RESUMO
INTRODUCTION AND IMPORTANCE: Solitary lymphomas of the peripheral nervous system are very rare and lymphomas of the sciatic nerve are uncommon, especially those arising from the proximal part of the nerve. This case report describes a rare presentation of solitary B cell Non-Hodgkin's Lymphoma arising from the proximal sciatic nerve that was managed via surgical excision. CASE PRESENTATION: A 28-year-old man experienced severe pain, motor and sensory issues in his right lower limb for a year. Magnetic Resonance Imaging identified a malignant peripheral nerve sheath tumour in the sciatic nerve involving S1 and S2 roots. No metastasis was found in CECT scans. Surgical resection via combined inguinal and gluteal approaches was followed by adjuvant chemoradiotherapy. Biopsy revealed diffuse large B-cell Lymphoma, non-Germinal Centre B-cell like subtype. Pain was reduced, and muscle power improved. CLINICAL DISCUSSION: Neurolymphomatosis (NL) is a rare condition where lymphoma cells invade nerves. It mostly involves peripheral nerves, particularly the sciatic nerve. Cases often present with painful neuropathy. Treatment varies, with surgery followed by chemotherapy and radiotherapy used in this unique case involving the pelvic sciatic nerve. Individual patient factors guide management due to limited case data. CONCLUSION: We present a unique case of neurolymphomatosis involving the proximal sciatic nerve, a rare occurrence. Surgical excision utilized a complex intra-abdominal and perineal approach, unprecedented in this context. This atypical presentation underscores the need to consider such cases in diagnosing unusual sensory motor neuropathies.