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■ Enlargement

As already mentioned, only enlarged adrenal glands can be clearly visualized with ultrasound.

Anechoic Structure

Glands

Enlargement

 

 

Adrenal Cyst

 

 

 

 

 

 

 

 

 

Anechoic Structure

 

 

Intra-adrenal Hemorrhage

 

 

 

 

 

Adrenal

 

Hypoechoic Structure

 

 

Adrenal Abscess

 

Complex Echo Structure

 

 

 

 

 

Cystic Tumor

 

 

 

 

 

 

 

 

 

 

Hyperechoic Structure

 

 

 

 

 

 

 

 

 

Masses adjacent to the adrenal glands. Anechoic adrenal masses require differentiation from anechoic structures that are located near the gland but are not related to it. These include:

●Renal cysts

●Pancreatic pseudocysts

●Splenic vessels

Renal cysts. Parietal cysts located in the upper pole of the kidney are particularly apt to be mistaken for adrenal cysts. They are distinguished by defining the relation of the cyst to the renal parenchyma.

Pancreatic pseudocysts and tumors. Pancreatic pseudocysts often form in the retroperitoneum following acute pancreatitis. The contents of the cysts may be completely anechoic, and the wall is usually irregular (Fig.10.6). Fine-needle aspiration and laboratory analysis demonstrate high levels of pancreatic enzymes. Cystadenocarcinoma of the pancreas can also be a source of confusion (Fig.10.7).

Fig. 10.6 Pancreatic tail pseudocysts are clearly visualized with trans-splenic ultrasound and require differentiation from upper renal cysts and adrenal cysts. Diagnosis is aided by the history and ultrasound-guided fine-needle aspiration.

Splenic vessels. Tortuous and ectatic splenic vessels can mimic a cystic mass in the adrenal region. Shunt vessels in portal hypertension (e. g., secondary to splenic vein thrombosis) can also assume bizarre shapes.

Fig. 10.7 A cystic, septated mass medial to the left kidney is localized to the pancreatic tail, not the left adrenal gland. Imaging and ultrasound-guided fine-needle aspiration identify the lesion as a cystadenocarcinoma of the pancreas.

Adrenal Cyst

A cyst of the adrenal region is anechoic, has smooth margins, and shows distal acoustic enhancement. Its extent is variable. True cysts have regular walls and are filled with serous material (Fig.10.8).

Most cystic masses in the adrenal region are

 

 

secondary cysts that develop following pan-

 

 

creatitis, hemorrhage, or inflammation.

 

 

The greater mobility of adrenal cysts serves

 

 

to differentiate them from hepatic cysts in the

 

 

right adrenal region. Lack of contact with the

 

 

renal parenchyma distinguishes them from a

 

 

cyst of the upper renal pole.

Fig. 10.8

b Behind the right liver lobe is a typical position to detect

 

a Round, sharply circumscribed, echo-free mass located

an adrenal gland cyst with typical cystic criteria: echoic

 

medial to the spleen and cranial to the left kidney: adre-

wall, echo-free content, and dorsal sound amplification

 

nal cyst. Ultrasound-guided fine-needle aspiration ex-

(image courtesy of Dr. Christian Jenssen, Strausberg,

 

cluded pancreatic cyst, hemorrhage, etc.

Germany).

10

Enlargement

369

10

Adrenal Glands

Fig. 10.9 Echo-free intra-adrenal hemorrhage in a newborn.

Adrenal Abscess

An abscess of the adrenal glands is rarely an-

Fig. 10.10 Adrenal abscess. Circumscribed hypoechoic

echoic. It is usually hypoechoic or has a com-

structure in the right adrenal region. Typical inflamma-

plex echo structure. When the contents are

tory laboratory findings. Ultrasound-guided fine-needle

anechoic, the clinical and laboratory findings

aspiration yielded pus.

can differentiate the lesion from an ordinary

 

cyst. The wall is irregular, and distal acoustic

 

enhancement may be present (Fig.10.10).

 

Cystic Tumor

A cystic tumor may be anechoic in rare cases,

Fig. 10.11 Hypoechoic, partly cystic, predominantly solid

but usually it is hypoechoic. The walls are ir-

tumor in the right adrenal gland: adrenal metastasis from

regular in thickness and outline with some

bronchial carcinoma.

 

solid elements (Fig.10.11).

