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ECR 2013 / C-1829
Adrenal Masses: CT and MR Approach, Spectrum of Imaging Findings and Histologic Correlation
Congress: ECR 2013
Poster No.: C-1829
Type: Educational Exhibit
Keywords: Pathology, Neoplasia, Cancer, Education, Diagnostic procedure, MR, CT, Oncology, Abdomen
Authors: M. Palmeiro1, J. Niza2, N. V. V. B. Marques3, E. M. Abreu4, A. Loureiro2, M. A. E. C. Vasconcelos2, M. Rito2, J. P. Conceição e Silva2; 1Queluz/PT, 2Lisboa/PT, 3Carcavelos/PT, 4Lisbon/PT
DOI:10.1594/ecr2013/C-1829

Imaging findings OR Procedure details

Imaging findings

 

Adrenal Adenoma

 

Adrenal adenomas are the most common adrenal lesions.

Functioning adenomas (Cushing syndrome, Conn syndrome) are uncommon and usually can be confirmed by means of biochemical evaluation in the presence of an adrenal mass.

 

There are no specific morphologic features that permit adenoma characterization, because the majority is small, smooth, and homogeneous when detected.

However, most can be characterized by using lipid-sensitive or washout CT techniques or chemical shift MR techniques.

 

CT findings:

Adenomas are typically well-defined, often homogeneous and may have the same density as normal adrenal tissue.

Most adenomas contain large amounts of intracytoplasmic lipid, therefore many have a low density, often near that of water, on unenhanced examinations (see  Fig. 5).

Intralesional calcifications are rare.

The degree of enhancement of adenomas after intravenous administration of contrast medium does not differ significantly from that of other adrenal tumors, although adenomas show more rapid washout of contrast medium than adrenal metastases.

Rarely, an adenoma can be hemorrhagic, usually in a patient receiving anticoagulant therapy. The presence of hemorrhage results in regions of higher attenuation and heterogeneity.

 

Fig. 5: Left adrenal nonfunctioning adenoma. (a) Axial and (b) coronal unenhanced CT images shows a well-defined left adrenal mass with attenuation of 5 HU. (c) T1-weighted gradient-echo in-phase images, of the same patient, shows adrenal signal intensity (arrow) slightly higher than the spleen (internal reference organ). T1-weighted gradient-echo opposed-phase image (d) shows marked signal intensity loss of the left adrenal lesion with signal intensity markedly lower than of the spleen (*). (e) On histologic examination adrenal cortical adenoma composed of clear cells with abundant intracytoplasmic lipid droplets, forming cords, mimicking the adrenal zona fasciculata.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

MR findings:

The most important characteristic feature of adrenal adenoma is the presence of intracellular lipid. So, MR imaging chemical shift imaging is the most reliable technique for its diagnosis. Most adrenal adenomas demonstrate a loss of signal intensity on out-of-phase images when compared with in-phase images (see  Fig. 5). A decrease in signal intensity of more than 20% is considered diagnostic of an adenoma.

Uniform enhancement on immediate contrast material–enhanced images is also typical of adenomas.

Small, rounded foci of altered signal intensity may be seen within an adenoma due to cystic changes, hemorrhagic component, or variation in vascularity.

                                                                                

 

Simple Cyst

 

Adrenal cysts are uncommon lesions resulting from endothelial proliferation, prior hemorrhage, or parasitic disease.

Adrenal cysts show a 3:1 female predilection.

 

Four types of cysts are recognized on the basis of pathologic classification: endothelial, epithelial, parasitic, and posttraumatic pseudocysts.

 

CT and MR findings:

They usually demonstrate the expected cystic CT and MR imaging features (see  Fig. 6) but some have higher attenuation values at CT. Usually, these lesions have thin (<3-mm-thick) walls and may contain internal septa, both of which can enhance or contain calcifications.

 

Fig. 6: Left adrenal simple cyst. Coronal unenhanced (a) and contrast-enhanced (b) CT scan images shows a left adrenal mass with hydric attenuation (16 HU). Axial T1-weighted gradient-echo in-phase (c), and axial T2-weighted MR images obtained without (d) and with (e) fat suppression images shows an oval, well-circumscribed, left adrenal cyst, with a thin wall. The cyst has a typical appearance, showing low signal intensity at T1-weighted imaging and high signal intensity at T2-weighted imaging.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

 

Myelolipoma

 

Myelolipoma is an uncommon benign tumor composed of mature adipose tissue and hematopoietic tissue.

