A PUZZLING DIAGNOSIS: UNUSUAL LARYNGEAL CARCINOMA PRESENTING AS PARANEOPLASTIC SYNDROME

Abstract

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: The Syndrome of Inappropriate Antidiuretic Hormone (SIADH) is one of the most common causes of euvolemic hyponatremia. The most common malignancy associated with SIADH is small cell lung cancer. We present a case of a patient with SIADH secondary to well differentiated squamous cell carcinoma of the vocal cords. CASE PRESENTATION: A 62-year-old Caucasian male with a history of alcohol abuse and 80 pack-year smoking history presented with recurrent hyponatremia. He was initially admitted to the ICU for altered mental status due to hyponatremia of 111 which was thought to be a combination of beer potomania/SIADH/low solute intake. He required hypertonic saline boluses twice and a one dose of DDAVP to prevent overcorrection, along with fluid restriction with an improvement of Na to 132. (Image 1) Chest CT was obtained that did not reveal any malignancy. He was discharged with fluid restriction and follow up with his PCP. At his follow up, he was found to have again developed severe hyponatremia of 112. He was admitted again to the ICU for appropriate normalization of sodium, required isotonic saline and then fluid restriction. SIADH was confirmed by low Serum Osmolality at 245mosm/kg, high Urine osmolality of 502mosm/kg, Urine sodium of 41mEq/l,and normal serum Potassium of 4.3mEq/l along with low serum uric acid of 3.4mg/dl. Upon review of the CT chest with the radiologist he had some density on his left aryepiglottic fold. Upon closer discussion with him, he endorsed progressive hoarseness for the past year to the point of losing his voice. He also lost about 20 pounds over the last year, with a 10-pound weight loss over the past month. CT neck with IV contrast showed a 4.5cm laryngeal mass (Image 2) and direct laryngoscopy and microscopic laryngoscopy with biopsy of the tumor on the left vocal cord with multiple biopsies taken of the terminal vocal cords finally revealed squamous cell carcinoma. He is scheduled to follow up with oncology, ENT and radiation oncology after a PET scan for tumor staging to decide on further treatment with concurrent chemotherapy and radiation. DISCUSSION: There is a possible relationship between the tumor mass burden and the severity of the hyponatremia. This has been shown in another laryngeal carcinoma but was not seen with recurrence of the tumor.[1] The mechanisms leading to the associated hyponatremia could have been related to tumor ADH productions or other factors yet unknown.[2] CONCLUSIONS: SIADH is well known to occur with squamous cell lung cancer. Other types of squamous cell carcinomas are known to cause SIADH as a paraneoplastic syndrome, particularly squamous cell carcinoma of the tongue.[3] It has not been well documented to be from squamous cell carcinoma of vocal cords. Reference #1: Talmi YP, Hoffman HT, McCabe BF (1992) Syndrome of inappropriate secretion of arginine vasopressin in patients with cancer of the head and neck. Ann Otol Rhinol Laryngol 101:946-949 Reference #2: Roth Y, Lightman SL, Kronenberg J. (1994). Hyponatremia associated with laryngeal squamous cell carcinoma. Eur Arch Otorhinolaryngol 251: 183-185 Reference #3: Zohar Y, Talmi YP, Finkelstein Y, Nobel M, Gafter U (1991) Syndrome of inappropriate antidiuretic hormone secretion in cancer of the head and neck. Ann Otol Rhinol Laryngol 100:341-344 DISCLOSURES: No relevant relationships by Sofia Adamidi, source=Web Response no disclosure on file for Steven Lamontagne; No relevant relationships by Preeyanka Sundar, source=Web Response