[A site of origin histopathological study on parapharyngeal space tumors. A review of 76 cases].

Tumors of the parapharyngeal space are said to account for 0.5% of all head and neck tumors, and are thus relatively rare. We performed histopathological examination of 76 tumors of the parapharyngeal space in patients hospitalized at the International University of Health and Welfare, Mita Hospital Head and Neck Oncology and Surgery center for 6 years from July 2005 to June 2011. There were 35 men and 41 women; the patients ranged in age from 15 to 78 years with a median age of 44. We performed preoperative CT and MRI, aspiration biopsy cytology (fine needle aspiration [FNA]) and postoperative histopathology diagnosis. There were 69 benign tumors (90.8%), and 7 malignant tumors (11.8%). Among the benign tumors were 32 schwannomas (42.1%) and 28 pleomorphic adenomas (36.8%). A total of 26 tumors of prestyloid origin were pleomorphic adenomas (93.8%), and 28 tumors of poststyloid origin were schwannomas (87.5%); all 7 malignant tumors (100%) were of prestyloid origin. There were 55 patients who underwent preoperative FNA, and the proper diagnosis rate was 70.9% (39/55 case). Preoperative imaging seemed to be very useful for predicting the histopathology. Furthermore, it would be desirable for FNA to be performed preoperatively for tumors of prestyloid origin, in consideration of the likelihood of such tumors being malignant. We think that there is room for improvement in the accurate FNA diagnosis rate.