Nonclassified Lymphoma as a Cause of Radial Nerve Paralysis in a Horse.
Authors: Barba Marta, Groover Erin S, Bailey Jessica, Cole Robert, Christopherson Peter, Cattley Russell
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Nonclassified Lymphoma as a Cause of Radial Nerve Paralysis in a Horse A 4-year-old Quarter Horse presented with acute non-weight-bearing lameness and shoulder swelling, with clinical examination revealing radial nerve paralysis; whilst musculoskeletal trauma was initially suspected, ultrasonography and fine needle aspiration cytology revealed an extensive large cell lymphoma originating in the deep pectoral muscles and extending into the thoracic inlet. Postmortem examination demonstrated that the neoplastic mass directly compressed the brachial plexus and its branches, mechanically inducing the radial nerve paralysis rather than traumatic injury. Although neoplastic nerve compression as an aetiology for radial nerve paralysis remains uncommon, this case highlights the importance of expanding differential diagnoses beyond typical musculoskeletal causes when presented with acute neurological deficits accompanied by soft tissue swelling in the shoulder region. Practitioners encountering cases of radial nerve paralysis with concurrent local swelling should consider advanced imaging and cytological investigation before attributing the condition to trauma alone, as early recognition—whilst unlikely to change immediate outcome in advanced cases—may facilitate more appropriate management decisions and allow discussion of prognosis with owners. The lack of age-related bias in tumour-induced nerve compression underscores that neoplasia warrants consideration across all age groups presenting with unexplained peripheral nerve deficits.
Read the full abstract on PubMed
Practical Takeaways
- •When evaluating acute radial nerve paralysis with shoulder swelling, include neoplasia in your differential diagnoses even in younger horses, not just trauma
- •Ultrasonography can help identify soft tissue masses in the shoulder region; fine needle aspirate cytology may confirm lymphoma diagnosis
- •Poor prognosis with nonclassified lymphoma affecting the brachial plexus typically leads to euthanasia; early recognition helps guide humane decision-making
Key Findings
- •A 4-year-old Quarter Horse presented with acute radial nerve paralysis secondary to locally invasive large cell lymphoma
- •Ultrasonography identified a heterogeneous mass extending from the point of shoulder to the thoracic inlet
- •Postmortem examination revealed the lymphoma extended into the brachial plexus, mechanically compressing all nerves in the region
- •Neoplasia should be considered in differential diagnoses for radial nerve paralysis regardless of patient age