A Case of Alveolar Rhabdomyosarcoma of the Ethmoid Sinus Invading the Orbit in an Adult

PURPOSE A case study and literature review of alveolar rhabdomyosarcoma (RMS) in an adult. METHODS A 48-year-old male patient presented at our clinic complaining of proptosis that had persisted for 2 weeks in his left eye. A computed tomography (CT) scan revealed a destructive soft-tissue mass in the left ethmoid sinus with invasion of the left orbit and compression of the medial rectus muscle. Endoscopic intranasal biopsy revealed alveolar RMS. Conservative debulking and orbital wall decompression were performed. RESULTS Immunohistochemical testing was positive for desmin, S-100, and smooth muscle actin (SMA), supporting the diagnosis of RMS. Since ipsilateral cervical and spinal metastasis was detected, systemic treatment was administered simultaneously. CONCLUSIONS Although rarely found in adults, RMS should be considered in the differential diagnosis of orbital tumors. Immunohistochemical analysis plays an important role in the definitive diagnosis of RMS.