Co-existence of two aneuploid stemlines in benign adenomas. A report of three cases with stemline heterogeneity.

The co-existence of 2 or more aneuploid stemlines (DNA multiploidy) has been described in malignant human neoplasms and such cancers have often been found to be associated with a poor prognosis. Here 3 benign human adenomas with 2 co-existing aneuploid stemlines are described. Despite DNA stemline heterogeneity and large DNA indices up to 2.8 none of the adenomas recurred or gave rise to metastases after a simple excision during the follow-up of 8, 10 and 11 years. Two adenomas were hormonally active. Marked cellular atypia and frequent mitoses were seen in 1 of the adenomas but the other 2 tumours had little atypia. The present cases indicate that DNA stemline heterogeneity may occur in benign adenomas, and not even the presence of 2 aneuploid stemlines with greatly increased nuclear DNA content can be regarded as a conclusive sign of malignancy.