Orbital rhabdomyosarcoma in an adult: a misleading presentation.

Rhabdomyosarcoma is the most common malignant mesenchymal tumor in children, whereas its occurrence in adults is exceptionally rare. When it occurs in this population, initial presentation with nonspecific rhinologic symptoms is unusual and may delay recognition of the underlying malignancy. We report the case of a 29-year-old woman who presented with progressive right-sided nasal obstruction and hyposmia, subsequently complicated by the rapid onset of unilateral proptosis. Cross-sectional imaging revealed a poorly circumscribed ethmoido-orbito-nasal mass with skull base erosion and orbital invasion, exhibiting aggressive radiologic features that initially raised suspicion for esthesioneuroblastoma. Histopathological examination ultimately confirmed alveolar rhabdomyosarcoma, staged as T2BN1M0 (IRS Group III). The patient underwent multimodal treatment combining VAC chemotherapy and conformal radiotherapy (45 Gy), resulting in an excellent clinical and radiologic response, with complete resolution of proptosis and significant visual recovery at 1-year follow-up. This case emphasizes the diagnostic challenges of adult orbital rhabdomyosarcoma with sinonasal extension and highlights the pivotal role of advanced imaging and histopathology in guiding accurate diagnosis and appropriate management. The rarity and unusual clinical presentation of this case underscore its value for publication.