Radiation-Induced Leiomyosarcoma of the Ethmoid Sinus

Abstract

This high–grade radiation–associated sarcoma involves the paranasal sinuses, anterior skull base, and orbit of the patient's only remaining eye. Leiomyosarcomas are exceedingly rare, high–grade tumors of the head and neck with the potential for distant metastases. Before local and regional management is planned, absence of distant disease must be established. At my institution, a bone scan and computed tomography of the chest, abdomen, and pelvis would be performed to rule out distant disease. For patients with a soft–tissue sarcoma, wide resection and reconstruction followed by radiation offer the best chance of a disease–free survival. In principle, orbital invasion dictates that exenteration be performed in most cases. Unfortunately, this patient has only one eye. The patient must be involved in the decision making, but I would attempt to salvage his vision at the expense of a close surgical margin. However, the patient must be fully prepared for an intraoperative decision to remove the orbit if necessary. Extension of the tumor through the cribriform plate requires a combined intracranial–transfacial surgical approach. In such situations, my preferred method is an anterior craniofacial resection through a bifrontal craniotomy and lateral rhinotomy with a subciliary extension. The resection would include the anterior skull base, ethmoid sinuses, maxillary suprastructure, and the medial wall and floor of the orbit. The involved intraorbital contents would also be resected en bloc. I would make every attempt to preserve the globe and its neurovascular integrity. The patient will not suffer from diplopia even with limited extraocular movement. The palate would be left intact. The likelihood of cervical metastases is low, and I would perform no neck dissection in the absence of clinical disease. The reconstructive goals include reconstitution of dural integrity and restoration of the orbital–facial contour. Postoperative complications should be minimized. A pericranial flap based on the supratrochlear and supraorbital vessels can be used to support the anterior duraplasty. The facial contour can be maintained using calvarial bone grafts to replace the bony orbit. A free vascularized myogenous flap (my preference is the latissimus dorsi muscle) would be positioned to fill the soft–tissue defect, to provide further dural protection, and to vascularize the bone grafts. Postoperative radiation is fundamental to this case, in particular because a close margin is expected if vision is to be preserved. Planning should begin preoperatively in discussion with the radiation oncologist. This patient previously received orthovoltage radiation of 30 Gy, likely delivered using the POP (parallel opposed pair) technique. The dosage to the brain was likely limited, and reradiation is possible. At our center, the patient would be considered for intensity modulated radiation therapy to limit radiation to the retina and optic nerve while delivering more than 60 Gy to the surgical bed. However, postoperative proton–beam radiation has distinct advantages over conventional radiation. In such a case, I would seek an opinion from a center with this capability before surgery. John Yoo M.D. Department of Otolaryngology Head and Neck Oncology–Reconstructive Microsurgery University of Western Ontario London Health Sciences Centre 800 Commissioners Road East London, Ontario, N6A 4G5 Canada John.Yoo@lhsc.on.ca