FLOW CYTOMETRIC ANALYSIS DOES NOT RELIABLY DIFFERENTIATE BENIGN FROM MALIGNANT PHEOCHROMOCYTOMA

BACKGROUND AND OBJECTIVE The differentiation of benign from malignant phaeochromocytoma is difficult, We have examined whether the use of fl ow 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 p attern indicated benign disease. DESIGN AND PATIENTS DNA flow cytometr y was performed on phaeochromocytoma tissue from 36 patients (19 femal e, 17 male; mean age at presentation 39.5 years), The results were cor related 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 initia l removal of primary phaeochromocytoma, three have died from malignant recurrence, In these patients a diploid DNA cytometric pattern was ob served in two and an aneuploid pattern in one. Twenty-one patients are still alive, DNA cytometry showed a diploid pattern in the one patien t 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 develope d recurrent disease. Routine use of DNA flow cytometry did not reliabl y differentiate benign from malignant phaeochromocytoma. Prolonged cli nical and biochemical follow-up is still necessary for all patients wi th this condition.