Fellow Westchester Medical Center Ardsley, New York, United States
Introduction : Primary Central Nervous System Lymphoma (PCNSL) is a rare but well-known form of extra nodal lymphoma which accounts for less than 3% of intracranial tumors. Ninety percent of PCNSL cases are diffuse large B cell lymphoma (DLBCL) and it involves various brain structures, most often located around the ventricles. CNS lymphoma presenting as a mass involving the hypothalamus is rare with data limited to very few case reports. The most common symptoms of hypothalamic lesions are diabetes insipidus (DI), hypernatremia and disorders of food intake, sleep, and behavior. Pituitary deficiencies are seen less often. Here we report a case of a PCNSL arising from the hypothalamus that presented with panhypopituitarism and diabetes insipidus.
Case(s) Description : We present a case of a 63-year-old woman with a past medical history of melanoma and lung cancer, both in remission, who presented from an outside hospital after a CT scan done for altered mental status revealed a suprasellar mass. Upon presentation to our hospital a brain MRI revealed a homogeneously enhancing mass centered along the floor of the anterior third ventricle and within the hypothalamus measuring up to 2.2 cm, as well as discontiguous intraventricular masses. Initial labs revealed a TSH of 0.307 mIU/L (0.35-4.70 mIU/L) with a Free T4 of 0.8 ng/dL (0.7-1.9 ng/dL), IGF-1 < 10 ng/mL (33-220 ng/mL), LH < 1.0 mIntlUnit/mL, FSH 1.15 mIntlUnit/mL, Total Estrogen level < 25 pg/mL. Prolactin level was 104.0 ng/mL (1.2-29.9 ng/mL), thought to be elevated due to the stalk effect. A 6 AM cortisol was 1.6 mcg/dL (3.7-19.4 ug/dL), with an ACTH level < 3.0 pg/mL (7.2-63.3 pg/ml) but the patient had received dexamethasone at the outside hospital, confounding the results. On the second day of admission, after the patient had been made NPO for a procedure, the serum sodium increased from 146 mEq/L to 158 mEq/L with acute worsening of her mental status, as well as hypothermia and bradycardia. In the setting of high volume, dilute polyuria and a urine osmolality of 165 mOsm/kg, she was diagnosed with diabetes insipidus. She was started on desmopressin with good response. She was also started on levothyroxine and steroids. A biopsy of the 2.2 cm third ventricle mass showed Diffuse Large B-Cell Lymphoma (DLBCL) and the patient was started on chemotherapy.
Discussion : Our patient presented with panhypopituitarism and DI in the setting of a hypothalamic mass. New onset DI and hypopituitarism should raise suspicion of a brain tumor affecting the hypothalamus and/or pituitary gland. These tumors are most often due to lung or breast cancer, leukemia, or lymphoma. Of note, our patient had a history of both lung cancer and melanoma so the diagnosis of DLBCL was surprising. Primary central nervous system lymphoma affecting the hypothalamus is rare and is difficult to diagnose by radiological appearance alone so a biopsy is necessary. Pituitary function may improve with chemotherapy, so close monitoring of hormone replacement is necessary during treatment.
