Prognostic significance of nuclear DNA content in phaeochromocytoma.

Nuclear DNA content of 27 phaeochromocytomas was measured by image analysis of thin sections and monolayer smears of nuclei extracted from thick sections (cytospins) using archival paraffin-embedded tissue blocks. Recurrence was assessed on the basis of clinical follow-up or urinary catecholamine levels. The mean follow-up was 5.0 years, with a range of 4 months to 15 years. Although it is not possible to differentiate accurately malignant tumours using DNA analysis, prediction of benign tumours is possible. Using thin sections, all tumours were benign when the percentage of cells with a DNA content of 2.5 c (2 c = diploid) was less than 40% and the DNA content of 5 c was less than 4%. Using the cytospin preparation, all diploid tumours were benign. Thus, patients with diploid tumours may be saved intensive long-term follow-up. Aneuploid and tetraploid tumours, however, continue to require careful lifelong follow-up.