Endocrine Abstracts

Primary CNS lymphoma (PCNSL) accounts for 0.85% - 2.0% of primary brain tumours. PCNSL arises in periventricular regions of the corpus callosum, with hypothalamic involvement less commonly. While cases have been reported in the literature, cranial diabetes insipidus (CDI) secondary to PCNSL is a rare phenomenon. We present this case series of three patients from our institution diagnosed with CDI and panhypopituitarism in the context of PCNSL.

Cases: 1. 38-year-old female presenting with an eight-week history of increasing fatigue, reduced oral intake, polyuria and severe hypernatraemia. She was diagnosed with panhypopituitarism and CDI. MRI Brain showed multifocal enhancing mass-like lesions in the hypothalamus, lateral ventricles and medulla. Histology confirmed a high-grade B cell lymphoma. She died shortly from her disease. 2. 70-year-old man presenting following two presyncopal episodes, on a background of increasing fatigue. Subsequently, he developed progressive bulbar signs and required intubation for respiratory failure. Panhypopituitarism and CDI were diagnosed with polyuria and hypernatraemia developing following glucocorticoid replacement. CNS imaging showed hypothalamic destruction, periventricular disease and medullary involvement, which were highly suggestive of CNS lymphoma. Sadly the patient died before tissue diagnosis. 3. 42-year-old presented with progressive visual disturbance and evolving right frontal mass. Biopsy confirmed high-grade B cell follicular lymphoma. CT PET showed extensively disseminated metastases, with dural extension of frontal mass. Evolving polyuria and polydipsia were noted during an inpatient stay, and a diagnosis of CDI and panhypopituitarism was made. The patient is currently awaiting consideration for a stem cell transplant following recurrence post chemotherapy.

Discussion: While PCNSL presenting with CDI is rarely encountered in clinical practice, it is important to consider it in the differential. Our case series highlights the complexities and high mortality associated with diagnosing PCNSL and secondary endocrinopathies. More data is needed to ascertain if CDI represents an independent poor prognostic indicator in PCNSL.