Adrenal incidentalomas: experience from a retrospective study in a Chinese population

With no generally accepted criteria for preoperative differential diagnosis between benign and malignant adrenal lesions, management of adrenal incidentalomas, especially those between 4 and 6 cm, remains controversial.

Clinical details, radiological diagnosis, laboratory examination, intervention measures, and follow-up data were noted in 152 patients with adrenal incidentaloma hospitalized at a tertiary referral hospital in eastern China between July 1999 and February 2008. Pathologic diagnoses were analyzed in surgical cases.

Of 143 surgical patients, the mean pathologic size of the tumors was 5.6 ± 3.2 cm (range 0.5 to 22.0 cm). The final benign pathologic diagnosis mainly included adrenocortical adenoma (31.3%), pheochromocytoma (18.8%), myelolipoma (16.7%), and ganglioneuromas (9.0%). The incidence of malignancy was 6.9%. Based on the size criterion of 6 cm, there was a significant difference between malignant and benign tumor groups (P=0.007), but based on the size criterion of 4 or 5 cm, there was no significant difference between the two groups.

In our experience, the incidence of malignancy in adrenal incidentalomas was generally low, but relatively high in adrenal incidentalomas >6 cm. Nerve cell tumors constitute a significant number of cases of adrenal incidentaloma. Overtreatment of nonfunctional incidentalomas <4 cm remains frequent in China, and close follow-up for this group is recommended. Factors such as radiologic characteristics and patient concern should be taken into account for nonfunctional incidentalomas between 4 and 6 cm (not including 6 cm), for which laparoscopic adrenalectomy is a reasonable option.