Aneuploidy in salivary gland adenomas.

The occurrence of abnormal nuclear DNA content in major salivary gland adenomas is not well known and its correlation with tumor recurrence has not been documented previously. From 1987 to 1991, 119 consecutive major salivary gland adenomas were operated on at Turku University Central Hospital. These tumors were analyzed by flow cytometry and 100 (84%) were found to be diploid, 12 (10%) near-diploid and 7 (6%) aneuploid with DNA indexes > 1.15. The mean proliferation rate measured as a percentage of cells in the S-phase fraction was 2.5 +/- 1.6%. The histological slides were then blindly reclassified according to current World Health Organization classification. As a result histological classification was changed in 3 tumors: malignant cells were found in 2 aneuploid tumors and 1 diploid neoplasm. Preoperative cytological fine-needle aspiration biopsy had been considered as possibly malignant in 2 of these cases. Among all case material 10 specimens were recurrent tumors; although the tendency to recur depended on the extent and adequacy of the surgery performed, multiple recurrences were associated with non-diploid tumors.