Histologic Features of a Solitary Fibrous Tumor in the Region of Oral Cavity and Maxillofacial Complex with Recurrence and Distant Metastasis: a Rare Case Report

Abstract

Introduction/Objective Solitary fibrous tumor (SFT) is an uncommon mesenchymal neoplasm, and may involve many anatomic locations. Approximately 0.6% of SFTs in the oral cavity and maxillofacial complex may recur and/or develop distant metastasis. Here we report a case of SFT in oral cavity with local recurrence and distant metastasis. Methods/Case Report The patient was a 66-year-old male with a past medical history of left buccal mass status post excision with an unclear diagnosis in a foreign country 6 years ago. He presented with a recurrence of the left buccal mass. Computerized tomography (CT) of the head and chest demonstrated a 9 cm expansile mass centered in the left pterygopalatine fossa and a 1.7 cm mass in left upper lobe of the lung, respectively. Biopsy of the lung mass was performed first and displayed a hypercellular mesenchymal tumor, composed of spindle cells arranged in vague short fascicles, and scant fibrous stroma with thin-walled and staghorn-like vasculature. The tumor cells had mild nuclear atypia with 5 mitoses/10 high power fields. No necrosis is identified. There were trapped benign pneumocytes and bronchial epithelial cells in the tumor. The tumor is positive for CD34, CD99, Bcl-2 and STAT6 immunostains. The large left buccal mass was biopsied later and showed similar morphology. The diagnoses of metastatic SFT in the lung and recurrent SFT were rendered, respectively. Results (if a Case Study enter NA) NA. Conclusion The histologic findings of the recurrent SFT and the pulmonary metastasis are similar in our case. Although marked cellular atypia and necrosis are not observed in either tumor, other features including the large size of recurrent tumor, hypercellularity, and increased mitotic activity are associated with malignant behavior in this report, and warrant the need for long-term follow-up.