[Perineural spreading along the trigeminal nerve in a patient with primary intracranial malignant lymphoma: a case report].

We report a rare primary intracranial malignant lymphoma which spread along the trigeminal nerve through the skull base foramen. The patient was a 50-year-old woman, who was diagnosed as having a primary intracranial malignant lymphoma in the right temporal lobe and had undergone an operation and radiation 5 years previously. The tumor was reduced in size and no recurrent tumor could be detected for 5 years. The patient complained of left face swelling and CT scan revealed a large mass in the pterygopalatine fossa. MRI revealed the recurrent tumor in the left Meckel's cave with extension into the cavernous sinus. The tumor extended through the foramen ovale into the pterygopalatine fossa, through the superior orbital fissure into the orbital cavity and through the infraorbital fossa into the face subcutaneously. Biopsy of the subcutaneous tumor was carried out and the pathological diagnosis was malignant lymphoma, B cell type, which was identical with the initial tumor. MRI revealed the enlarged trigeminal nerve and 3D-CT revealed the enlargement of the infraorbital fossa and the foramen ovale. We suspected that primary intracranial malignant lymphoma had recurred in the left Meckel's cave and the tumor had spread along the peripheral three divisions of the trigeminal nerve. Perineural spreading along the trigeminal nerve passing through the skull base in patients with nasopharyngeal carcinoma is not rare, but this rarely occurs in the case of intracranial tumors.