Myelolipomas do not produce hormones, so most are detected as incidental findings. Occasionally, large tumors or those undergoing tumor necrosis or spontaneous hemorrhage may cause flank pain.

 

These tumors can arise in the adrenal gland or, much less frequently, from an extraadrenal location.

Large myelolipomas can be confused with other retroperitoneal lipomatous tumors such as liposarcoma.

 

CT findings:

CT shows a well-defined mass with variable quantities of fat and soft tissue. The amount of recognizable macroscopic fat varies from almost 100% to none. However, the presence of even the slightest macroscopic fat is very suggestive of a myelolipoma (see  Fig. 7).

Elements of a soft-tissue density are found in varying amounts (see  Fig. 7).

Calcification is seen in up to 20% of the cases.

 

MR findings:

The appearance of a myelolipoma on MR imaging reflects the proportion of fat and of bone marrow elements in the tumor.

The use of fat suppression can help the diagnosis by demonstrating a loss of signal intensity within the fatty component (see  Fig. 7). Fat has a high signal intensity on both T1- and T2-weighted sequences, which is reduced on fat-suppression images.

The bone marrow elements have a low signal intensity on T1-weighted images and moderate signal intensity on T2-weighted images (see  Fig. 7).

 

 

Fig. 7: Left adrenal myelolipoma. Axial (a) and coronal (b) unenhanced CT scans show a left adrenal mass composed of soft tissue, fat and a small calcification (arrow). In another patient, axial T2-weighted MR images obtained without (c) and with (d) fat suppression show a well-circumscribed, heterogeneous, right adrenal mass that as at the right side a small macroscopic fatty component that shows a decrease in signal intensity on the fat-suppressed image (d). The same adrenal mass on axial T1-weighted gradient-echo in-phase MR image (e) show on the left side a crescentic area that on T1-weighted gradient-echo opposed-phase MR image (f) shows loss of signal intensity (*). (g) On histologic imaging, myelolipoma is characterized by a mixture of mature adipose tissue and hematopoietic elements.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

 

Hemangioma

 

Adrenal hemangioma is a rare benign tumor.

Hemangiomas are composed of closely adjacent vascular channels lined with a single layer of endothelium.

These benign tumors do not produce adrenal hormones, and most are large when found as an incidental finding.

 

CT findings:

On CT, hemangiomas are seen as large well-defined masses. They have a soft-tissue density on unenhanced images and exhibit inhomogeneous persistent enhancement on delayed images (see  Fig. 8). Most hemangiomas are calcified, either from phleboliths in the tumor or from previous hemorrhage (see  Fig. 8).

 

MR findings:

The MR findings associated with hemangiomas include a hypointense appearance relative to the liver on T1-weighted sequences. Central hyperintensity may be seen because of hemorrhage. On T2-weighted images, hemangiomas are hyperintense (see  Fig. 8). Peripheral enhancement that persists on delayed images is characteristic.

 

Fig. 8: Left adrenal hemangiomas. Axial precontrast (a), portal venous phase (b) and late venous phase (c) CT scans shows a large, well-defined left adrenal mass, with soft tissue density on unenhanced images, that presents inhomogeneous and globular enhancement over time, with some calcifications. In another patient, axial T2-weighted MR images obtained without (d) and with (e) fat suppression show a well-circumscribed, heterogeneous left adrenal mass, predominantly hyperintense, with a posterior hypointense area. On axial T1-weighted gradient-echo in-phase MR image (f) it appears predominantly hypointense, with a posterior hyperintense area. This lesion corresponded to a left adrenal hemangioma with a posterior area of subacute hemorrhage. (g) On histologic examination, hemangiomas consist on benign neoplasm composed of multiple vascular channels, with blood content, lined by CD34/CD31+ endothelial cells.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

 

Hemorrhage

 

Adrenal hemorrhage can be bilateral or unilateral.

Bilateral adrenal hemorrhage is usually associated with anticoagulation therapy or a blood dyscrasia; less commonly, it is associated with the stress of surgery, sepsis, or hypotension; and rarely, it is caused by trauma.

Unilateral adrenal hemorrhage is usually caused by blunt abdominal trauma and involves the right gland more often than the left. Adrenal vein thrombosis may also cause unilateral adrenal hemorrhage.

 

If spontaneous, an underlying adrenal tumor should be considered, and follow-up imaging or biopsy is required.

 

CT findings:

On CT, acute or subacute adrenal hemorrhage typically has an increased unenhanced attenuation value of 50–90 HU. Follow-up studies show reduction in size of the adrenal mass with a gradual decrease in the attenuation value (see Fig. 9).

