Primary fibrosarcoma are a rare malignant neoplasia of fibrous connective tissue in dogs.
These tumors are associated with defects or rearrangements in chromosomes 11 and 30.
Primary fibrosarcomas are found mainly in older large-breed dogs (e.g. Rottweiler, Labrador retriever), these tumors arises from both bone and soft tissue and although are mainly located in the metaphyseal area of long bones and pelvis, but have been reported in the oral cavity, maxillary bone, pericardium, trachea, urinary bladder and skin (keloid fibrosarcoma).
Affected dogs usually present with lameness or peripheral weakness, often involving one or both hind-limbs. A swelling may be obvious on clinical examination. Facial swellings are obvious with maxillary or oral tumors. Unfortunately, these ORAL tumors are difficult to detect until they become large because they frequently occur at the back of the mouth.
Radiographic evidence may suggest a bony mass but a definitive diagnosis requires biopsy material examined by histopathology. Immunohistochemically, these tumours often labelled positively for vimentin, calponin and alpha-smooth muscle actin. grading of malignancy can now be determined using minichromosome maintenance proteins, which are produced in 70% of canine fibrosarcomas.
Care should be taken to differentiate primary fibrosarcomas of bone from fibrosarcomas of soft tissue origin, which may invade adjacent bony structures. Differentiation may be especially difficult when the tumors arise in the oral cavity, where soft tissue fibrosarcomas of gingival and palatine origin are locally invasive of adjacent bony structures.
Periosteal fibrosarcomas may also arise mainly from the mandible and maxilla. They are slowly growing tumor masses, intimately attached to the bone surface, that with time will erode and destroy the adjacent bony tissue.
Oral fibrosarcomas usually require rostral mandibulectomy or total hemimandibulectomy.
Survival rates following aggressive therapy range from 1 - 2 years.
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