Pituitary metastasis of lung neuroendocrine carcinoma: case report and literature review

Metastasis to the pituitary gland is an unusual situation in clinical practice, but the frequency thereof is increasing due to the increased survival of cancer patients, and greater availability of imaging. In most cases, they are found between the sixth and seventh decades of life, as determined in image examination of patients with known malignant neoplasm, but, generally, asymptomatic with respect to pituitary involvement. The most common primary sites are breast in women and lung in men. We present the case of a 64-year-old patient with clinical visual changes, polyuria, polydipsia, and decreased level of consciousness whose tests showed pan-hypopituitarism, hypernatremia and low urine specific gravity, and extensive mass in sellar region. Diabetes insipidus was confirmed and treated, corticotrophic and thyroid deficits were corrected and then the patient underwent resection by transsphenoidal surgery. The histopathological and immunohistochemistry analysis revealed pituitary metastasis of lung neuroendocrine tumor. Subsequently, a chest CT scan showed pulmonary mass consistent with primary neoplasm. Despite the water and electrolyte correction and intravenous glucocorticoid replacement, the patient continued to show decreased level of consciousness due to compression of the brain stem by the pituitary mass, evolving to death. The purpose is to call attention to the differential diagnosis of invasive lesions of the sellar region, mainly in individuals over 50 years and/or when associated with diabetes insipidus, as it may be a case of metastasis, although there is no known primary neoplasm.