchers believe there are several possible causes for a spindle cell sarcoma, including genetic predisposition, exposure to radiation or certain chemicals, trauma, and inflammation, all of which may stimulate the tissues to divide more rapidly than normal.

Research has shown that some chromosomal mutations and other genetic conditions may predispose an individual to the development of a spindle cell sarcoma. Oncogene, tumor suppressor genes, and other cellular genetic defects have been isolated that exhibit an association with connective tissue sarcomas. For example, a Neurofibromatosis-1 gene (NF1) codes for the development of diffuse fibrous tumors throughout the body in patients with neurofibromatosis, and these lesions can undergo malignant change. Genetic testing plays a key role in diagnosis, and genetic engineering may one day provide effective therapies for the prevention of spindle cell sarcomas.

Much like other tumors that arise after irradiation, a spindle cell sarcoma can occur in tissues that have been irradiated for other cancers. The radiation may induce genetic mutations that lead to uncontrolled cell division. Additionally, various environmental or industrial chemicals have been linked to the development of spindle cell sarcomas, including vinyl chloride and arsenic. The relationship between a spindle cell sarcoma and trauma is unclear, but the involved mechanism may be related to inflammation in the injured tissues. Alternatively, diagnosis of a tumor in an area is more likely when the tissue is examined after an injury.

Infection also may lead to the formation of a spindle cell sarcoma. The most common example of an infection-related sarcoma is Kaposi’s sarcoma. Kaposi’s sarcoma is characterized by multiple purple, red, or blue elevated patches in the skin, respiratory tract, gastrointestinal tract, and mouth. These tumors occur in patients with acquired immunodeficiency syndrome (AIDS) and Herpesvirus Type 8 infections. Herpsevirus Type 8 is a distinctive human tumor virus that has integrated into its genetic material genes that cause tumors, which also allow the virus to evade detection by the immune system.