P-080 PITUITARY METASTASIS PRESENTING WITH SEVERE HYPONATREMIA AND RAPID CLINICAL DETERIORATION

Abstract Introduction Metastases to the pituitary gland are rare complications, usually presenting with diabetes insipidus, headache, visual impairment, and, less commonly, secondary adrenal insufficiency. We present a case of pituitary metastasis of unknown origin with a rapidly progressive course. Clinical Case A 66-year-old male presented to the emergency department in December 2024 with severe headache unresponsive to analgesics and progressive somnolence. Blood pressure was 160/100 mmHg. Cranial CT revealed a pituitary macroadenoma, and labs showed severe hyponatremia (Na⁺ 111 mmol/L). He was started on IV hydrocortisone (100 mg) and hypertonic saline, and underwent urgent surgery. Postoperatively, he was referred to endocrinology with complaints of nausea, vomiting, drowsiness, and abdominal pain. He denied hypoglycemia, hypotension, polyuria, or visual disturbances. He lost 5 kg over the past month. Physical examination revealed GCS of 14 with mild somnolence; abdominal tenderness was present without defence or rebound. Preoperative labs showed panhypopituitarism He received hydrocortisone 50 mg q6h and levothyroxine 50 mcg daily. After steroid replacement, hyponatremia improved, but he developed diabetes insipidus characterized by polyuria (200 cc/kg/hour) and low urine specific gravity (1.004). Despite therapy, abdominal pain persisted, and follow-up tests showed rising transaminases and tumor markers (Table-2). Abdominal CT revealed bilateral adrenal masses (5.5 cm, 3.5 cm). PET-CT demonstrated multiple hypermetabolic lymph nodes, adrenal masses suspicious for malignancy, a lung mass with pleural effusion, diffuse thyroid uptake, and peritoneal carcinomatosis. Histopathology of the pituitary lesion was consistent with neuroendocrine carcinoma. SATB2 staining was positive in scattered tumor cells, suggesting a possible lower GI origin (Table-3). Primary site evaluation was planned; however, the patient deteriorated rapidly, required ICU transfer, and died from progressive multiorgan failure in January 2025. Conclusion Although pituitary metastases are rare, metastasis should be considered when pituitary insufficiency is detected. Severe hyponatremia, diabetes insipidus at diagnosis, advanced age, and rapid clinical deterioration may represent alarming signs requiring prompt evaluation and intervention.Table 1:Anterior Hypophysis Hormon Results Table 2:Other Laboratory Results Table 3:Pathology Markers for HypopyhsisNo findings supporting a pituitary origin were identified. Scattered SATB2 positivity suggests a possible metastatic tumor, most likely from the lower gastrointestinal tract. Correlation with clinical and radiological findings is recommended.