Primary central nervous system lymphoma with initial presentation of cerebral salt-wasting syndrome shifting to syndrome of inappropriate antidiuretic hormone secretion: A case report

Abstract

Background. Primary central nervous system lymphoma (PCNSL) is a rare form of non-Hodgkin lymphoma which may affect brain parenchyma. Hyponatremia can be present as one of the complications, either due to neuronal injury arising from in-situ tumor and/or surgical resection (resulting in cerebral salt wasting syndrome/CSWS) or indolent, slowly progressing and often asymptomatic one as a consequence of ongoing chronic illness (so-called syndrome of inappropriate antidiuretic hormone/SIADH). Differentiating between the two is critical, since each diagnosis has a starkly different treatment approach which may exacerbate one another. Case presentation. Herein, we reported a case of a 48-year-old immunocompetent male who presented with diplopia, hallucination, imbalance, and dizziness, later to be diagnosed with PCNSL on multiple brain regions. He suffered from symptomatic hyponatremia post-surgically as a result of CSWS which in turn responding well to intensive dose of desmopressin acetate and fluid replenishment. However, as the disease progressed, hyponatremia also relapsed but was refractory to the same treatment approach. After subsequent investigations, patient was known to have SIADH. Treatments tailored to SIADH including fluid restriction and administration of hypertonic saline as well as tolvaptan lead to stabilization of sodium levels and significant clinical improvements. Conclusion. Post-operative hyponatremia in the setting of a PCNSL continues to be a complex issue. It underscores the importance of careful clinical assessment, monitoring, and the need for flexibility in diagnosis and management strategies. Furthermore, it highlights the challenges of distinguishing between CSWS and SIADH, two conditions with similar laboratory findings but divergent management approaches. Recognizing the subtleties in clinical presentation and responding appropriately can greatly influence patient outcomes. The rising incidence of PCNSL in immunocompetent individuals also needs a heightened awareness and understanding of its presentations and potential post-operative complications among clinicians.