[Hereditary study on bilateral parotid tumors of the same histotype]

Bilateral tumors of the same histotype occur rarely in opposite organs. These include hereditary diseases such as retinoblastoma and Wilm's tumor. Bilateral tumors of the same histotype also occur in the parotid glands. A study was performed to determine if there is a possibility that hereditary tumors are included in such cases. Two cases of bilateral parotid tumors, one of pleomorphic adenoma and one of adenolymphoma were reported, and 59 cases reported between 1942 and 1990 with clear times of onset which underwent histological examinations were analyzed. The main histotypes were adenolymphoma in 50.8% (30 cases), pleomorphic adenoma in 27.1% (16 cases), acinic cell tumor in 13.6% (8 cases). Onset of the tumors was simultaneous in 43% of the adenolymphomas. The sex and age at onset showed the same trends as in unilateral cases for each histotype. Among parotid tumors, the percentage of bilateral onset is 1-2%, and when adenolymphomas which show the highest incidence among such tumors were considered from the standpoints of multiplicity, simultaneous onset and the fact that they are benign, the possibility that hereditary diseases are included in the aforementioned 43% was suggested.