The high attenuation value of a recent adrenal hemorrhage is usually readily apparent on unenhanced CT, but is indistinguishable from a solid adrenal neoplasm on contrast-enhanced CT.

Detection of an adrenal mass on contrast-enhanced CT after trauma is usually assumed to result from a hematoma, but an unrelated adrenal neoplasm can be excluded only by unenhanced CT or serial follow-up CT.

 

MR findings:

MR imaging is the most sensitive and specific modality for diagnosing adrenal hemorrhage.

MR imaging features depend on the age of the hemorrhage: in acute phase (less than 7 days after onset) it has hypointensity on T1- and T2-weighted images because of the presence of intracellular deoxyhaemoglobin; in the subacute phase (7 days to 7 weeks after onset) the lesion is hyperintense on T1- and T2-weighted images due to the paramagnetic effect of free methaemoglobin (see  Fig. 9); in the chronic phase, the lesion periphery exhibits low signal intensity on T1- and T2- weighted images, because of the presence of hemosiderin and fibrous capsule or calcifications.

 

Fig. 9: Right subacute adrenal hemorrhage in a preterm newborn that suffered from postpartum stress. Axial T1-weighted gradient-echo in-phase MR image (a) and T1-weighted gradient-echo out-of-phase MR image (b) shows a right adrenal lesion that is hyperintense and as no loss of signal intensity on the out-of-phase MR image(arrows) (b) . On axial (c) and coronal (d) T2-weighted MR images without fat suppression this mass still present a high signal intensity. (d) Right adrenal gland ultrasound done at the same day as the MR study, and (f) at four months later shows reduction of the size of the right adrenal mass (arrows) . (g) On histologic examination, there is a massive intra-adrenal hemorrhage, without any evidence of tumoral cells.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

 

Pheocromocytoma

 

Pheochromocytoma is a rare catecholamine-secreting tumor.

This neoplasm had been called the 10% tumor. This designation is based on the fact that approximately 10% of pheochromocytomas are bilateral, 10% are extraadrenal, 10% occur in children, 10% are detected incidentally and 10% are malignant.

 

The diagnosis of pheochromocytoma results from the detection of an adrenal mass in the appropriate clinical and biochemical setting.

 

Imaging appearances are variable.

Nonfunctioning pheochromocytomas tend to be larger than functioning tumors.

 

CT findings:

Most pheocromocytomas appear as a smooth, round well-defined mass with a density near that of soft tissue. Larger lesions may be heterogeneous because of tissue necrosis or internal hemorrhage (see  Fig. 10). Macroscopic fat can rarely be identified.

These tumors have marked enhancement after intravenous contrast medium administration, reflecting their vascularity, and have washout characteristics typically similar to those of malignant adrenal lesions, regardless of whether the pheochromocytoma is malignant or benign (see  Fig. 10).

Uncommonly these lesions may show washout values consistent with benign disease, low attenuation at unenhanced CT, or poor enhancement after intravenous administration of contrast medium.

 

MR findings:

Up to 70% of pheochromocytomas demonstrate high signal intensity on T2-weighted images (light bulb sign); this finding is probably caused by a cystic component (see  Fig. 11).

However, 30% of lesions demonstrate low signal intensity on T2-weighted images and may be confused with other adrenal disease.

Most lesions show intense enhancement after the administration of contrast material (see  Fig. 10).

Pheochromocytomas do not contain a substantial amount of cytoplasmic lipid, and, therefore, they maintain their signal intensity on out-of-phase GRE chemical shift images (see  Fig. 10).

 

Because manipulation of pheochromocytomas may induce a hypertensive crisis, diagnosis or exclusion of this entity should be achieved as noninvasively as possible.

 

 

Fig. 10: Left adrenal pheocromocytoma. (a) Axial precontrast CT scan shows a large, well delineated, heterogeneous left adrenal mass, with central calcifications and necrotic areas, and peripheral soft tissue density, that displaces the left kidney inferolaterally (*). On axial (b) and coronal (c) enhanced portal venous phase CT scans this lesions shows enhancement of the soft tissue component and peripheral calcifications. On axial T2-weighted MR images (d) this mass as high signal intensity, with central necrotic areas and peripheral solid component. On MR dynamic study images (e) this lesion as early enhancement of the peripheral solid component. On the axial T1-weighted gradient-echo in-phase MR images (f) and out-of-phase MR images (g) this mass shows no loss of signal intensity. (h) On histologic examination, we found a tumor with an alveolar pattern, composed of cells with a granular basophilic cytoplasm, without atypia or mitoses, with areas of hemorrhage and with a prominent eosinophilic stroma.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

Fig. 11: Bilateral adrenal pheocromocytoma. (a) Axial T1-weighted gradient-echo in-phase MR images show bilateral well delineated, heterogeneous hypointense adrenal masses. On axial (b) and coronal (c) T2-weighted MR images these masses have high signal intensity, with hyperintense central necrotic areas and peripheral solid component. (d) On axial T2-weighted MR images obtained with fat suppression they show no macroscopic fat component.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

 

Adrenal Carcinoma

 

Adrenal carcinoma is a rare tumor.

