Hypertrophic Osteopathy TUMOR TIDBITS, A BIWEEKLY EMAIL NEWSLETTER FROM GULF COAST VETERINARY ONCOLOGY Number 83; January 10, 2003. ======================================================================= THIS WEEK'S TUMOR TIDBIT: Hypertrophic Osteopathy. ======================================================================= ANNOUNCEMENTS 1] We're still actively recruiting patients for our clinical therapy trials. If you have a dog with hemangiosarcoma or lymphoma, please check our web site or call us for eligibility criteria. 2] Check our web site regularly for updated information on protocols and client education handouts. Coming up this Spring is our Annual Patient Celebration of Life and increased office hours in our San Antonio location. ======================================================================= HYPERTROPHIC OSTEOPATHY WHAT'S IN THE TEXTBOOKS Hypertropic osteopathy (HO) is disease that causes high peripheral blood flow and periosteal new bone proliferation along the diaphyseal region of long bones, often beginning in the distal phalanges, metacarpal bones, and metatarsal bones. The pathogenesis is speculative. Theories include chronic anoxia, obscure toxins, hyperestrogenism, and autonomic neurovascular reflex mechanisms mediated by afferent branches of the vagus or intercostal nerves. HO is considered a manifestation of a primary disease process. It occurs more commonly in dogs than cats. The age of highest frequency is 8 years, which coincides with the peak incidence of pulmonary neoplasms. The mean age is 5.6 years for dogs with nonneoplastic lung lesions. Large- breed dogs between 1-2 years of age with embryonal rhabdomyosarcoma have been reported. SIGNS & SYMPTOMS * Listlessness * Reluctance to move * Enlargement of the distal portion of the extremities EXAMINATION FINDINGS * Lame, sore, and painful limbs * Extremities are enlarged and firm to the touch but not edematous * Swelling predominantly below level of elbow and stifle joints extending distally to toes DIFFERENTIAL DIAGNOSES * Primary and metastatic lung tumors (esophageal sarcoma; embryonal rhabdomyosarcoma of the urinary bladder; adenocarcinoma of the liver or prostate gland, thoracic and abdominal mesotheliomas; metastatic neoplasia--bones not symmetrically affected). * Nonneoplastic thoracic conditions-- pneumonia, heartworm disease, congenital/acquired heart disease, bronchial foreign bodies, Spirocerca lupi infestation of esophagus, and focal lung atelectasis. In osteomyelitis, the bones may not be symmetrically affected and generally edematous; presence of lysis; history of penetrating trauma or systemic infection. DIAGNOSTIC FINDINGS * Dependent on the underlying cause, most laboratory results are normal. * Serum alkaline phosphatase may be high in some dogs. * Radiographs of the extremities--bilaterally symmetric extensive, rough, periosteal new bone formation on diaphyseal region of long bones; buds of periosteal new bone project outward from the cortex and perpendicular to its long axis and may form around the entire circumference of the bone; joints are not affected. * Radiographs of the thoracic and abdominal cavities should be taken to rule out various systemic disorders. * Ultrasound can be used to help identify and differentiate primary lesions. TREATMENT CONSIDERATIONS * In most situations, the condition will resolve with definitve treatment of the underlying primary cause. * Unilateral vagotomy on the side of a lung lesion, incising through the parietal pleura, subperiosteal rib resection, or bilateral cervical vagotomy have all been suggested as methods of treatment. * Glucocorticoids (i.e., prednisone) may be used to improve clinical signs and reduce the extent of swelling. * Analgesics as needed. PROGNOSIS & FOLLOW-UP * Bony changes may take several months to regress. * Prognosis is guarded to poor due to the common occurrence of neoplastic causes. * HO is an indicator of other disease processes; therefore, its diagnosis is important in recognizing the need for further diagnostic tests to identify the primary cause. SYNONYMS * Hypertrophic pulmonary osteopathy (HPO) * Hypertrophic pulmonary osteoarthropathy (HPOA) * Hypertrophic osteoarthropathy (HOA) WHAT DO WE DO AT GULF COAST? * This is a condition we commonly observe in dogs with metastatic osteosarcoma. * Radiotherapy of the affected long bones (every 2 weeks) may result in pain relief. * Fentanyl patches have been helpful in palliation of pain. * Regression of metastatic lesions (partial response, not complete) using aggressive IV chemotherapy (Carboplatin, Adriamycin, Cisplatin, Mitoxantrone - depending on prior chemotherapy usage in that pet) may be observed and resolve HO. * In a patient without prior therapy, treatment of the underlying neoplastic condition is helpful. With extensive prior therapy (chemotherapy), response times are poor. ======================================================================= As always, we hope this info helps and don't hesitate to call or email us Gulf Coast Veterinary Oncology! Kevin A. Hahn, DVM, Phd, Diplomate ACVIM (Oncology), drhahn@gcvs.com Janet K. Carreras, VMD, Diplomate ACVIM (Oncology), drcarreras@gcvs.com Glen K. King, DVM, MS, Diplomate ACVR (Radiology & Radiation Therapy), drking@gcvs.com Gulf Coast Veterinary Diagnostic Imaging & Oncology 1111 West Loop South, Suite 150, Houston, TX 77027 P: 713.693.1166 F: 713.693.1167 W: www.gcvs.com