PMC2799643_01
Adrenal cortical adenoma arising from ectopic adrenal gland in liver.. A. Transverse US image shows 2.5 cm subtle hypoechoic nodule (arrows) in segment VII of liver.. B. On unenhanced CT image (left upper), lesion (arrow) shows marked low attenuation and its CT attenuation number was -4 HU, suggesting presence of fat within lesion. After contrast administration, lesion (arrow) showed heterogeneous enhancement on arterial (right upper) and portal (left lower) phase images, as well as clear washout on delayed (right lower) phase images. CT attenuation numbers were 29, 82, and 30 on three dynamic phases, respectively.. C. On in- (left) and opposed (right) phase T1-weighted gradient recalled echo MR images, marked signal drop of lesion (arrow) as well as in liver is demonstrated, which suggests abundant fatty component within lesion and background liver, respectively.. D. After Gd-EOB-DTPA administration, lesion (arrow) shows modest enhancement on arterial phase (right upper) compared to unenhanced image (left upper) and washout pattern on portal (left lower) and 3-minute equilibrium (right lower) phase images.. E. Coronal MR images obtained 15 minutes after contrast injection clearly depict relationship between lesion (*) and right adrenal gland (arrowheads). Thin hyperintense capsule is clearly seen between two (in right image).. F. Hepatobiliary phase image obtained 20 minutes after contrast injection demonstrates clear defect of lesion (arrow) compared to hyperintense background liver. However, subtle hyperintense focus (arrowhead) is seen off-center of lesion, indicating possibility of contrast uptake by tumor. Also note thin hyperintense rim (thin arrows) by hepatocytes at medial aspect of lesion, suggesting intrahepatic location of lesion.. G. Gross pathologic specimen reveals 2.9 x 2.8 x 2.5 cm yellowish nodule surrounded by normal liver parenchyma and liver capsule (arrows). Note small foci of hemorrhage (arrowhead) off-center of lesion corresponding to area showing focal hyperintensity on 20-minute delayed MR images.. H. Microscopic photograph (original magnification x200, Hematoxylin & Eosin staining) shows well encapsulated nodule (A) surrounded by hepatocytes (H) and separated from adjacent perihepatic tissue (T) by fibrotic capsule (*) and hepatocytes.. I. On low-power field microscopic photograph (original magnification x40, Hematoxylin & Eosin staining), adrenal adenoma exhibits clear, lipid-laden cells arranged in sheets or nests (A) and contains organizing hematoma (arrows) in dilated vessel with inner vascular proliferation (*) corresponding to focal contrast uptake area on 20-minute delayed MR images.
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In addition, an approximately 2.7 cm low-echoic lesion was found in segment VII of the liver (Fig. 1A). On a precontrast scan, a 2.5 cm well-demarcated, low-attenuating nodule was seen in the subcapsular area of hepatic segment VII (Fig. 1B). After contrast administration, the lesion showed heterogeneous enhancement on arterial and portal phase images and washout on delayed phase images (mean HU: -5 on precontrast phase, 27 on arterial, 89 on portal, and 46 on delayed phase) (Fig. 1B). On in- and opposed-phase T1-weighted gradient recalled echo images, a marked signal drop of the lesion, as well as of the liver was noted, suggestive of an abundant fatty component within the lesion and the background liver (Fig. 1C). After Gd-EOB-DTPA administration, the lesion showed modest arterial enhancement on the arterial phase, and a washout pattern on the portal and equilibrium (3 minutes) phase images (Fig. 1D). A coronal multi-planar reformatted image obtained 15 minutes after contrast injection clearly depicts a relationship between the lesion and the right adrenal gland (Fig. 1E). Even though the hyperintense focus seen on hepatobiliary phase may occur due to the nonspecific retention of gadolinium, it also may indicate the possibility of hepatocyte-specific contrast uptake by the tumor (Fig. 1F). The gross specimen showed a 2.9 cm yellowish nodule within the liver (Fig. 1G). A microscopic examination showed that the nodule was well encapsulated and completely surrounded by hepatocytes, hence confirming its intrahepatic location (Fig. 1H). The tumor was confirmed as an adrenal cortical adenoma consisting of clear cells with abundant cytoplasm (Fig. 1H). A retrospective microscopic examination demonstrated that dilated vessels and an inner organizing hematoma with vascular proliferation off-center of the lesion corresponded to the area showing focal contrast uptake at 20 minute delayed MR images (Fig. 1I).