Syndrome of inappropriate antidiuretic hormone secretion associated with head neck cancers: review of the literature.

In a minority of patients with malignant tumors, signs and symptoms develop that cannot be explained on the basis of the mass effect produced by the primary tumor or its metastases, or production of a hormone normally associated with the tissue type that has given rise to the malignant tumor; these peculiar symptom complexes are known as paraneoplastic syndromes, and may be divided into endocrinologic, dermatologic, hematologic, neurologic, and osteoarticular manifestations. In the head and neck region in particular, the syndrome of inappropriate antidiuretic hormone production (SIADH, or Schwartz-Bartter syndrome) is a well-recognized form of paraneoplastic syndrome that may accompany head and neck malignancies. Most of such tumors are squamous carcinomas, with lesser numbers of olfactory neuroblastomas, small cell neuroendocrine carcinomas, adenoid cystic carcinomas, and undifferentiated carcinomas; sarcoma was reported in only a single instance. The lesions associated with the development of SIADH have most often been located in the oral cavity, and less often in the larynx, nasopharynx, hypopharynx, nasal cavity, maxillary sinus, parapharyngeal space, salivary glands, and oropharynx. Key features of SIADH include serum hypo-osmolality; an unexpectedly high urinary specific gravity; an absence of edema or dehydration; normal adrenal, thyroid, and renal function; hyponatremia; and an elevation of plasma vasopressin.