Imaging findings of a hemangiosarcoma in a cervical vertebra of a horse

Introduction : A hemangiosarcoma is a malignant tumor of the vascular endothelium that rarely occurs in horses. In this species it mainly occurs in the musculoskeletal and respiratory systems.[1-4] This tumor metastasizes rapidly and clinical signs are determined by tumor location. Objective : This case report describes the clinical, imaging and pathological findings in a gelding with a hemangiosarcoma in the cranial cervical region. Materials and methods : An 18-year-old gelding was presented with recent, abrupt onset of ataxia. Transcranial magnetic stimulation (TMS) was performed and magnetic motor evoked potentials (MMEP) were measured in front- and hind limbs. Native and post-contrast (cisterna magna; Iohexol (Omnipaque 240), 20 ml/100 kg body weight) lateral radiographic projections of the cervical region were obtained. This was followed by a computed tomographic (CT) myelography, using a single-slice helical CT scanner. The horse was euthanized and a post-mortem examination was performed. Results : TMS revealed delayed responses in all limbs suggesting a lesion in the cervical spinal cord. The MMEP had abnormal morphology and clearly prolonged latency times, with the delay being pronounced on the left compared to the right. Radiographically, osteolytic lesions were present in the third cervical vertebra (C3). The cervical myelogram revealed an image of spinal cord swelling at the level of C3. The CT images showed osteolytic lesions and circumferential thinning of the contrast column due to extra-dural compression at the cranial cervical region. These findings were compatible with an aggressive bone lesion compressing the spinal cord. Primary or secondary neoplasia and osteomyelitis were considered in the differential diagnosis. Because of the poor prognosis, the horse underwent euthanasia. Post-mortem histopathological diagnosis was a hemangiosarcoma involving the cervical vertebrae and the epidural space. Conclusions : This report demonstrates the additional value of CT myelography on extend and exact location of cervical vertebral compressive lesions horses. This information can be useful for prognosis, biopsy and planned surgery of these lesions. References 1. Johns et al. (2005) Hemangiosarcoma in 11 young horses. J. Vet. Intern. Med. 19, 564-570. 2. Reinachter (1978) Hemangioendotheliome in der skelettmuskulatur eines pferdes. Berl. Munch. Tierartztl. Wochenschr. 91, 121-123. 3. Valentine et al. (1986) Intramuscular hemangiosarcoma with pulmonary metastasis in a horse. J. Am. Vet. Med. Assoc. 188, 628. 4. Van Pelt et al. (1972) Multiple hemangiosarcomas in the tarsal synovial sheath of a horse. J. Am. Vet. Med. Assoc. 161, 49.