 

Hypoechoic Structure

Adrenal Glands

Enlargement

Anechoic Structure

Hypoechoic Structure

Complex Echo Structure

Hyperechoic Structure

Hyperplasia

Adenoma

Metastasis

Lymphoma

Adrenal Carcinoma

Incidentaloma

Hyperplasia

Hyperplastic adrenal glands are usually hypoechoic, especially in the cortical zone. They appear plump and elongated, may show lowlevel nodular echoes, and usually are only moderately enlarged (Fig.10.12). Adrenal hy-

perplasia can occur, for example, as an adaptive response in ACTH-dependent Cushing syndrome. It may have a paraneoplastic cause, or it may occur in hyperaldosteronism. The hyperplasia is bilateral in most cases. The adrenal

glands are poorly demarcated from their surroundings. Again, CT provides a better view of the hyperplastic adrenal glands, which usually cannot be detected with ultrasound.

370

10

Enlargement

Fig. 10.12

a Hypoechoic enlargement of the adrenal glands, identified as bilateral adrenal hyperplasia.

b The hyperplastic adrenal gland is enlarged to approximately 2.5 cm. Affected glands may retain their normal triangular shape or may be rounded.

c Endosonography detects a small hyperplastic nodule of the region of the proximal crura.

Adenoma

Adenomas are uniformly hypoechoic with

indicate that they are quite common

smooth margins and a round to oval shape,

(10–20%), but most adenomas (90%) produce

although some lesions have scalloped borders

no endocrine symptoms and are too small to be

(Fig.10.13). Adenomas occasionally have a non-

seen with ultrasound. The average size of 23

homogeneous appearance. Autopsy statistics

operated adenomas in one study was 1.5 cm,7

although they may exceed 5 cm in diameter. Adenomas are bilateral in a small percentage of patients. Functioning and nonfunctioning adenomas are indistinguishable by their sonographic features.

Fig. 10.13

a Large, very hypoechoic, sharply circumscribed mass above the right kidney. Typical adrenal adenoma. If the gland is more than 5 cm in diameter, laparoscopic adrenalectomy should be performed.

b Hypoechoic, sharply circumscribed adenoma of the right adrenal gland discovered at routine ultrasound (confirmed by ultrasound-guided fine-needle aspiration).

c Scant vascularity on color Doppler.

Metastasis

With their rich blood supply, the adrenal

margins ( 10.1). The most common primaries

glands are the fourth most frequent site for

are bronchial carcinoma (15–25%) and breast

hematogenous metastasis. Metastases to the

carcinoma. Other possible sources are renal

adrenal glands account for the majority of solid

carcinoma, gastric carcinoma, pancreatic carci-

adrenal tumors. These lesions are less homoge-

noma, and malignant melanoma.8,9 Adrenal

neous than adenomas and often have irregular

metastases are bilateral in up to 30% of cases,

and this can produce the clinical manifestations of Addison disease. Bronchial carcinoma is virtually the only tumor that is associated with isolated adrenal metastases.

Lymphoma

The adrenal region is a rare extranodal site of occurrence for lymphoma. Foci of lymphomatous infiltration have smooth borders and are hypoechoic (Fig.10.14). Differentiation is required from lymphomas in the renal hilum ( 9.2i). If invasion by lymphoma is suspected, other nodal stations should be scanned and commonly infiltrated organs should be closely scrutinized.

Fig. 10.14

a Perisplenic lymphoma in the left adrenal region of a patient with B-cell lymphoma.

b Isolated highly malignant non-Hodgkin lymphoma of the left adrenal gland (rare extranodular dissemination).

371

10

Adrenal Glands

10.1 Adrenal Metastases

Primary tumors that can metastasize to the adrenal glands

●Bronchial carcinoma

●Breast carcinoma

●Renal carcinoma

●Pancreatic carcinoma

●Malignant lymphoma

a Longitudinal scan of an enlarged, hypoechoic adrenal gland with metastatic bronchial carcinoma. The original shape of the gland (triangular or cowl-shaped) is largely preserved (image courtesy of Dr. B. Frentzel-Beyme, Berlin, Germany).

d Irregularly marginated tumor of the right adrenal gland located posterior to the right lobe of the liver: metastatic colon carcinoma.

b Hypoechoic enlarged adrenal gland with infiltration of the diaphragm: metastasis of a bronchial carcinoma. Transverse scan.

e Metastases are generally hypovascular in the color Doppler image, whereas adrenal adenomas may be hypervascular. Metastatic tumor of the right adrenal gland.

c Large hypoechoic, partially irregular metastasis from bronchial carcinoma on the left side (the same patient as in b; bilateral metastasis occurs in 50%).

f Hypoechoic smoothly margined adrenal metastases from bronchial carcinoma.

