Primary synovial sarcoma of the larynx in a 14-year-old boy diagnosed by immunohistochemistry and fluorescence in situ hybridization: a rare case report

Synovial sarcoma (SS) is an aggressive soft tissue tumor, which occurs predominantly in young adults. The SS can arise in almost any part of the body, especially in the lower extremity. The SS of head and neck accounts for 1.9-3.5% of all SS, however, the mass appears very extremely rare in the larynx. We report a case of a biphasic SS in the larynx. A 14-year-old boy appeared without apparent inducement with hoarseness, dyspnea, fever, cough, hemoptysis, pharyngeal foreign body sensation, dysphagia, odynophagia and other symptoms since nearly one month ago. The patient underwent partial laryngectomy and performed a wide surgical excision of the tumor with a free margin. Pathological examinations of the tumor specimen revealed an encapsulated and firm tumor lesion. The grayish-white to dark-brown mass was 8x6x4 cm, arising from the left of aryepiglottic fold. Histological examination showed the characteristic histomorphological features such as biphasic pattern of short spindle cells and epithelioid cells, including glandular differentiation. Immunohistochemically, staining for vimentin, bcl-2 and calponin were typically positive in the spindle tumor cells. Staining for CK was typically positive in the epithelioidtumor cells. Staining for EMA, CD99 and TLE-1 were typically positive in both the epithelioid and spindle tumor cells. The presence of SYT-SSX fusion gene from chromosomal translocation was detected by FISH in this case. Two months postoperatively, the patient received local radiotherapy. Combined treatment may be effective and the patient is alive without tumor recurrence in radiological and clinical examination after 18 months of follow-up.