Benign parotid oncocytoma with the chromosomal abnormality trisomy 7.

This report concerns the first cytogenetical study of a benign salivary gland oncocytoma. The cultured tumor was studied in five consecutive preparations. The first three were dominated by cells with a normal karyotype. In the two subsequent preparations a hyperdiploid stemline characterized by trisomy 7 had taken over. Trisomy 7 has previously been observed in a number of different, benign, premalignant and malignant conditions. We interpreted trisomy 7 in the salivary gland oncocytoma, as in these other conditions, to be a neoplasia-related, probably primary, gross chromosomal change and not an expression of aging or comparable events in normal cells.