**2. Epidemiology**

The frequency of adrenocortical tumor diagnosis has increased nowadays due to larger availability of image examination techniques, which makes it a relatively common clinical problem currently. Some studies claim a detection rate of 4% in all abdominal computer tomography [4]. Studies in series of autopsies identified that adrenal masses count less than 1% in individuals younger than 30 years of age and that the rate increases to 7% in those who were 70 or older [1, 2].

Adrenocortical tumors are more common in white, obese, diabetic, and hypertensive individuals. These data might be biased, as elderly, white individuals constitute the groups that most frequently undergo image examinations. It is known that such tumors are rather uncommon in individuals under 50 years of age and are especially uncommon in children [2]. They are more common on the right side [2, 3].

In terms of hormonal production, even though most tumors are nonfunctioning, in up to 15% of cases, there might be a slightly increased production of certain hormones, being cortisol the most common one, which may cause Cushing's syndrome [1].

Around 10–15% of all tumors found are bilateral [2]. Bilateral functioning adrenocortical masses may be congenital adrenal hyperplasia due to a 21-hydroxylase deficiency, adrenal macronodular hyperplasia, or primary hyperaldosteronism [2].

The most common causes of bilateral nonfunctioning adrenal masses are metastases, infections (mycosis, tuberculosis), lymphomas, bleedings, amyloidosis, and, rather rarely, carcinoma and myelolipomas [1].

In a decreasing order of occurrence, the adrenocortical tumor categories are:


**45**

**Figure 1.**

*Preoperative Assessment of Functioning Benign Adrenocortical Tumors: A Clinical Surgical…*

Natural history of adrenocortical tumors is still not completely known [1]. Some studies suggest that most incidentalomas remain within stable size for many years [2]. Long-term follow-up studies suggest that from 5 to 20% of cases involving tumors larger than 1 cm, there is an increase in adrenal mass after an average period of 4 years, regardless of the state of adrenal hormonal production [1]. The typical increase rate of an adrenocortical carcinoma exceeds 2 cm per year, with a survival

Occasionally, tumor reduction might be observed (3–4% of cases). Appearance of mass at the contralateral gland might also be noticed. Nonetheless, the risk of

There is a risk that a nonfunctioning adenoma starts to produce some hormone during follow-up, especially if the mass is larger than 3 cm and mainly in the case of cortisol production. Prospective studies show a 0.3% risk of a subclinical Cushing's syndrome development and a 0.2% chance of it turning into a pheochromocytoma. After a 3- to 4-year follow-up, such risk reaches a plateau that is to say the possibility that it would turn into a functioning one is low. Therefore, repetition of screening for functioning is only prescribed during the first 5 years of follow-up [2]. For the reasons explained here, rather small nodules (smaller than 1 cm) with a benign tomographic aspect need not be further investigated by image, as the

Adrenal adenomas are generally encapsulated, have variable volume and weight, and in most cases have a diameter of 2–4 cm. In nonfunctioning tumors, clear cells of the fasciculate zone, filled with lipids (cholesterol), predominate microscopically, which gives the yellowish coloration. Functioning tumors are usually of varied colors, reddish-brown, with yellowish areas or striae, showing in microscopy the predominance of compact cells, associated with clear cell nests (**Figure 1**). Cortisolproducing adenomas are accompanied by hypotrophy of the adrenal cortex of the affected gland and the contralateral adrenal gland due to adrenocorticotropic hormone (ACTH) (suppression in contrast to aldosterone-producing adenomas in

*Microscopy of an adrenal cortex adenoma showing one or more cell types (A) separated from each other by fibrous septa containing blood vessels (H&E 100×). High increase showing cells in the zona glomerulosa,* 

*fasciculate zone, and reticular zone forming nests and strands (H&E 400×).*

*DOI: http://dx.doi.org/10.5772/intechopen.83514*

expectation lower than 50% within 5 years [1, 2].

malignancy development is low (<1/1000) [1].

**4. Pathological findings**

which this aspect is not observed) [3].

benignity chance is high, whereas the risk of growth is low [2].

**3. Natural history**


*Preoperative Assessment of Functioning Benign Adrenocortical Tumors: A Clinical Surgical… DOI: http://dx.doi.org/10.5772/intechopen.83514*
