Primary cauda equina lymphoma confirmed by autopsy: A case report

Compared with those involving the central nervous system, lymphomas involving the peripheral nervous system, namely neurolymphomatosis, are extremely rare. Neurolymphomatosis is classified as primary or secondary; the former is much rarer than the latter. Herein, we present an autopsied case of primary cauda equina lymphoma (PCEL), a type of primary neurolymphomatosis, with a literature review of autopsied cases of PCEL as well as primary neurolymphomatosis other than PCEL (non-PCEL primary neurolymphomatosis). A 70-year-old woman presented with difficulty walking, followed by paraplegia and then bladder and bowel disturbance. On magnetic resonance imaging, the cauda equina was diffusely enlarged and enhanced with gadolinium. The brainstem and cerebellum were also enhanced with gadolinium along their surface. The differential diagnosis of the patient included meningeal tumors (other than lymphomas), lymphomas, or sarcoidosis. The biopsy of the cauda equina was planned for a definite diagnosis, but because the patient deteriorated so rapidly, it was not performed. Eventually, she was affected by cranial nerve palsies. With the definite diagnosis being undetermined, the patient died approximately 1.5 years after the onset of disesase. At autopsy, the cauda equina was replaced by a bulky mass composed of atypical B-lymphoid cells, consistent with diffuse large B-cell lymphoma (DLBCL). The spinal cord was heavily infiltrated, as were the spinal/cranial nerves and subarachnoid space. There was metastasis in the left adrenal. The patient was finally diagnosed postmortem as PCEL with a DLBCL phenotype. To date, there have been a limited number of autopsied cases of PCEL and non-PCEL primary neurolymphomatosis (nine cases in all, including ours). The diagnosis is, without exception, B-cell lymphoma including DLBCL, and the histology features central nervous system parenchymal infiltration, nerve root involvement, and subarachnoid dissemination (lymphomatous meningitis). Metastases are not uncommon. All clinicians and pathologists should be aware of lymphomas primarily involving the peripheral nervous system.