Embryonal Rhabdomyosarcoma of the Orbit

Abstract

Orbital rhabdomyosarcoma in children is a relatively rare disease. There have been only 30 known cases reported in Japan. A case of orbital rhabdomyosarcoma with long-term survival was reported. An 11-year-old boy was admitted because of rapidly progressive exophthalmos, chemosis and visual disturbance of the right eye. Right carotid angiography demonstrated a walnut-sized tumor stained heterogeneously in the supero-lateral portion of the orbit which was fed by engorged external carotid branches as well as by the ophthalmic artery. A total removal of the tumor was performed through the frontozygomatic approach. Histological examinations revealed small cells with scanty cytoplasm distributed in the myxomatous matrix. Cross striations were stained in some tumor cells which had a long cytoplasmic process. He recieved 5, 500 rads by Linac irradiation postoperatively. His visual acuity improved from nearly blind to 0.15. Four years after the operation there is no sign of any tumor recurrence. It is very difficult to diagnose orbital rhabdomyosarcoma preoperatively because a definitive diagnosis must be based on histological findings. Cross striation which is often recognized in so-called racket cells with eosinophilic cytoplasm in light-microscopy and/or myofilaments in the tumor cells by electronmicroscopy are proof that the tumor is of myogenic origin.