Adrenal incidentaloma - follow-up results from a Swedish prospective study

To examine the risk of developing adrenal carcinomas and clinically overt hypersecreting tumours during short-term follow-up in patients with adrenal incidentalomas.

229 (98 males and 131 females) patients with adrenal incidentalomas were investigated in a prospective follow-up study (median time 25 months; range 3-108 months). The patients were registered between January 1996 and July 2001 and followed until December 2004. Twenty-seven Swedish hospitals contributed with follow-up results.

Diagnostic procedures were undertaken according to a protocol including reinvestigation with computed tomography scans after 3-6 months, 15-18 months and 27-30 months, as well as hormonal evaluation at baseline and after 27-30 months of follow-up. Operation was recommended when the incidentaloma size increased or if there was a suspicion of a hypersecreting tumour.

The median age at diagnosis of the 229 patients included in the follow-up study was 64 years (range 28-84 years) and the median size of the adrenal incidentalomas when discovered was 2.5 cm (range 1-8 cm). During the follow-up period, an increase in incidentaloma size of > or =0.5 cm was reported in 17 (7.4%) and of > or =1.0 cm was reported in 12 (5.2%) of the 229 patients. A decrease in size was seen in 12 patients (5.2%). A hypersecreting tumour was found in 2% of the hormonally investigated patients: Cushing's syndrome (n = 2) and phaeochromocytoma (n = 1). Eleven patients underwent adrenalectomy, but no cases of primary adrenal malignancy were observed.

Patients with adrenal incidentaloma had a low risk of developing malignancy or hormonal hypersecretion during a short-term follow-up period.