Bilateral Proptosis as an Unusual Presentation of Adult-Onset Alveolar-Type Rhabdomyosarcoma of Ethmoid Sinus: A Case Report.

Rhabdomyosarcoma (RMS) exhibits varying degrees of clinical manifestations, and one of the determining factors is its primary site of origin. Ocular proptosis is an infrequent presentation of parameningeal RMS. The growing tumor in spacious environments such as air-filled sinuses can obscure its early detection, leading to late disease intervention. Among the four subtypes (embryonal, leiomyomatous, sclerosing and spindle cell, and alveolar), the predominant type of RMS in the paranasal sinuses is alveolar. The incidence in adult-onset RMS is relatively low compared with those of children. We herein present a rare case of a 23-year-old man with an unusual presentation of bilateral proptosis from alveolar RMS of the ethmoid sinus. In contrast to our patient, most reported cases of ocular involvement in RMS turned out to be unilateral and responded poorly to treatment. Despite the aggressive behavior of the adult-onset alveolar subtype in comparable reports, our case shows an excellent outcome. Negative fusion status has been recognized in recent studies as a molecular feature inclined toward a favorable outcome in alveolar RMS. The integration of molecular prognostic factors to risk stratification could be advantageous in determining different prognoses and proper management for an individual patient.