Adrenal gland tumors

Abdalla Mutwakil Gamal Radiology Department Sebha Medical Center

Contents

• Adrenal gland tumors

• Imaging Adrenal gland tumors

• Cases

ADRENAL GLAND TUMORS

Introduction

• Endocrine Activity

• Benign vs Malignant

• tumors of cortex vs tumors of medulla

Tumors of the Adrenal Cortex

• Hormones of adrenal cortex

• Functional or nonfunctional

Adrenocortical adenoma

• Functional or nonfunctional .

• Epidemiology

• Clinical features – Aldosterone

– Cortisol

– Androgens

– Estrogens

Adrenocortical carcinoma

• Rare

• Majority metastatic

• Functional or nonfunctional

Tumors of the Adrenal Medulla

• Hormones of adrenal medulla

• The most common adrenal medulla tumors

• Extra-adrenal sites

• Neuroblastoma

• Neuroblast cells

• Pediatric age group

• Presentation

• Urine analysis

• Metastasis

• Treatment option

• Pheochromocytoma

• Catecholamines

• 10% malignant

• Solitary or part of a syndrome

• Clinical presentation

• Urine examination

• Treatment

IMAGING ADRENAL TUMORS

• Adrenal masses are seen in 1% of CT-examinations.

• 1.4% to 8.7% of postmortem examinations.

• Mostly benign..

• The most common is adenoma.

• The issue is differentiation.

CT-examination

Adrenal adenomas have two properties that differentiate them from non-adenomas :

1. Low attenuation on unenhanced CT.

2. Rapid wash out of contrast.

Unenhanced CT.

• Threshold value of 10HU

• Sensitivity of 70% and a high specificity of 98% for the diagnosis of an adenoma.

• Lipid rich vs lipid-poor lipoma

ROI at least 1/2 size of mass. Do not include adjacent periadrenal

fat.

Enhanced and Delayed scan.

• Enhanced CT (at 60 sec)

• Delayed scan (at 15 minutes)

• ‘Enhancement wash out' formula

• Attenuation values are measured on unenhanced, initial enhanced (at 60 sec) and delayed CT (at 15 min) .

Absolute enhancement wash out > 60% = adenoma

Relative enhancement wash out > 40% = adenoma

CT-Algorithm benign versus malignant

• Mostly an adrenal mass will be found on an enhanced CT that is performed in patients with abdominal complaints or patients that are referred for lung carcinoma staging.

• As differentiation between benign and malignant is usually not possible on the initial enhanced CT (at 60sec), ordering the patient back for a dedicated adrenal-CT is the best strategy ( although some prefer MRI).

• If on the unenhanced-CT the density is equal to or below 10 HU the lesion is considered to be an adenoma and no further workup is necessary If the density is more than 10 HU the wash out should be calculated. If the washout is not compatible with an adenoma, a biopsy can be performed if a definitive diagnosis is crucial to the patients management.

Algorithm for differentiating adenomas from non-adenomas.

An adrenal mass identified during staging for lung carcinoma.

On an enhanced CT at 60 sec the attenuation value was 22HU.

The next day patient was ordered back for dedicated adrenal CT.

On the unenhanced CT the attenuation value was -19HU indicating the

presence of a lipid-rich adenoma.

No further work up was needed.

Adenoma in patient with lung carcinoma. LEFT: initial enhanced CT (22HU).

RIGHT: unenhanced CT (-19HU).

A dedicated adrenal protocol in a patient with an adrenal mass.

On the unenhanced CT there is a small homogeneous mass that is well

defined. The density is 9 HU, which is characteristic of a lipid-rich

adenoma.

Although the protocol should have stopped at that moment, i.v. contrast

was given to determine the washout.

The enhancement washout = (43 - 22) : (43 - 9) = 62% indicating a fast

washout characteristic of an adenoma.

The lower the density on the unenhanced CT and the faster the washout

the more confident you can be in making the diagnosis of an adenoma..

Dedicated adrenal protocol in a patient with an adrenal mass

The discriminating parameters on CT based on attenuation values only

apply to homogenous lesions.

