Metastatic Lymphoma of the Ulnar Nerve: A Case Report.

Metastatic peripheral nerve lymphomas are rare, often mimicking benign neurogenic tumors or neuropraxic injuries. While some report on the involvement of nerves in the upper and lower extremities, the majority of lymphomas involve the lower extremities, with the sciatic nerve being the most common. Furthermore, involvement of the ulnar nerve is exceedingly rare, with only four reported cases, each of which indicated a primary lesion. In this article, we report a unique case of recurrent B-cell lymphoma with metastatic disease of the ulnar nerve in a nonagenarian with a remote history of diffuse high-grade large B-cell lymphoma. The patient presented with 2 months of numbness, tingling, and weakness in her left ring and small fingers. Additionally, she reported a left distal forearm mass. Examination revealed sensory loss, atrophy, and clawing of the hand. Magnetic resonance imaging showed a mass involving the ulnar nerve, confirmed as lymphoma via biopsy. Treatment included radiotherapy and capsulodeses, given her desire for a functional return to her independent activities of daily living. She was satisfied with the outcome of her management. While uncommon, this case highlights the importance of considering metastatic disease as a presentation mimicking cubital tunnel syndrome for timely diagnosis and improved outcomes. By documenting this presentation, this report aims to raise awareness among orthopedic surgeons to enhance diagnostic and management strategies for similar cases of metastatic nature and advanced patient age.