Case Report: When obstructive sleep apnea is not benign—nasopharyngeal rhabdomyosarcoma in a 3-year-old

Obstructive sleep apnea (OSA) is common in children and is most frequently associated with adenotonsillar hypertrophy. However, similar symptoms may occasionally reflect more serious upper airway pathology. We report a previously healthy 3-year-old boy who presented with snoring, mouth breathing, witnessed apneas, and persistent nasal obstruction in the setting of an acute viral upper respiratory illness. Initial flexible nasopharyngeal endoscopy was limited by copious secretions and poor cooperation, with no obvious mass identified. The subsequent development of epistaxis prompted repeat endoscopic evaluation, which revealed a left-sided nasopharyngeal mass. Imaging demonstrated an aggressive parameningeal lesion with skull base erosion and extension into the cavernous sinus. Histopathological examination, supported by positive immunohistochemical staining for desmin, myogenin, and MyoD1, confirmed embryonal rhabdomyosarcoma. The patient received VAC-based chemotherapy and proton radiotherapy, with subsequent tumor regression and stable findings on long-term imaging follow-up; he remained clinically well approximately four years after completion of therapy. This case highlights the potential for diagnostic anchoring when common symptoms of pediatric OSA coexist with apparently benign conditions such as adenotonsillar hypertrophy or an acute respiratory infection. Incomplete nasopharyngeal visualization should not be considered reassuring when symptoms persist or evolve. The emergence of red-flag features, particularly epistaxis, progressive nasal obstruction, or failure to improve as expected, should prompt timely reassessment and consideration of cross-sectional imaging to exclude an underlying structural lesion.