British Journal of Radiology (2005) 78, 170-174
© 2005 British Institute of Radiology
doi: 10.1259/bjr/18362306
Commonly encountered adrenal pseudotumours on CT
T Gokan, MD,
Y Ohgiya, MD,
H Nobusawa, MD and
H Munechika, MD
Department of Radiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan
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Abstract
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There are a variety of causes of adrenal pseudotumours on CT, including gastric diverticulum, prominent splenic lobulation, upper-pole renal mass, pancreatic mass, hepatic mass and periadrenal varices. These adrenal pseudotumours can be elucidated by multiplanar reconstruction using CT and MRI as well as from the axial images.
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Introduction
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Various adrenal pseudotumours have been previously described on CT. The causes of these pseudotumours include duodenum, colon, gastric diverticulum, hepatic tumour, renal mass, pancreatic mass, and periadrenal varices. With meticulous CT technique, it is usually possible to distinguish adrenal pseudotumours from true adrenal tumours. Cases may be elucidated using multiplanar images of CT or MRI. We present CT images of a variety of adrenal pseudotumours with emphasis on the usefulness of three-dimensional (3D) reconstructions of CT and MRI.
The adrenal glands are surrounded by a variety of anatomical structures. Certain anatomical structures and extra-adrenal pathological conditions may produce CT images suggesting adrenal pathology where none actually exists [1–8] (Table 1
). We review and illustrate commonly encountered adrenal pseudotumours.
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Prominent lobation of the hepatic lobe, or hepatic tumour
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Exophitic right hepatic tumour may simulate a right adrenal tumour (Figure 1). The renal fascia is usually fused superiorly and inserts into the diaphragm. However, it may be open superiorly and communicate with the bare area of the liver. Exophitic hepatic tumour adjacent to the bare area may extend into the perirenal space and be confused with a right adrenal tumour (Figure 2) [1].
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Figure 1. Right adrenal pseudotumour in a 60-year-old man with hepatocellular carcinoma. (a) Axial multidetector CT (MDCT) shows a low density (arrow) mass anterior to the upper pole of the right kidney. A small linear structure (arrowheads) suggesting adrenal gland is seen. Left adrenal metastasis (open arrow) is demonstrated. (b) Coronal reformatted MDCT image clearly demonstrates an exophitic hepatic tumour (arrow) and normal right adrenal gland (arrowhead).
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Figure 2. Ruptured hepatocellular carcinoma with extension to the retroperitoneum simulating right adrenal tumour in a 46-year-old man with right upper quadrant pain. (a) Enhanced CT shows tumour in the region of the adrenal gland that simulates an adrenal tumour (arrow). (b) Enhanced CT obtained 2 cm caudal to (a) shows a large perinephric haematoma (arrow). A compressed right adrenal gland (arrowhead) is seen in the medial aspect of the haematoma.
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Gastric diverticulum and redundant gastric fundus
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A fluid-filled gastric fundus, which has not been opacified by orally administered contrast material, may, on occasion, produce a mass-like density in the expected region of the left adrenal gland [3]. A diverticulum of the gastric cardia may simulate a left adrenal mass (Figure 3). A diverticulum of the posterior wall of the gastric cardia may herniate through an area of dorsal mesentery before its fusion with the left posterior body wall. Initially, the diverticulum would lie superior to the pancreas but the inferior aspect of the diverticulum may then lie adjacent to Gerota's fascia and the left adrenal gland. If migration of the diverticulum occurs before renal ascent, the diverticulum could indent Gerota's fascia and interdigitate itself between the left kidney and the left adrenal gland. A diverticulum forming after fusion of the dorsal mesentery might be expected to lie within the lesser sac [4].
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Figure 3. Gastric diverticulum simulating left adrenal tumour in a 43-year-old man with hypertension. (a, b) Axial images of enhanced multidetector CT (MDCT) with oral contrast shows a mass (arrow) of heterogeneous attenuation in the left supra renal region. A linear structure (arrowhead) suggesting left adrenal gland is demonstrated in the lowest cut of the mass. (c) Coronal T1 weighted MR image with positive oral contrast clearly demonstrates diverticulum of the gastric fundus (arrow).
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Fluid-filled colon
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A fluid-filled colon between the kidney and the adrenal gland may simulate an adrenal mass (Figure 4). If the gas is seen in the colon, correct diagnosis is easily made [4]. Intraluminal contrast and thin sections may also be useful.
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Figure 4. Dilated colon simulates left adrenal tumour in a 65-year-old man with rectal carcinoma. (a) Axial multidetector CT (MDCT) shows low density mass (arrow) in a left suprarenal region suggesting adrenal tumour. Of note is low density liver metastases (arrowheads). (b) Axial MDCT obtained caudally to (a) demonstrates that the low density mass is a part of the dilated fluid-filled colon (arrow).
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Splenic lobulation
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Prominent splenic lobulation projecting toward the region of the left adrenal gland may simulate an adrenal mass (Figure 5). The fetal spleen is lobulated, but these lobules normally disappear before birth. Splenic lobulations may persist along the medial part of the spleen [2, 5, 6].
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Figure 5. Left adrenal pseudotumour due to splenic lobulation in a 72-year-old woman with right pleural mesothelioma. (a) Axial CT image suggests a mass of the left adrenal gland (arrow). (b) Axial thin slice (3 mm) images demonstrate the mass is a part of the lobulated spleen (arrow). (c) Oblique coronal volume rendered image of CT clearly demonstrates the lobulated spleen (arrow) close to the left adrenal gland (arrowhead).
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Tortuous or dilated splenic arteries and veins
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Periadrenal and adrenal portosystemic collaterals may be a cause of adrenal pseudotumour, which may not be anatomically distinguishable from the adrenal tumour on CT. Patients with portal hypertension with suspected adrenal tumour may require dynamic CT or MRI to discriminate between left adrenal gland and splenic vessels (Figure 6) [6–8].
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Figure 6. Left adrenal pseudotumour due to dilated portosystemic veins in a 54-year-old man with portal hypertension due to cirrhosis. (a) Axial CT image shows large tubular varix in left suprarenal region. There is a possible left adrenal mass (arrow) that shows slightly less intense enhancement than the surrounding varices. (b) T2 weighted MR image demonstrate "flow void" in the mass (arrow) as well as surrounding varix, indicating flowing blood in the varix.
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Pancreatic tail masses
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Neoplastic, inflammatory, and/or cystic masses arising in the tail of the pancreas may be difficult to differentiate from an adrenal mass [5].
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Exophitic upper pole renal masses
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A mass arising in the upper pole of either kidney may be difficult to differentiate from an adrenal mass [3, 5]. Sagittal or coronal reconstructions may be useful to demonstrate the origin of the mass (Figure 7). The usefulness of thin-section CT has been reported previously [3].
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Figure 7. Pseudotumour of the left adrenal gland due to left upper pole renal cyst in a 56-year-old woman with liver and right adrenal gland metastasis. (a) Axial CT image suggests a cyst (arrow) in the suprarenal area in the posterior aspect of the left adrenal gland (arrowhead). Hepatic metastasis from breast carcinoma invades the right adrenal gland (open arrow). (b) Coronal reformatted CT image demonstrates the cyst of the upper pole of the left kidney with beak sign (arrow).
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Received for publication September 15, 2003.
Revision received May 18, 2004.
Accepted for publication July 18, 2004.
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References
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Abstract
Introduction
