Pheochromocytoma nuclear pattern analysis by flow cytometry

Flow cytometric nuclear DNA analyses were performed on paraffin-embedded tissue samples taken from 39 patients with pheochromocytoma treated between 1981 and 1992. The Hedley technique was used for measurement of nuclear DNA contents. Only 30 cases out of the 39 tumors were available for the determination of DNA ploidy analyses. Ten cases (33.3%) showed a diploidy pattern, 8-cases (27%) showed an aneuploidy pattern and 12 cases (40%) revealed a tetraploidy pattern. Four cases of malignant pheochromocytoma with regional or distal metastasis had been noted during a mean follow-up period of 4.75 years. All these four cases showed tetraploidy nuclear pattern with vascular invasion on pathological examination, which was statistically significant (p < 0.001) in differentiation between benign and malignant pheochromocytoma. About one third of patients with tetraploidy appeared to have malignant tendencies and this was statistically significant (p < 0.05). None of the patients with either diploidy or aneuploidy pattern had disease progression. The location of the tumor (adrenal vs. extra-adrenal) and 24 hours urine total vanillylmandelic acid (VMA) amounts were not significantly different from the diploid, aneuploid or tetraploid groups. These results suggested that nuclear DNA ploidy pattern is an important independent, and useful prognostic factor for patients with pheochromocytoma.