Predictors of malignancy in primary aldosteronism.

INTRODUCTION: Primary aldosteronism (PA, also Conn syndrome) is a benign disease in majority of cases. However, malignant transformation has been described. Present study reports on three cases of aldosterone producing adrenocortical carcinoma (APAC) in comparison to patients with benign PA. PATIENTS AND METHODS: Data of patients undergoing adrenalectomy for benign PA were compared to patients with APAC. Retrospective chart analysis was performed. All patients received spironolactone for 6-8 weeks preoperatively. RESULTS: Seventy-four patients underwent adrenalectomy for PA between 1994 and 2011. Three of them revealed an APAC. Patients with APAC presented with a significantly lower serum potassium level (1.7 mmol/l vs. 3.4 mmol/l, p = 0.001) and significant larger tumors (5.2 vs. 1.8 cm, p = 0.002). In addition, aldosterone/renin (A/R) ratio 675 in patients with APAC as compared to 74 in patients with benign PA (p = 0.0001). Sixty-eight of 71 patients with benign PA underwent minimal invasive surgery, whereas all three patients with APAC were operated conventionally. All patients with APAC developed disease recurrence 6-18 months postoperatively. CONCLUSION: Tumor size >4 cm and a very high A/R ratio seems to predictors of malignancy in patients with PA. If these criteria are present, open adrenalectomy should be performed instead of endoscopic procedure.