"Chondrosarcoma" TUMOR TIDBITS, A BIWEEKLY VETERINARY ONCOLOGY E-LETTER Volume 3; Number 4; February 1, 2002. Editor: Kevin A. Hahn, DVM, PhD, Dipl - ACVIM (Oncology) & Overall Nice Guy! ANNOUNCEMENTS 1 - Come Celebrate! We're having a Celebration of Life reception Saturday March 23rd at Gulf Coast Veterinary Oncology. Bring a picture of your pet to place in our new display case. Sorry, no pets allowed since we will be celebrating in our Deli. 2 - Free chemotherapy for lymphoma! Beginning April 15th, we will be offering a free chemotherapy trial for dogs diagnosed but previously untreated lymphoma at our Houston Office. Check our web site regulary for details!!!! www.gcvs.com THIS WEEK'S TUMOR TIDBIT: CHONDROSARCOMA OVERVIEW OF WHAT'S IN THE TEXTBOOKS: ·Malignant neoplasm arising from cartilage characterized histologically by malignant cartilage ·Second most common primary bone tumor in dogs, but represents less than 10% of all primary bone tumors ·More common in the axial skeleton ·Most common primary rib tumor ·Must differentiate from chondroblastic osteosarcoma ·Histologic grade helpful in predicting survival in patients with long-bone chondrosarcoma ·High-grade tumors behave similarly to osteosarcoma in respect to metastatic potential ·Metastasizes to any tissue, but lung is the most common site ·Most common in large (not giant) breeds of dog ·Uncommon in cats SIGNS ·Lameness ·Pain in affected limb ·Visible swelling at tumor site PHYSICAL FINDINGS Long-bone tumors ·Monostotic swelling, typically in metaphyseal site. ·Pain on palpation of tumor site. ·Pathologic fracture in some patients. Rib tumors ·Asymptomatic palpable mass in thoracic wall. ·Pleural effusion secondary to intrathoracic extension of tumor in some patients. DIFFERENTIAL DIAGNOSES ·Other primary bone neoplasm, including osteosarcoma, fibrosarcoma, and hemangiosarcoma, can be clinically indistinguishable from chondosarcoma. ·Metastatic bone lesion from another primary site. ·Osteomyelitis (i.e., fungal or bacterial). DIAGNOSTIC RESULTS ·Laboratory results usually normal. ·Biopsy and histopathologic examination of suspected tumor as described for osteosarcoma. ·Small specimens of osteosarcoma may be misdiagnosed as chondrosarcoma. IMAGING ·Findings on radiographs of primary lesion may be impossible to differentiate from those of other primary bone tumors--lytic or productive lesions, or both. Lesions in long bones usually located in metaphyseal sites. ·Thoracic radiography to detect metastasis. ·CT may be helpful to determine local extent of disease, especially in patient with rib tumor. ·Nuclear bone scan or radiographic scan of entire skeleton useful for staging. TREATMENT ·Surgical resection (amputation or limb salvage) to remove primary tumor. ·Chest wall resection (and reconstruction if necessary) in patient with rib tumor. ·Hemipelvectomy in patient with tumor involving bones of the pelvis. ·Consider radiotherapy for palliation in patient with inoperable tumor. FOLLOW-UP ·Thoracic radiography monthly for 3 months followed by every third month thereafter. ·Prognosis in patients with low-grade tumor of long bones, excellent; cure possible . ·Prognosis for patients with high-grade tumors of long bones, guarded to poor; survival statistics similar to those for patients with osteosarcoma. WHAT DO WE DO AT GULF COAST? ·After complete clinical staging (exam, xrays), we consider full-thickness bone biopsies in at least 3-4 sites to rule out an underlying osteosarcoma. ·If truly a chondrosarcoma, the very best option is complete surgical removal (amputation) for a good chance for cure. ·If amputation is not a consideration, considerable pain relief can be obtained using radiation (either full-course with intent for cure of the local tumor, or short-course for palliative pain control), with good expectations of most dogs enjoying use of the leg for 1 year. ·Options for chemotherapy are few due to the chronic nature of most tumors, but considerations for palliative therapy are reasonable. Don't hesitate to call or email us at Gulf Coast Veterinary Oncology! All the best, Kevin ===================================================== Kevin A. Hahn, DVM, PhD Diplomate ACVIM (Oncology) & Overall Nice Guy Gulf Coast Veterinary Specialists 1111 West Loop South, Suite 150 Houston, TX 77027 P: 713.693.1166 F: 713.693.1167 http://www.gcvs.com mailto:drhahn@gulfcoastvetspec.com