A fibrosarcoma may develop directly in the bone or it may begin in soft tissue and spread to the bone either through the bloodstream or by direct invasion. It is the third most common type of bone tumor. Fibrosarcomas can spread or metastasize to the lungs, heart, kidneys and lymph nodes. This disease is often first noted by the appearance of a mass on the jaw, skull or a leg. Pain may be evident.
Additional signs are dependent on the site of origin and possibly on the site of metastasis.
For instance, limping will be noted if an extremity if involved. Lymph nodes will be enlarged if the fibrosarcoma has metastasized to them and systemic signs may be obvious if other organs are involved. Diagnosis begins with a physical exam including palpation for masses and swollen lymph nodes. Also, the veterinarian will listen to heart and lung sounds as well as evaluate the dog's general condition. As with all cancers, a definitive diagnosis can only be made by biopsy.