The peak prevalence of this disease occurs in patients 30–70 years of age.

Adrenocortical carcinoma can manifest as a hyperfunctioning mass causing Cushing syndrome or Conn syndrome. Other manifestations include an abdominal mass and abdominal pain.

Most lesions tend to be very large at presentation.

 

CT findings:

The CT appearance of an adrenal carcinoma is that of a heterogeneous and irregular large mass (see  Fig. 12). Central necrosis is common (see  Fig. 12 and 13), and calcifications are  seen in 20–30% of the cases. Enhancement is heterogeneous after intravenous administration of contrast material and CT washout values are consistent with those of other malignant diseases.

Venous extension of tumor is common and can usually be identified on contrast-enhanced images.

 

MR findings:

On MR imaging, carcinomas are usually heterogeneously hyperintense on both T1- and T2-weighted images (see  Fig. 12), reflecting the frequent internal hemorrhage and necrosis.

Hemorrhagic byproducts, principally methaemoglobin, can result in areas of high signal intensity within the lesion on T1-weighted images; areas of necrosis have high signal intensity on T2-weighted images (see Fig. 12 and 13).

Adrenocortical carcinoma can contain foci of intracytoplasmic lipid, which results in a loss of signal intensity on out-of-phase images (see  Fig. 12).

Enhancement is also heterogeneous, revealing nodular areas of intense enhancement and other areas with no enhancement.

Intravenous extension of tumor is also well depicted on MR imaging because data sets can be projected into multiple planes.

 

Fig. 12: Left adrenal carcinoma. Axial precontrast CT scan (a) shows a large, well defined heterogeneous left adrenal mass, predominantly of soft tissue density, presenting central necrotic areas. On axial portal venous phase (b) and late venous phase (c) CT scans this lesion shows early heterogeneous enhancement of the soft tissue component. Axial T2-weighted MR images obtained without (d) and with (e) fat suppression show a well-circumscribed, heterogeneous left adrenal mass, with central necrotic areas, and no macroscopic fat component. On axial T1-weighted gradient-echo in-phase MR images (f) and T1-weighted gradient-echo out-of-phase MR images (g), this lesion shows small foci of loss of signal intensity (arrows) that correspond to small intracellular fatty foci. (h) On histologic examination, this neoplasia presented a diffuse architecture (>33%), high nuclear grade (Fuhrman criteria), less than 25% of tumor is composed of clear cells and with necrosis and vascular, sinusoidal and capsular invasion (these last 4 not seen is this picture). These morphological aspects, along with the location, favor the diagnosis of adrenal cortical carcinoma.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

Fig. 13: Right adrenal carcinoma. Coronal (a) and axial T2-weighted MR images obtained without (b) and with (c) fat suppression show a well-circumscribed, shows an heterogeneous right adrenal mass (arrows), with an abundant central necrotic area, a peripheral solid component, without no macroscopic fat component. Axial T1-weighted gradient-echo in-phase MR image (d) is consistent with the anterior description.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

Large adrenal carcinomas tend to invade the adrenal vein and inferior vena cava.

 

The multiplanar imaging evaluation of disease progression by cephalad extension or invasion of adjacent vascular structures is essential on surgical management.

 

 

Neuroblastoma

 

Neuroblastoma can occasionally be seen in adults, although it usually occurs in childhood, representing the third most common malignant tumor in this age group.

These tumors may be found anywhere along the paravertebral sympathetic plexus.

 

Neuroblastomas that affect adults typically show less calcifications and are more metastatic at the time of diagnosis. Their imaging findings are also hard to differentiate from other malignant diseases, and biopsy is usually required.

 

CT and MR findings:

The imaging findings of neuroblastoma in adults are similar to those in children.

The lack of specificity of imaging features (see  Fig. 14) and more frequent disseminated involvement make lymphoma or metastatic disease likely possibilities in these patients.

