INTRODUCTION: Solitary fibrous tumors (SFT) are uncommon spindle cell neoplasms, most frequently associated with serosal surfaces. Although benigh, because of their large size complete resection can present many challenges, particularly given their proximity to vital neighboring structures. We report a successful en-bloc resection of a massive mediastinal SFT which was compressing the inferior trachea and heart, via a clamshell (bilateral anterior thoracotomies and transverse sternotomy) incision.
CASE PRESENTATION: A 50-year-old male presented with a 1 year history of increasing dyspnea and lower extremity swelling. A chest x-ray revealed a large anterior mediastinal mass. Computed tomography (CT) confirmed the mass and noted that it extented from the confluence of the brachiocephalic veins to the diaphragm, significantly displacing both the carina and the heartposteriorly. Initial fine needle biospy was suspicious for thymoma which lead to concurrent induction radiation and chemotherapy consisting of carboplatin and taxol. Within 1 month, the patient had some improvement in his respiratory symptoms. Restaging CT imaging revealed minimal response to therapy with increased heterogenicity of the mass, suggestive of necrosis. Although there was slight interval decrease in size, both the heart and great vessels remained extrinsically compressed. A core needle biopsy of the mass at this time was consistent with a solitary fibrous tumor with CD 34 positive immunoperoxidase staining. Careful multidisciplinary planning between the anesthesiology and surgery team lead to the patient being anesthetized with ketamine; no paralytics were used. An awake fibroptic intubation was then performed. Using a clamshell incision, the mass was visualized to be adherent to the sternum, pericardium, and bilateral pleurae. There was no invasion into any mediastinal structures and the lesion was successfully resected en bloc. The tumor weighed 2.5 kilograms and measured 24cm X 14cm X 12cm. Histopathology revealed a solitary fibrous tumor, with bland spindle cells with extensive collagen deposition, rare mitoses, central hyalinization, but no tumor necrosis. All margins were free of tumor. The patient made an uneventful recovery and was discharged home on the 5th postoperative day.
DISCUSSIONS: SFTs are though to originate from the mesenchymal layer. The non-committed mesenchymal cells are able to differentiate into a number of tissues including blood vessels, cartilage, and bone. This diversity of differentiation accounts for the variable histologic patterns of SFT, which include: diffuse sclerosis, hemangiopericytoma-like and a patternless pattern. Since the morphology is so variable, it can be difficult to distinguish SFT from other spindle cell neoplasms such as mesthothelioma, smooth muscle tumors, neurogenic tumors, and fibrosarcoma. CD 34 is a useful immunohistochemical marker that stains for endothelium and vascular tumors, and also for most cases of SFT. SFTs typically present as intrathoracic, particularly plural-based lesions. Symptoms are a result of either local compression/invasion of adjacent thoracic structures (dyspnea, angina, cough) or paraneoplastic syndromes (hypoglycemia, weight loss, pulmonary osteoarthropathy). ∼10-15% of intrathoracic SFTs are malignant. Histologic criteria associated with malignancy include high cellularity, nuclear atypia, mitotic rate greater than 4 per 10 high-powered field, and necrosis. Patients with SFT require long-term follow-up as even histologically bland SFTs can recur. Tissue is required for diagnosis. Complete surgical resection is curative in most cases of benign SFT and nearly half of malignant SFT. There is no proven adjuvant therapy.
CONCLUSION: We present a case of a massive, mediastinal solitary fibrous tumor. Due to the large size and location of this tumor, a clamshell incision was used for adequate exposure and en-bloc removal. Preoperative measures were taken to prevent any airway collapse, including ketamine sedation with fiberoptic, awake intubation. Careful preoperative planning by both the surgeon and staff anesthesiologist are critical to the safe removal of large mediastinal SFTs.
DISCLOSURE: Dilip Nath, None.