Nonclassified Lymphoma as a Cause of Radial Nerve Paralysis in a Horse.

The research addresses an unusual case of radial nerve paralysis in a horse, triggered by a non classified lymphoma. Typically considered rare, this case puts forth the possibility that neoplasia, or the abnormal growth of cells, can be a cause of radial nerve paralysis, irrespective of the age of the horse.

Case Presentation

• The horse under study was a 4-year-old American Quarter breed with acute non-weight-bearing lameness in its right limb. It also exhibited swelling around the right shoulder area.
• Upon examining the horse physically, the veterinary team discovered that the horse was suffering from radial nerve paralysis. However, the cause of the disease was unknown.
• Initially, musculoskeletal trauma was suspected to be the primary cause of the nerve paralysis.

Diagnostic Approach

• In order to discern the true cause of the paralysis, an ultrasonography was performed on the horse’s right shoulder region. This medical imaging technique uses high-frequency sound waves to visualize the internal structure of the body.
• On inspection, the veterinarians identified a heterogenous mass going from the point of the shoulder to the thoracic inlet.
• A fluid sample was collected from the mass using a fine needle and sent for cytological analysis.
• The results of the cytological analysis indicated the presence of large cell lymphoma in the samples, providing hints towards the cause of the horse’s radial nerve paralysis.

Interpretation and Conclusion

• Based on the large cell lymphoma cells identified from the mass, the medical team concluded that locally invasive neoplasia – the abnormal proliferation of cells, in this case, was the probable cause of the radial nerve paralysis.
• Considering the bleak prognosis and expected quality of life, the horse was euthanized.
• Postmortem examination confirmed the lymphoma. It revealed that the large cell lymphoma extended from the deep tissues of the right pectoral muscle group to the thoracic inlet and pleural cavity, as well as the right brachial plexus.
• It was concluded that the mass in the region of the brachial plexus encompassed and mechanically compressed the nerves causing radial nerve paralysis.
• Although Neoplasia leading to radial nerve paralysis is usually rare, this case emphasizes its inclusion in differential diagnosis, independent of the age of the horse.