Endocrine Abstracts

Introduction: Although the syndrome of inappropriate antidiuretic hormone (SIADH) has connection with various malignant tumors, the pituitary metastasis of malignant tumors are generally associated with diabetes insipidus.

Case report: A 59 years old male patient presented to emergency service with frequent syncope attacks, nausea, loss of appetite and fatigue that began 2 weeks prior to admission. Marked obtundation was found on physical examination. The patient had not any history or symptom consistent with lung disease. However, other physical examinations including vital signs were normal. Serum sodium was 100 mEq/l, potassium 4.6 mEq/l, creatinine 0.81 mg/dl, urea 29 mg/dl, uric acid 2.1 mg/dl, glucose 101 mg/dl, TSH: 0.01U/l (0.4–4), free T4: 0.94 ng/dl (0.9–1.8), free T3: 1.7 pg/ml (1.8–3.8), FSH: 0.3 mIU/ml, LH: 0.1 mIU/ml, total testosterone <20 ng/dl (230–400), cortisol: 6 mcg/dl, ACTH: 6 pg/ml, IGF-1: 68 ng/ml, urine sodium 126 mmol/l and plasma osmolality was 240 mOsmol/kg, on laboratory examination. The patient was diagnosed as panhypopituitarism and SIADH. The low serum cortisol levels did not respond to short synacthen test. A pituitary mass of 30×16×18 mm in size was found on pituitary MRI. A complet right side vision loss was present on visual field examination. The patient underwent pituitary surgery. The histopathological and immunohistochemistry results revealed SCLC metastasis. A mass of 41×36 mm in size was determined on the apicoposterior segment of the left upper lung lobe on chest CT and widespread metastasis was found on FDG/PET CT, including pituitary gland. The result of lung needle biopsy was consistent with small cell lung cancer. The SIADH in this case was thought to be associated with SCLC. The patient died two months after first diagnosis.

Conclusions: Although associated with low survival rates, the presence of metastasis should always be thought in elderly and middle aged patients diagnosed with non-functioning pituitary tumors, irrespective of clinical presentation.