THU111 Diffuse Large B-Cell Lymphoma Pituitary Metastasis

Abstract

Abstract Disclosure: M.S. Martinez Cruz: None. C.J. Haas: None. S.Z. Bhat: None. Background: The Hypothalamus-Pituitary axis (HPA) is a rare location for metastasis of non-Hodgkin’s lymphoma. Case description: A 57-year-old woman presented to the emergency department with a one day of acute, severe fatigue, nausea, and anorexia. She reported a history of stage IIIB diffuse large B-cell non-Hodgkin's lymphoma (DLBCL) treated with R-CHOP three months prior, complicated by a recent recurrence in the lumbar spine requiring a short dexamethasone taper and radiation therapy two weeks prior to admission. On presentation, she remained hemodynamically stable with an otherwise unremarkable exam. Diagnostics revealed severe hypotonic hyponatremia suggestive of syndrome of inappropriate antidiuretic hormone (SIADH). CT scan of the head revealed thickening of the paramedian hypothalamic structures and the pituitary infundibulum. Subsequent pituitary MRI w/wo contrast demonstrated marked thickening and enhancement of the infundibulum with restricted diffusion, as well as T2/FLAIR hyperintensity and thickening in multiple hypothalamic areas concerning for HPA metastasis. Hormonal workup demonstrated panhypopituitarism for which she was started on hydrocortisone and levothyroxine. Lumbar puncture was performed with CSF flow cytometry revealing phenotypically abnormal monoclonal B-cells consistent with DLBCL leptomeningeal metastasis. Three days prior to induction chemotherapy, she developed massive polyuria, with a rapid increase in the serum sodium and markedly low urine-specific gravity consistent with acute diabetes insipidus (DI). Management included vasopressin, as needed, followed by standing doses of desmopressin. She was initiated on methotrexate and leucovorin chemotherapy. However, three week later, she developed acute onset diplopia, headache, nausea and vomiting, urinary and bowel incontinence, and fatigue. Follow-up pituitary MRI revealed progression of her known HPA metastatic disease, and she passed away one month later. Conclusion: This is an unprecedented case of metastatic DLBCL to the leptomeninges, hypothalamus, and pituitary infundibulum confirmed by CSF cytologic analysis that presented in the context of associated panhypopituitarism that manifested initially as SIADH followed by sudden DI. Abbreviations: R-CHOP: Rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone Presentation: Thursday, June 15, 2023