Pathology of adrenal tumours: recent advances

Changes in the nomenclature and classification of adrenal gland diseases are the result of advances in understanding the pathogenesis, germline susceptibility and the clonal-neoplastic nature of diseases of the adrenal gland. Although numerous classification systems have been proposed, the Weiss system remains the standard for distinguishing benign from malignant adult adrenal cortical tumours, but the Helsinki system and the reticulin algorithm are proving to be increasingly useful in difficult cases. Subtypes of adrenal cortical neoplasms, such as myxoid and oncocytic, as well as those occurring in children require special consideration as their classification systems are different from those for standard adult adrenal cortical neoplasms. The importance of proliferative activity is central to the evaluation of adrenal cortical neoplasms. As for primary unilateral aldosteronism, CYP11B2 immunostain is increasingly studied to identify sites of aldosterone production with the hope of finding staining patterns predictive of clinical outcomes. Awareness of the clonal-neoplastic nature of adrenal cortical nodules and underlying germline susceptibilities has also advanced the classification of adrenal cortical nodular disease. For the adrenal medulla, pheochromocytomas (intra-adrenal paragangliomas) are all regarded as malignant tumours as they all have potential for metastases and are often associated with genetic susceptibilities.