T.N.A. Garcez1; F.S. Teixeira1; W.K. Beheregaray1; R.T. Oliveira1; C.S. Cardoso1; A.O. Fernandes1; G.C. Gianotti1; C. Gomes1; E.A. Contesini2
Chondrosarcomas are malignant cartilaginous tissue tumors, very likely to relapse but with low metastasis incidence, slow-growing and locally invasive. It is possible to classify them into myxoid and mesenchymal subtypes. The primary treatment to both histological variants is surgery and there is no consensus in the literature about radiotherapy or chemotherapy as complementary therapies. This work reports a case of myxoid chondrosarcoma in a rabbit, its clinical signs, treatment and results. A mixed breed three year-old male rabbit, 4.3 kg, was assisted at the Veterinary Medical Teaching Hospital of the Federal University of Rio Grande do Sul. The patient was limping and showed increased volume in the distal portion of the right pelvic limb. The nodule was firm and joined to palpation and it had grown progressively for about one year. Radiographic examination and fine-needle aspiration biopsy were taken and the X-ray showed an image compatible with severe joint destruction. Cytology was inconclusive. Based on physical and radiological examination, amputation of the limb at the proximal femur was recommended. Histopathological analysis of the material diagnosed grade II myxoid chondrosarcoma. Unlike the expectation, since this type of tumor in dogs and cats is more commonly found in the axial skeleton, the tumor was located in the appendicular skeleton, similar location to the expected in humans. For both types of myxoid chondrosarcoma, hematogenous spread occurs late and metastatic commitment is mainly in the lung. Though being a chondrosarcoma grade II, chest X-ray for metastasis detection was not taken as the patient did not return for review in which the results of histopathological examination were available. Prognosis is related to location, resection possibility and grade. The prognosis was considered favorable since it was an intermediate grade tumor and surgical excision had been performed with wide safety margin. As for the surgical procedure, the injured area determines which technique is the most indicated. In male dogs, amputation at the proximal femur is used because it allows protection of external genitals. Besides, this technique was chosen in this case because it is faster and more practical. The patient recovered movement well, returning to previously performed functions such as walking, running and jumping. Thus, amputation controls the primary tumor and provides relief of pain with little or no reduction in mobility and quality of life, besides its good aesthetic and functional results, being therefore a procedure generally well accepted by owners.