Metastases may have a relative low HU due to central necrosis.

Adenoma on the right is homogeneously of low density. Metastasis on the left

is inhomogeneous and centrally of low attenuation due to necrosis.

CASES

45-year-old woman with history of breast cancer.

A

B

C

D

• Findings

Axial CECT images (A and B) demonstrate a homogeneous 2.2 x 1.4 cm right adrenal mass that has a density of 28.3 Hounsfield units (HU). Axial NECT images (C and D), obtained at a later date, show the mass has an attenuation of-12.8 HU.

• Differential Diagnosis

Metastasis, Adrenocortical adenoma, Adrenocortical carcinoma, Pheochromocytoma, or Neuroblastoma.

• Diagnosis

Lipid-rich adrenal adenoma.

• Discussion

The evaluation of adrenal masses is critical in the workup of a patient with a known primary malignancy. Adrenal adenomas are common, with an incidence of approximately 8% in autopsy series. The decision to proceed with curative therapy often rests on the characterization of an adrenal mass to exclude distant metastasis. Therefore, a method to noninvasively diagnose adenomas with confidence is needed. Adenomas have a preponderance of lipid-laden cells that usually give them a lower attenuation value than other adrenal masses (e.g., metastasis, pheochromocytoma, adenocarcinoma). Using an attenuation value of less than 10 HU as the cutoff for an adenoma on a NECT, the specificity of diagnosing an adrenal adenoma ranges from 92% to 100%. Using less than 0 HU, the specificity is 100%. Therefore, an adrenal mass with negative attenuation value and no evidence of macroscopic fat is diagnostic for an adrenal adenoma.

2-year-old boy presenting with a palpable abdominal mass.

A

C

D

• Findings Axial CECT image (A) demonstrates a 9.0 x 8.0 cm heterogeneous mass arising in the left upper quadrant. Fat-suppressed sagittal T2-W1 (B), coronal T1-W1 (C), and gadolinium-enhanced, fat-suppressed axial T1-W1 (D) show the solid mass that displaces the left kidney caudally.

• Differential Diagnosis Wilms tumor, Neuroblastoma.

• Diagnosis Neuroblastoma.

• Discussion Neuroblastoma (NB) is the most common solid abdominal mass of infancy arising from the neural crest. The majority of NBs occur in children less than 4 years of age, but they can occur beyond 10 years of age in less than 5% of cases. Most NBs occur in the adrenal gland, but they can be found in other retroperitoneal locations, mediastinum, neck, and pelvis. Patients can present with a palpable mass, hypertension, nystagmus, and abdominal pain. In a child younger than 5 years of age, the two most common solid retroperitoneal masses are Wilms tumor and NB. It is critical to try to determine the organ of origin of these masses. In this case, the mass is separate from the kidney, with no claw sign between the kidney and the mass, suggesting an adrenal origin. Diagnosis can be confirmed by the presence of elevated urinary VMA levels. Wilms tumors, on the other hand, calcify in only 15% of cases, have a renal origin suggested by a claw sign between the renal parenchyma and the mass.

74-year-old woman with incidentally discovered left adrenal mass.

A

B

C

D

• Findings Axial NECT images (A and B) demonstrate a 1.7 x 2.5 cm left adrenal mass with an attenuation value of 16 HU. It has a density of 112 HU on the axial CECT image obtained 60 seconds after injection of intravenous contrast (C). On the 15-minute, delayed CECT image (D), the mass has a density of 46 HU. Also not left-sided renal cysts.

• Differential Diagnosis Metastasis, Adrenocortical adenoma, Adrenocortical carcinoma, Pheochromocytoma, or Neuroblastoma.

• Diagnosis Lipid-poor adenoma.

