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Adrenal glands are small paired retroperitoneal organs that are essential to life. While some adrenal glands are “cappers” and are positioned over the kidney’s upper pole, others are “cradlers” that nuzzle just medial to the kidney over the renal vessels.1
Adrenal neoplasms can stem from either the adrenal cortex or medulla. In fact, adrenal mass is commonly encountered in clinical practice by both urologists and nephrologists. Approximately 5% of individuals harbor an asymptomatic adrenal lesion: 0.5% in the second and up to 7% in the seventh decade of life.2-4
Although adrenal masses are often discovered incidentally, only appropriate evaluation can establish these neoplasms as insignificant. Indeed, some data suggest that more than 15% of lesions may require resection (Table 1). As such, modern management of so-called adrenal incidentalomas pivots on informed and individualized treatment choices rooted in (1) appropriate risk-assessment for the presence of malignancy and (2) thorough assessment of each mass’s metabolic activity.1
Overview of adrenal neoplasia
The most common adrenal neoplasm is an adenoma—an entirely benign lesion that can be metabolically active, producing excess cortisol or aldosterone in about 7% of cases. Myelolipoma is another benign adrenal tumor. Myelolipomas are oncologically indolent and are metabolically silent, yet they represent fascinating pathologic entities because their histologic structure is identical to that of bone marrow.1
Resection of these lesions, even when large, is rarely necessary. Unlike other adrenal lesions, pheochromocytomas arise from the adrenal medulla and can be malignant in the minority of cases. Malignant extra-adrenal pheochromocytomas, however, are much more common. Ganglioneuromas are exceedingly rare benign lesions that can stem from the adrenal gland and are often heralded by stippled calcifications on imaging.
Meanwhile, cystic adrenal lesions are generally benign, but some authors recommend resection in young and non-comorbid individuals because up to 7% can be associated with malignancy.1 Importantly, unlike oncocytomas encountered in the kidney, malignant behavior is not uncommon (approximately 30%) in adrenal oncocytomas and thus these patients should be managed accordingly. Metastases to the adrenal glands have been described to stem from nearly every organ, but are most common from lung and renal malignancy. In appropriate patients, solitary adrenal metastases are resected.1
Adrenocortical carcinoma is an extremely rare malignancy with only approximately 300 cases diagnosed annually in the United States.5 Recent data reveal that despite increasing “incidental screening” of the adrenal gland with cross-sectional imaging of the chest and abdomen over the past two decades, there has yet to be any improvement in relative survival in patients diagnosed with the disease.5
Nevertheless, because surgical resection offers the only hope of cure, appropriate assessment of primary adrenal malignancy risk is mandatory in patients diagnosed with an adrenal mass.6