Case report: Solitary mass of the sciatic nerve confirmed as a primary extranodal manifestation of diffuse large B-cell lymphoma in a geriatric patient.

Background: Neoplastic lesions affecting peripheral nerves are rare in the general population and, most often, are benign peripheral nerve sheath tumors. However, a minority of lesions represent high-grade malignancies associated with a poor prognosis, such as malignant peripheral nerve sheath tumors (MPNSTs). Very rarely, these tumors represent peripheral non-nerve sheath tumors (PNNSTs), such as hematological neoplasms that impair nerve function.