• Discussion Thirty percent of adenomas have a density of more than 10 HU on NECT. These are termed lipid-poor adenomas. By 60 seconds after injection of intravenous contrast, adenomas enhance to the same degree as nonadenomas. However, on delayed images, the density of adenomas decreases more rapidly than nonadenomas. This has been postulated to be due to altered capillary permeability in nonadenomas. causing prolonged contrast retention. Because of this difference of enhancement, one can perform an “adrenal washout study”‌ to assess adrenal masses that have not yet been characterized. For this, NECT and CECT images (after injection of 150 cc of contrast) obtained at 60 seconds and 15 minutes must be obtained. Region-of- interest cursor needs to be placed on the central portion of the mass, excluding calcifications or small regions of necrosis.

The percentage of enhancement washout can than be calculated using the following formula:

[(E - D)/(E - U)] x 100

Where E is the density value on the 60-second CECT, D is the density value on the 15-minute CECT, and U is the density on the NECT. If the enhancement washout is more than 60%, the lesion can be diagnosed as an adenoma. If it does not meet the 60% threshold, the lesion remains undetermined, and biopsy, in the setting of a known primary tumor, or follow-up imaging are recommended.

In this case, the enhancement washout of the lesion was 69% ([(112 - 46)/(112 - 16)] x‌ 100) and a lipid-poor adenoma was diagnosed.

42-year-old man presenting with abdominal distention.

A

B

C

D

• Findings Axial CECT images demonstrate a heterogeneous, 11-cm, left suprarenal mass containing calcifications. The upper pole of the left kidney is involved by the mass. Note large liver masses and small amount of ascites.

• Differential Diagnosis Metastasis, pheochromocytoma, renal cell carcinoma.

• Diagnosis Adrenocortical carcinoma.

• Discussion Adrenal carcinomas arise from the adrenal cortex where hormones, such as cortisol, aldosterone, androgen, and estrogen, are produced. Most adrenal carcinomas produce hormones (most commonly cortisol), but the hormones produced are often not sufficient to cause symptoms. This accounts for the large size of these lesions before they are clinically symptomatic. The tumors are typically larger than 6 cm and can measure up to 20 cm. Adrenal carcinomas are easily seen on CT. They demonstrate enhancement with contrast, but this enhancement is often heterogeneous due to areas of necrosis. Calcifications may be present in 30% of cases. Adrenal carcinomas can invade adjacent organs, such as the liver, spleen, and kidney, as seen in this case. Vascular invasion can also occur into the adrenal vein, which drains into the IVC.

• The differential diagnosis includes metastases, which are typically smaller, and pheochromocytomas, which are typically clinically symptomatic and thus present when the lesion is much smaller. Because the renal parenchyma is involved, an exophytic primary renal tumor should also be considered in the differential diagnosis. However, the epicenter of the tumor is suprarenal in location, making an adrenal origin more likely. Biopsy of the adrenal gland can easily be performed in most situations to confirm the diagnosis.

References

• Wikipedia, the free encyclopedia [Internet]. Adrenal tumor .[updated 2014 May 24; cited 2014 Sep 25]. Available from : http://en.wikipedia.org/wiki/Adrenal_tumor

• The Radiology Assistant [Internet]. Adrenals: Differentiating benign from malignant. C2005 Sep 26 [updated 2006 May 19; cited 2014 Sep 25]. Available from : www.radiologyassistant.nl/en/p421aee7c659fc/adrenals.html

• Ros PR, Mortele KJ, editors. CT and MRI of the Abdomen and Pelvis: A Teaching File. 2nd ed. Lippincott Williams & Wilkins; 2006.

• The Radiology Blog [Internet]. How To Differentiate Neuroblastoma and Wilms Tumor. C2012 Apr 28 [cited 2014 Sep 25]. Available from : http://www.theradiologyblog.com/2012/04/how-to-differentiate-neuroblastoma-and.html

• Radiopaedia.org [Internet]. Claw sign. C2005 Sep 26 [updated 2006 May 19; cited 2014 Sep 25]. Available from : http://radiopaedia.org/articles/claw-sign-1

• Radiopaedia.org [Internet]. Wilms tumour. C2011 Oct 26 [cited 2014 Sep 25]. Available from : http://radiopaedia.org/images/1439218