Sciatic nerve neuropathy due to infiltrating of a high grade B-cell lymphoma is a very rare situation and has not often been reported. We report a case with a previous history of indolent lymphoma who presented with isolated sciatic nerve neuropathy and was found to have diffuse large B cell lymphoma involving the sciatic nerve. Although the current case is not a primary sciatic nerve lymphoma given the systematic involvement shown on MRI and PET/CT scan, the case represents a neurolymphomatosis of the sciatic nerve given the direct invasion of the lymphoma cells into the sciatic nerve. Due to the rarity of this condition, we subsequently reviewed related literatures.