Adrenal tumors Abstract. The term 'adrenal tumor' describes benign and malignant mass lesions of the adrenal gland, including primary adrenal tumors and metastases from extra-adrenal origin. With the widespread use of imaging technique, adrenal tumors have become increasingly detected as 'incidentalomas'. The detection of an adrenal tumor raises two questions: Is the mass malignant? Is the mass hormonally active? Whereas the evaluation for malignancy is based on specific imaging characteristics (imaging phenotype), a targeted clinical examination and specific biochemical tests are required to assess for hormonal secretion. An adrenal mass 4 cm), and in cases with non-conclusive evaluation for malignancy or hormonal activity, the decision for further management has to be made on an individual basis. A minimally invasive surgical approach may be considered in adrenal tumors < 6 cm and without local infiltration of adjacent structures. Both laparoscopic (transabdominal) and retroperitoneoscopic techniques are possible. The surgical outcome depends on the surgeon's experience. A close interdisciplinary collaboration is mandatory in the evaluation and treatment of adrenal tumors.