Primary non-Hodgkin's lymphoma of the sciatic nerve followed by localization in the central nervous system: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: A unique case of primary non-Hodgkin's lymphoma of the sciatic nerve followed by multiple loci in the central nervous system is described. CLINICAL PRESENTATION: The lesion occurred in a 44-year-old immunocompetent man with a palpable mass in the left popliteal fossa and a 10-month history of progressive weakness and numbness of the left foot. The tumor was a diffuse large lymphoma of B-cell origin of an intermediate grade of malignancy according to the criteria of the International Working Formulation. INTERVENTION: Because diagnosis of the malignant lymphoma was performed on frozen section, resection of the nerve trunk was avoided. The patient was treated with radiotherapy and chemotherapy. At 6 months after the discovery, biopsy, and treatment of the sciatic nerve lymphoma, other lesions demonstrating the same histological features were observed in the central nervous system. The patient died 4 years and 2 months after presentation as a result of the central nervous system lesions and without clinical evidence of systemic extraneural localization. CONCLUSION: A review of the literature indicates that primary peripheral nerve lymphomas occur in the sciatic nerve. These cases, and the case described in our study, share common clinicopathological findings that justify discussing them separately as distinct entities.