SYNDROME OF INAPPROPRIATE ANTIDIURETIC-HORMONE SECRETION ASSOCIATED WITH HEAD AND NECK CANCERS - REVIEW OF THE LITERATURE

In a minority of patients with malignant tumors, signs and symptoms de velop that cannot be explained on the basis of the mass effect produce d by the primary tumor or its metastases, or production of a hormone n ormally associated with the tissue type that has given rise to the mal ignant tumor; these peculiar symptom complexes are known as paraneopla stic syndromes, and may be divided into endocrinologic, dermatologic, hematologic, neurologic, and osteoarticular manifestations. In the hea d and neck region in particular, the syndrome of inappropriate antidiu retic hormone production (SIADH, or Schwartz-Bartter syndrome) is a we ll-recognized form of paraneoplastic syndrome that may accompany head and neck malignancies. Most of such tumors are squamous carcinomas, wi th lesser numbers of olfactory neuroblastomas, small cell neuroendocri ne carcinomas, adenoid cystic carcinomas, and undifferentiated carcino mas; sarcoma was reported in only a single instance. The lesions assoc iated with the development of SIADH have most often been located in th e 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.