Combined Endoscopic Endonasal and Sublabial Approach to Giant Solitary Fibrous Tumor Involving the Maxilla, Central Skull Base, and Parapharyngeal Spaces: A Case Study

Objectives To report a rare case of a giant solitary fibrous tumor presenting with progressive dysphagia and dysphonia. To describe a successful surgical approach combining endoscopy and sublabial facial degloving.

Results A 63-year-old man presents to otolaryngology clinic with a 1-year history of an ill-fitting upper denture, left-sided nasal congestion, and left eye epiphora. A CT sinus revealed a large 9 cm × 11 cm heterogeneous soft tissue mass centered in the left maxillary sinus extending into the left pterygopalatine fossa, infratemporal fossa, masticator space, and parapharyngeal space. There was bony erosion of the medial, lateral, and posterior maxillary sinus walls as well as the floor of the left orbit. The posterior margin of the lesion abutted the internal carotid artery but appeared to be separated by a fat plane. A transnasal incisional biopsy confirmed a solitary fibrous tumor with positive immunohistochemical staining of beta-catenin, STAT 6, bcl-2, and smooth muscle actin. The patient was initially consented for combined endoscopic and open transcervical approach with possible free flap reconstruction. The tumor was methodically and sequentially debulked endoscopically through the left nasal cavity. A complete extended left ethmoidectomy was performed to access the medial orbital wall and floor which revealed a fairly well-defined capsular plane throughout as well as completely intact orbit. Next, a transpterygoid approach to the middle cranial fossa floor exposed erosion of the pterygoid processes. Tumor debulking continued into the infratemporal fossa and the anterior aspect of the parapharyngeal space. An open approach via a sublabial incision was necessary for adequate surgical visualization of the remaining tumor into the parapharyngeal space. The tumor was easily resected from the carotid sheath and ultimately delivered through the maxillotomy. It was ultimately determined that a free flap reconstruction was not necessary in anticipation of secondary healing of the sinonasal defect and the gingival incision was closed primarily. Final pathology confirmed a solitary fibrous tumor originating in the left maxillary sinus. The patient did remarkably well after an extensive operation reporting minimal pain, complete resolution of symptoms, and no signs of residual disease 4 weeks postoperatively.

Conclusion Solitary fibrous tumors are a rare type of mesenchymal neoplasm that usually occurs in the pleura but has been described in almost every organ of the body. The tumor is characterized by the proliferation of thin-walled vessels and collagen-producing cells. Surgical resection with wide margins is the treatment of choice because these tumors tend to be locally invasive and have the potential to become malignant.