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Clinical Challenge
November 2015

Hyponatremia and Right Maxillary Sinus Mass

Author Affiliations
  • 1The University of Texas Health Science Center at Houston, Houston
  • 2Children’s Mercy Hospital and Clinics, Kansas City, Missouri
  • 3University of Kansas Medical Center, Kansas City, Missouri
JAMA Otolaryngol Head Neck Surg. 2015;141(11):1021-1022. doi:10.1001/jamaoto.2015.2314

A teen-aged boy with a recent history of resolved streptococcal pharyngitis presented with dizziness, vomiting, unstable gait, and headaches of 2 weeks’ duration. Laboratory evaluation revealed a sodium level of 109 mEq/L. Rapid correction to 136 mEq/L occurred, resulting in lethargy, aphasia, and ataxia. He was diagnosed as having idiopathic syndrome of inappropriate antidiuretic hormone secretion (SIADH). Magnetic resonance imaging (MRI) demonstrated an abnormal signal within the basal ganglia and insular cortex. A 2.5 × 1.5 × 1.8-cm mass was found in the superior right maxillary sinus with extension into the infundibulum (Figure, A). Computed tomographic (CT) scans of the sinuses without intravenous contrast demonstrated that the mass had calcifications. Owing to persistent hyponatremia (sodium level, 125-130 mEq/L) and an identifiable lesion, the patient was taken to the operating room for biopsy. He underwent a maxillary antrostomy with near-complete removal of the mass. Over the subsequent 2 weeks, the hyponatremia resolved and the patient was left with slight dysarthria and difficulties with fine-motor movements. The submucosa contained a small, round, blue-cell tumor growing in circumscribed lobules and nests separated by vascularized fibrous stroma. The neoplastic cells had uniform, small, round nuclei with scant cytoplasm. Cells were arranged in a pseudorosette pattern (Figure, B). The nuclei demonstrated dispersed, salt and pepper nuclear chromatin and inconspicuous nucleoli. The cells were surrounded by a neurofibrillary matrix. There were prominent microcalcifications. No mitotic figures were seen. The tumor cells were diffusely positive for immunohistochemical marker synaptophysin (Figure, C). Results from cytokeratin staining were negative (Figure, D).

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