Discussion

Neurological symptoms in patients with intrathecal pumps are often, and reasonably, attributed to complications related to the pump, however, this case demonstrates that a broader differential diagnosis should also be considered early to prevent permanent consequences.
While central nervous system lymphomas (CNSL) are rare, accounting for 4-6% of all lymphomas, they are associated with a poor prognosis. Primary central nervous system lymphoma (PCNSL) is associated with a slight male predominance, immunosuppression such as HIV and is confined to the brain, cranial nerves, eyes, leptomeninges and/or spinal cord (8). Secondary central nervous system lymphoma (SCNSL) occurs in up to 5% of high grade and <3% of indolent lymphoma patients. The risk of SCNSL is increased in lymphomas involving the paranasal sinuses, testes, marrow or adrenals and is now assessed by the CNS lymphoma score (CNS-IPI) (9). Adverse prognostic features for CNSL include SCNSL, age >60 years, elevated lactate dehydrogenase (LDH), elevated CSF protein and involvement of deep regions of the brain (10). PCNSL is usually classified as a High grade Diffuse large B cell lymphoma (DLBCL) of non-germinal centre cell origin with up to 16% having CARD11 mutations affecting the NFKB pathway (11).
As seen in this case, the symptoms can vary but the a transverse myelopathy can be induced by direct tumour infiltration, intravascular infiltration or most suspect in this case an immunogenic paraneoplastic syndrome. The histology of Non-Germinal centre B cell (N-GCB) subtype High grade DLBC determines a high risk individual despite an CNS-IPI score of 3. Treatment should involve CNS penetrating regimes with potential consolidation with an Autologous Stem cell transplant (ASCT), provided the patient tolerates and attains remission.
This case also highlights the difficulty in diagnosis when biopsy is not amenable and must be made on CSF flowcytometry, MRI findings and PCR IGHV rearrangement (12). It also showcases the dilemma of steroids use without histology which the patient responded to remarkably until the final presentation and tonsillar mass. In general, investigation of a patient suspected of having paraneoplastic syndrome might fail to reveal the tumour until it becomes symptomatic, typically 3-13 months later (13). This patient showed myelopathy as presenting symptom of DLBC, which was initially believed to be related to the intrathecal pump, and therefore was only diagnosed after 1 month of presenting to the clinic.