Leiomyosarcoma of the hypopharynx: a case report.

Cases of leiomyosarcoma in the head and neck are very rare with only four reports of a leiomyosarcoma originating in the hypopharynx. A rare case of leiomyosarcoma of the hypopharynx is described. A 62-year-old woman, who had experienced slight difficulty of swallowing and hoarseness, visited our hospital. A smooth-surfaced tumor was found extending from the postcricoid to an area in the left pyriform sinus, and the vocal cord on the left side was fixed. Imaging studies, including FDG-PET CT imaging showed the tumor in the postcricoid, but no distinguishable distant metastases. A total laryngectomy with a left-lobe thyroidectomy was performed. Since no metastases of the regional lymph nodes were found by imaging, a neck dissection was not performed. Dense infiltration by spindle-shaped and/or round-like cells was observed histologically as the predominant growth pattern. In immunohistochemical staining, the tumor was positive for desmin and muscle actin, while it was negative for myoglobin, myogenin, cytokeratin, and S-100 protein. Electron microscopic examination did not show Z banding and sarcomeres. Those features lead to the diagnosis of a leiomyosarcoma. No recurrence has been found at 1 year after the surgery. Immunohistochemical staining and electron microscopic examination are essential for a definite diagnosis of leiomyosarcoma.