Alveolar Soft Part Sarcoma Alveolar soft part sarcoma (ASPS) is a very rare type of Soft tissue sarcoma - a slow growing tumor of an unknown origin that arises mainly in children and young adults. ASPS is highly angiogenic: it involves intensive growth of new blood vessels, that connect the tumor to the blood system and enable dissemination of tumor cells into the bloodstream. Tumor cells can then easily migrate into other parts of the body - typically the lungs, and the brain.                  ASPS is a sarcoma, and that indicates that this cancer initially arises in soft tissues that connect, support, or surround other structures and organs of the body, rather than bones. Typically, ASPS arises in muscles and deep soft tissue of the thigh or the leg (lower extremities), but can also appear in the upper extremities: the hands, the neck, and the head. While ASPS is a soft tissue sarcoma, it can spread and grow inside the bones. [ Back ]