Conservative and surgical approach to intra-articular chondrosarcoma in dogs

Chondrosarcoma (CSA) is a malignant mesenchymal neoplasm. Diagnosis is made through imaging and histological examinations. The prognosis is guarded, and treatment is predominantly surgical in most cases. The objective of this report is to describe an unusual case of intra-articular CSA associated with a cranial cruciate ligament (CrCL) rupture in a dog. A male mixed-breed canine patient, weighing 10.1 kg and nine years old, presented with a history of lameness in the left pelvic limb. After an orthopedic examination, knee radiography and synovial fluid analysis were performed. The results suggested arthritis, joint effusion, and CrCL injury. During surgery, a yellowish mass was identified in the infrapatellar fat pad region, adherent to the cranial portion of the tibial plateau. The mass was excised, and the knee was stabilized using the fabelo-tibial suture technique. Histologically, the tumor exhibited morphological characteristics of well-differentiated chondrosarcoma. The neoplastic cells expressed S100, did not express 1A4, Desmin, AE1AE3, and Osteocalcin, and showed partial expression of Ki67. Adjuvant chemotherapy with doxorubicin and cyclophosphamide was established. The patient had an excellent recovery and was followed up for 455 days postoperatively with no signs of recurrence. In conclusion, a less aggressive surgical approach with limb preservation is an alternative for the treatment of low-grade CSA and should be considered in patients with multiple orthopedic lesions that may compromise ambulation and quality of life.