Excerpt from Adrenal Carcinoma

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Background

Adrenocortical carcinoma is a rare malignancy with a poor prognosis. The reported incidence of adrenal carcinoma is 2 cases per million persons. When identified, tumors frequently are large, measuring 4-10 cm in cross-sectional diameter. Adrenal carcinomas arise from the adrenal cortex and are bilateral in up to 10% of patients. Approximately 50-80% are functional tumors, with most causing Cushing syndrome.

Pathophysiology

The adrenal glands reside within the Gerota fascia. The cortex and medulla comprise the 2 functional components of the adrenal gland; anatomically, the gland is composed of a body and lateral and medial limbs.

Frequency

United States

Adrenal carcinoma has an incidence of 1 case in 1,700,000 adults. Adrenal carcinoma accounts for 0.002% of childhood malignancies.

Mortality/Morbidity

Adrenal carcinoma accounts for 0.02% of malignant tumors and 0.2% of cancer deaths.

Race

Adrenocortical carcinoma has no racial predilection.

Sex

Male-to-female ratio is approximately 1:1; however, functional tumors are slightly more common in women, while nonfunctional tumors are slightly more common in men. Male patients with adrenocortical carcinoma often tend to be older than female patients and often have a worse prognosis.

Age

Adrenocortical carcinoma has a bimodal occurrence, with the first peak in the first decade of life and the second peak in the fourth to fifth decades of life.

Although adrenocortical carcinoma is rare in adults, it is even more uncommon in children, comprising only 0.002% of childhood malignancies. In children, adrenal carcinoma is rare and is responsible for only 6% of adrenal tumors, although it is the most common adrenal cortical cancer. In children, 90% of adrenal masses are neuroblastomas (adrenal medulla). Adrenal carcinomas in children are associated with hemihypertrophy and Beckwith-Wiedemann syndrome.

Anatomy

The adrenal gland is composed of the main body, a lateral limb, and a medial limb and often has a characteristic inverted Y, V, or T shape. On CT, the limbs should demonstrate a thickness no greater than that of the adjacent diaphragmatic crus. The right adrenal gland lies anteromedial to the superior pole of the right kidney in a space bordered by the inferior vena cava, liver, and right crus of the diaphragm. The left adrenal gland lies more caudal than the right adrenal gland. It is located anteromedial to the superior pole of the left kidney in a space bordered by the left crus of the diaphragm and splenic vein and is posterior to the pancreas. The adrenal gland is made up of the cortex and the medulla, which are derived from the mesoderm and the neural crest, respectively. The adrenal cortex secrets cortisol, aldosterone, and androgens, while the adrenal medulla secretes epinephrine and norepinephrine.

Arterial supply of the adrenal gland arises from 3 main vessels. The superior adrenal artery originates in the inferior phrenic artery, the middle adrenal artery branches directly off the aorta, and the inferior adrenal artery is a branch of the renal artery.

Venous drainage is simpler, with the adrenal vein entering directly into the vena cava on the right. On the left, the adrenal vein enters into the inferior phrenic vein before exiting into the left renal vein.

Clinical Details

Patients usually present with a large palpable mass, abdominal pain, or Cushing syndrome. Primary adrenocortical carcinomas are large tumors usually measuring more than 5 cm at presentation. Because they are large, the organ of origin often is difficult to determine (Image 1).

Cushing syndrome is the most common clinical presentation in adults with adrenal cortical carcinoma, although Cushing syndrome results from adrenal carcinoma in only 5-10% of patients. Conversely, Cushing syndrome in childhood usually is caused by adrenocortical carcinoma. Clinical presentation depends on whether the tumor is functional. In addition to Cushing syndrome, patients can present with virilization, feminization, precocious puberty, or Conn syndrome, although these manifestations are rare. In children, the most common clinical presentation is virilization, followed by Cushing syndrome.

Functional tumors more often are detected in female patients than in male patients. They often are detected earlier than nonfunctional tumors because of the secretion of hormones.

The following endocrine syndromes are associated with adrenocortical carcinoma:

• Cushing syndrome
• Virilization and precocious puberty
• Feminization
• Primary hyperaldosteronism

Preferred Examination

CT is the study of choice in the evaluation of an abdominal mass or, more precisely, to differentiate a benign adrenal mass from a malignant lesion.

Limitations of Techniques

Although CT is used most widely for evaluating abdominal masses, the origin of the mass often is difficult to discern. In addition, the presence or absence of invasion of adjacent structures is difficult to determine in some patients.

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