Adrenal Carcinoma

Adrenal carcinoma is usually hypoechoic with

Fig. 10.15 Adrenal carcinoma may be hypoechoic or may

irregular margins. It frequently infiltrates its

have a complex echo structure. Usually it is relatively

large when diagnosed (in this case 8 cm × 9 cm) and has

surroundings, and metastases can be demon-

irregular margins.

strated in the adrenal region and in other or-

 

gans (e. g., the liver; Fig.10.15).

 

Incidentaloma

An incidentaloma is an adrenal tumor that is detected incidentally in an asymptomatic patient. Incidentalomas are found in 1% of CT examinations.10 They are much less common in ultrasound examinations, if only because of the difficulty in defining small lesions (Fig.10.16). The predominantly hypoechoic tumors listed in Table 10.2 account for the great majority of incidentalomas. Figure 10.17 shows the algorithm used in the investigation of incidentalomas. The recommended endocrine work-up is detailed in Table 10.3. In some cases, ultrasound-guided fine-needle aspiration can also aid in the evaluation of incidentalomas (Fig.10.18).

Hypoechoic tumors of the adrenal region require differentiation from other masses in that region such as a renal tumor (Fig.10.19), accessory spleen (Fig.10.20), lymphoma (Fig.10.21), and gastric folds.

Fig. 10.16

b Hypoechoic tumor detected incidentally in the right

a Approximately 5 cm hypoechoic mass above the right

adrenal region. Because of its irregular margins, biopsy

kidney: typical incidentaloma without associated symp-

was performed. Result: metastasis from a previously un-

toms, detected at routine upper abdominal ultrasound.

diagnosed bronchial carcinoma.

Histology identified the lesion as an adrenal adenoma

 

(most common incidentaloma).

 

372

 

 

 

 

 

 

 

10

Table 10.2 Spectrum and incidence of incidentalomas14

 

 

 

 

Enlargement

Diagnosis

Imaging and

Imaging and

Operation15

 

 

operation13

operation8

 

Mantero 2000

 

 

Reincke 1995

Allolio 2001

 

 

 

 

n

%

n

%

n

%

 

Overall

172

 

267

 

380

 

 

Adrenal adenoma

134

77.9

230

86.1

198

52.1

 

Nonfunctioning adrenal adenoma

119

69.2

206

77.2

137

36.0

 

Adrenal carcinoma

1

0.6

1

0.4

47

12.4

 

Adrenal hyperplasia

–

 

3

1.1

–

 

 

Pheochromocytoma

5

2.9

7

2.6

42

11.0

 

Ganglioneuroma

2

1.2

3

1.1

15

3.9

 

Myelolipoma

6

3.5

9

3.4

30

7.9

Fig. 10.17 Algorithm for investigating an adrenal inciden-

taloma.13

 

 

 

 

 

 

 

Adrenal cyst

5

2.9

6

2.2

20

5.3

 

Metastasis

1

0.6

3

1.1

7

1.8

 

Others

2

1.2

5

1.9

21

5.5

 

Table 10.3 Endocrine laboratory work-up of adrenal incidentaloma13

Initial work-up

Mandatory

● Free catecholamines in 24h urine

 

● Serum cortisol in dexamethasone suppression test (1 mg)

Optional

● Plasma renin activity after 30 min rest period

 

● Potassium excretion in 24h urine

Extended work-up if initial findings are abnormal

Preclinical Cushing syndrome

● High-dose dexamethasone suppression test (8 mg)

 

● CRH stimulation test

Conn syndrome

● Aldosterone-18-glucuronide in 24h urine

●Plasma renin activity and aldosterone at rest and orthostasis

●Selective renal vein catheterization with bilateral blood sampling for aldosterone and cortisol in adrenal venous blood

Fig. 10.18 Algorithm for “sonographic” adrenal tumors and the use of ultrasound-guided fine-needle aspiration.12

Ultrasound-guided Fine-needle Aspiration of an Adrenal Lesion

Given the frequency of incidentally de-

requiring treatment. The sensitivity of adre-

tected adrenal tumors, every case should

nal usFNA is between 90% and 95%, and it

undergo an initial endocrine work-up. If the

can furnish material for cytological or pref-

tumor cannot be positively identified by

erably histological analysis with a relatively

laboratory tests and imaging (ultrasound,

low risk of complications. The procedure is

CT), ultrasound-guided fine-needle aspira-

performed in a lateral position. Access is

tion (usFNA) can supply a diagnosis in cases

more favorable for a right-sided lesion

than a left-sided lesion, and the complication rate is also somewhat higher on the left side. usFNA is particularly indicated for the

oncological investigation of tumors larger than 3 cm (Fig. 10.18).9,11

373

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