 

Fig. 14: Left adrenal gland stage 4 neuroblastoma. (a) Axial precontrast CT scan image show a large, well delineated, heterogeneous left adrenal mass, predominantly of tissue density, with central necrotic areas and some calcifications, it displaces the left kidney inferolaterally (*) and the abdominal aorta to the right and crosses the midline(+) (f) (g). (b) On coronal enhanced portal venous phase CT scan images this lesions shows enhancement of the solid component. (c) On the axial T1-weighted gradient-echo in-phase MR images the same lesion presents predominant low signal intensity, with central areas of more hypointense signal intensity necrotic areas. On axial (d) and coronal (e) T2-weighted MR images this mass as high signal intensity, with more hyperintense necrotic central areas. On MR dynamic study images this lesion as an heterogeneous early enhancement. (h) Typically a small blue cell tumor (minimal cytoplasm, hyperchromatic round nuclei), with poorly defined cytoplasmic borders, here with pronounced pleomorphism due to previous chemotherapy.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

 

Ganglioneuroma

 

Ganglioneuroma is a rare benign tumor composed of Schwann cells and ganglion cells.

Although it can arise in the adrenal medulla, in 20%-30% of the cases, the majority is extraadrenal, located along the paravertebral sympathetic plexus.

These lesions are usually detected incidentally because they do not secrete hormones.

 

CT findings:

On CT, ganglioneuromas appear as a solid adrenal mass ranging from 4 to 22 cm in diameter, without specific imaging features (see  Fig. 15). The density of the lesion on unenhanced images is often less than that of muscle. Contrast-enhanced images show homogeneous or mildly heterogeneous enhancement.

 

MR findings:

On MR imaging, the signal intensity of a ganglioneuroma is less than that of the liver on T1-weighted sequences. Greater heterogeneity is seen on T2-weighted images than on enhanced CT images (see  Fig. 15).

Although the tumor may surround blood vessels, encroachment on their lumen is rare.

 

Fig. 15: Right adrenal gland ganglioneuroblastoma. (a) Axial in-phase T1-weighted MR image shows a heterogeneous mass (arrows) with predominant low signal intensity involving the right adrenal gland. On axial (b) and coronal (c) T2-weighted MR images this mass as heterogeneous high signal intensity. We can also see that this lesion as contra lateral involvement. (d) Axial T2-weighted MR images obtained with fat suppression show no macroscopic fat component in this lesion. On MR dynamic study images this lesion as an heterogeneous moderate enhancement. (e) On histological evaluation, this tumor is composed of numerous collections of abnormal but fully mature ganglion cells.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

 

Metastasis

 

Metastases are the most common malignant lesions involving the adrenal gland. Adrenal metastases are found in up to 27% of patients with malignant epithelial tumors at autopsy.

Common primary sites of tumors that metastasize to the adrenal glands include the lung, breast, melanoma, bowel and pancreas.

Metastases are usually bilateral but may also be unilateral, either small or large.

 

CT and MR findings:

The CT and MR imaging features are nonspecific.

Small metastases are often homogeneous on contrast-enhanced CT, whereas large metastases often have local regions that appear heterogenous as a result of necrosis, hemorrhage, or both (see  Fig. 16 and 17).

Intralesional calcifications are rare.

 

Fig. 16: Right adrenal metastasis of a renal cell carcinoma. Axial precontrast phase (a), axial (b) and coronal (c) arterial phase and late venous phase (d) contrast-enhanced CT scans shows a right adrenal hypervascular mass (arrows). (e) On histological examination, we see a lesion that as mixture of clear and eosinophilic cells in which the immunohistochemical study (vimentin+, CD10+, inibin-) suggesting a renal origin.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

Fig. 17: Right adrenal metastasis of a pulmonary carcinoma. Axial precontrast phase (a), axial arterial phase (b), axial (c) and coronal (d) portal venous phase contrast-enhanced CT scans shows a right adrenal mass with predominant central necrosis and a small peripheral hypervascular component. This patient had also hepatic metastasis (*) and retroperitoneal lymphadenopathy (+). The diagnosis of metastasis of an adenocarcinoma was done, in which the (e) immunohistochemical study (CK7+, TTF1+), along with the past personal history of lung cancer, favored a pulmonary origin.
References: Radiology, Instituto Portugues de Oncologia de Lisboa Francisco Gentil E.P.E. - Queluz/PT

 

On MR imaging, adrenal metastases usually exhibit low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, with progressive enhancement after administration of contrast material.

The most important diagnostic feature is the lack of signal loss on out-of-phase images, in opposite to adenomas.

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