Adrenal incidentaloma: Clinical characteristics and comparison between patients with and without extra-adrenal malignancy

Adrenal incidentaloma (AI) is frequently found in patients with a history of malignancy and, as such, is not always considered a true incidental finding. Objective: To compare the short-term clinical and biochemical behavior of adrenal incidentalomas between oncology and non-oncology patients. Design: Retrospective comparative case series of 100 consecutive patients with adrenal incidentaloma, followed from 1995 to 2005 in the endocrinology clinic of a tertiary university medical center. Main outcome: A history of malignancy was present in 32 patients. Median follow-up was 24 months. Mean tumor size was 24±10 mm. Endocrine evaluation yielded functional abnormalities in 12.2% (subclinical Cushing's 7.4%, Cushing's syndrome 1.1%, hyperaldosteronism 1.3%, pheochromocytoma 3.6%). During follow-up, adrenal function remained unchanged in all patients, but tumor growth was seen in 12.5%. Compared to the non-oncology patients, the oncology group had a higher mean age (67.5±9.6 vs 59.4±1.3 yr, p=0.001) and greater tumor growth (23.3% vs 7%, p=0.035), with no significant differences for tumor size, functional abnormalities, and extent of change in tumor size. Surgery was performed in 9 patients (3 oncologic) and revealed metastasis in one. None of the other patients had clinical or radiological findings suggesting adrenal malignancy. Conclusion: Our study suggests a similar clinical behavior of adrenal incidentaloma in oncology and non-oncology patients. More studies are needed to assist clinicians in selecting oncology patients with AI for whom a more conservative approach can be recommended.