Endocrine Abstracts

Introduction: Olfactory neuroblastoma causing syndrome of inappropriate antidiuretic hormone (SIADH) as paraneoplastic syndrome is very rare. There have been only 10 cases with antidiuretic hormone (ADH) producing olfactory neuroblastoma in the literature. The syndrome is due to ectopic production of protein hormones, hormone precursors, or hormone-like substances by the tumor tissue. Here, we report the case of olfactory neuroblastoma associated with SIADH.

Observation: Patient S.D., 25 years old, with a history of inappropriate ADH secretion syndrome (SIADH) under NaCl, had consulted for unilateral left nasal obstruction evolving for five months. Examination revealed a fleshy, richly vascularized tumor mass filling the entire left nasal cavity. The right nasal cavity and the cavum were free. A biopsy was performed and the diagnosis was an inverted papilloma. The CT scan of the facial mass revealed a 23×41 mm hyperdense nasosinusal tumor formation with blowing calcifications extending to the maxillary sinus and to the homolateral ethmoidal cells coming in contact with the papyraceous lamina and the roof of the ethmoid. MRI of the facial mass showed a left maxillary tissue process of 40×25×45 mm. The walls of the left maxillary sinus are thinned but continuous. Retentional filling of the maxillary and left frontal sinuses and no brain abnormalities. The patient underwent a middle meatotomy, anterior and posterior ethmoidectomy and left sphenoidotomy by endonasal approach removing the tumor. The immediate postoperative course was simple. The extemporaneous examination was in favor of a massive tumor, non vascular, without histological signs of malignancy. The final anatomopathological examination concluded to an olfactory aesthesioneuroblastoma stage II of Hyams. The patient was proposed for postoperative RT, but the patient did not reconsult.