Flow cytometric analysis does not reliably differentiate benign from malignant phaeochromocytoma

BACKGROUND AND OBJECTIVE The differentiation of benign from malignant phaeochromocytoma is difficult, We have examined whether the use of flow cytometric determination of nuclear DNA content would be useful as a predictor of malignant behaviour in patients with phaeochromocytoma as some previous studies had suggested that a diploid cytometric DNA pattern indicated benign disease. DESIGN AND PATIENTS DNA flow cytometry was performed on phaeochromocytoma tissue from 36 patients (19 female, 17 male; mean age at presentation 39.5 years), The results were correlated with clinical outcome after prolonged follow-up. MEASUREMENTS DNA histograms were constructed following nuclear suspension analysis. RESULTS Of 26 patients followed up for more than 5 years after initial removal of primary phaeochromocytoma, three have died from malignant recurrence, In these patients a diploid DNA cytometric pattern was observed in two and an aneuploid pattern in one. Twenty-one patients are still alive, DNA cytometry showed a diploid pattern in the one patient who developed recurrent phaeochromocytoma 4 years after removal of a primary tumour. CONCLUSION In this study, three of nine patients with an apparently benign diploid cytometric pattern subsequently developed recurrent disease. Routine use of DNA flow cytometry did not reliably differentiate benign from malignant phaeochromocytoma. Prolonged clinical and biochemical follow-up is still necessary for all patients with this condition.