What is the most common malignant tumor found in adults?

Angiosarcoma is the correct answer because it is recognized as the most common type of malignant tumor found in adults, particularly in the soft tissue. This tumor typically arises in blood vessels and can occur in various locations throughout the body. Angiosarcomas have an aggressive nature and often arise in areas that have been exposed to radiation or in sites of lymphedema.

Rhabdomyosarcoma is more commonly encountered in children and is a malignant tumor of mesenchymal origin characterized by skeletal muscle differentiation. Fibrosarcoma is also a malignant tumor of connective tissue, but it is less prevalent in adults compared to angiosarcoma. Myxosarcoma, while a malignant tumor, is not as frequently diagnosed, making it comparatively rare in adults. This underscores why angiosarcoma stands out as the most common malignant tumor in the adult population.