(1)
Department of Surgery Division of Surgical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
Introduction
The adrenal glands, although small in size, can be the site of several different types of neoplasms. Primary tumors of the adrenal gland can be either benign or malignant, and the gland is also a common site of metastatic disease from other organs. These neoplasms are the main indication for adrenalectomy.
The adrenal gland is composed of distinct tissue layers, each of which produces a specific hormone. Some tumors of the adrenal gland—known as functional tumors—retain this ability to synthesize hormones, and are characterized by the clinical symptoms caused by this hormone overproduction. An aldosteronoma is a tumor of the adrenal cortex that causes an excess release of the hormone aldosterone. Most patients with this pathology present with poorly controlled high blood pressure despite therapy with multiple antihypertensives. These tumors are typically benign, but resection is indicated for treatment of the hypertension.
Cortisol overproduction, as caused by cortisol-producing adenomas of the adrenal cortex can lead to the development of Cushing’s syndrome. This syndrome can also occur by any upstream cause of increased cortisol production, including adrenocorticotropic hormone (ACTH) producing tumors of the pituitary or other ectopic site. Iatrogenic Cushing’s syndrome can be seen in patients who are prescribed long-term steroid therapy. The hallmarks of this condition are central obesity with purple striae, hirsutism, hypertension, and hyperglycemia. Patients undergoing resection of a cortisol-producing adenoma must be started on a steroid taper postoperatively in order to allow the suppressed contralateral gland to resume normal steroid production.
In addition to the mineralocorticoids and the glucocorticoids discussed above, the adrenal cortex also produces the sex steroids. Androgen and estrogen secreting tumors of the adrenal gland do exist, however these are extremely rare.
Pheochromocytomas are tumors of the adrenal medulla that produce an overabundance of catecholamines (Fig. 20.1). As expected, surges of catecholamine release from these tumors cause symptoms including intense perspiration, palpitations, and tremor. While these symptoms are episodic, many patients also have sustained hypertension—often unresponsive to medical management. Catecholamine release by these tumors may be spontaneous, or can be induced by events such as strenuous physical exertion, trauma, and ingestion of tyramine-rich foods.
Fig. 20.1
Coronal CT scan image of a patient with a right adrenal pheochromocytoma; note the normal adrenal gland on the left
The diagnosis of a pheochromocytoma is made by a combination of imaging appearance and the results of urine and serum tests for catecholamine products. No attempt at biopsy should be made since the procedure can initiate a catecholamine release. Nuclear scintigraphy (i.e., MIBG or PET scan) can be used to detect occult or metastatic lesions in cases where no mass is apparent on imaging but is suggested by biochemical data.
The majority of pheochromocytomas are benign in that they do not have the ability to metastasize, however the clinical symptoms produced can be severe and warrant resection. Importantly, anesthetic induction and manipulation of the tumor are strong stimulants for catecholamine release. Therefore any patient undergoing resection of a pheochromocytoma must undergo alpha and then beta-adrenergic blockage to prevent a hypertensive crisis at surgery.
Given the increased use of imaging tests in medicine, it is not uncommon to discover small adrenal lesions in an asymptomatic patient on imaging obtained for other reasons. These lesions, which have been coined incidentalomas, present a therapeutic challenge for the physician. Nondiscretionary removal of every adrenal lesion would lead to many unnecessary operations since a significant number of these lesions would remain small and clinically insignificant. Exact criteria vary, however adrenalectomy is generally recommended for any tumor found to be hormone producing, or for lesions whose size exceeds 3–5 cm, since increasing size correlates with malignancy.
Adrenocortical carcinoma is a rare, aggressive malignancy of the adrenal gland that can arise de novo, or as a result of malignant transformation of any of the adenomas described above. Patients with functioning tumors may present with the symptoms associated with that hormone. However nonfunctional tumors are typically not discovered until the enlarging size of the mass causes symptoms such as back pain due to local invasion. Unfortunately, most patients already have metastases at the time of diagnosis.
Adrenal metastases can be seen in patients with primary tumors of other organs, including the breast, lung, kidney, liver, and in patients with melanoma and lymphoma (Fig. 20.2). Adrenalectomy is occasionally indicated in select patients with an isolated adrenal metastasis and well-controlled disease.
Fig. 20.2
Coronal MRI image of a patient with a right adrenal metastasis from hepatocellular carcinoma
Surgical Technique
There are multiple surgical approaches for performing an adrenalectomy, including transabdominal and posterior retroperitoneal, both of which may be performed laparoscopic or open. The laparoscopic posterior retroperitoneal approach has several notable advantages and has largely become the standard of care, particularly for small, benign lesions. The open transabdominal approach is more commonly used for larger malignancies, when the tumor is locally invasive, or in situations where vascular control of the vena cava is necessary. Other techniques such as the open retroperitoneal approach may be indicated in select cases. Each version of adrenalectomy must be modified slightly to accommodate the differing venous anatomy of the right and left glands.
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