Vertebral angiosarcoma in a horse.

The research paper revolves around the case of a horse diagnosed with vertebral angiosarcoma, an uncommon type of vascular tumor. The study is conducted based on data collected from the Animal Health Diagnostic Laboratory, Michigan State University over a span of nearly ten years.

Introduction and Case Background

• The study examines a unique case of an 18-year-old Quarter Horse gelding with vertebral angiosarcoma, a type of vascular tumor. Vascular tumors are reportedly rare in horses, with only 16 cases identified in a batch of 27,604 equine cases over a nine-year period.
• These 16 vascular tumor cases were further classified into hemangiomas and hemangiosarcomas or angiosarcomas. The focus of this report is one such case of vertebral angiosarcoma.
• The horse had shown symptoms of head-lift difficulty, which over a period of two weeks, progressed into ataxia (loss of partial or complete control over bodily movements) and recumbency (inability to rise).
• A myelogram – a diagnostic imaging study targeting the spinal canal and its contents – pointed to a mass affecting the spinal cord at the level of the fourth cervical vertebra (C4). The horse was euthanized and a necropsy was carried out post-mortem.

Observations and Findings

• During the necropsy, a sizeable soft mass was observed in the extradural space ventral to the spinal cord and within the vertebral canal of C4. The mass was predominantly dark red and yellow, which were present free-floating in the space.
• The vertebral canal of the same vertebra (C4) was affected by an infiltrate of the same soft dark red tissue, which had elevated the surrounding periosteum and resulted in depression and bone-softening at the canal’s floor.
• The vertebral body of C4 was observed to be sclerotic (hardened), dotted with red and yellow, with all usual cancellous (spongy) bone invisible. Both right and left transverse foramina of C4 were filled with the same dark red tissue.
• The same tissue was found ventral to the C4 vertebral body, appearing to be a dark red, soft mass. The researchers didn’t find grossly visible signals of the lesions extending beyond the C4 level at this stage.

Further Analysis and Conclusion

• The tissues specimens were processed for hematoxylin and eosin staining, a popular technique in histology for observing tissue and cell structure in detail.
• The histological study revealed the presence of a large, anaplastic (abnormally simple), multinodular vascular neoplasm with closely-packed blood-filled vessels of varying sizes lined by plump endothelial cells.
• The vascular spaces within these masses contained plump cells with indistinct cell borders and abundant pale eosinophilic, vacuolated cytoplasm. The nuclei of these cells ranged from vesicular to coarsely clumped and contained a single nucleolus, which is typical in tumor cells.
• The study confirms the presence of vertebral angiosarcoma in the horse, contributing to the limited knowledge and acknowledgment of this rare condition in the field of veterinary oncology.