Dna ploidy of pheochromocytoma on cytology specimen by image analysis.

Pheochromocytoma usually shows prominent nuclear atypia, but the presence of such atypical cells is known to be an unreliable predictor of malignancy. DNA ploidy of pheochromocytomas has been analyzed by flow cytometry or photospectrometry on paraffinem-bedded tissue, but the results were controversial. We performed DNA analysis on cytology specimens of 11 pheochromocytomas using an image analysis system. All tumors had a mixed pattern of a large population of diploid cells and a small population of polyploid cells. DNA content correlated with nuclear size, and larger cells had more DNA content. Such larger tumor cells had polyploid nuclei, such as 4 C, 8 C, 16 C, and 32 C, in both malignant and benign pheochromocytomas. The larger polyploid nuclei may result from difficulty of duplication at the mitotic phase of the cell cycle.