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ea European Association of Urology
EUROPEAN UROLOGY
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EU-AČME -
Case Study of the Month
Cortical Adenoma in Adrenohepatic Fusion Tissue: Clue to Making a Correct Diagnosis at Preoperative Computed Tomography Examination
Byung Kwan Parkª,*, Chan Kyo Kimª, Byong Chang Jungb, Yeon-Lim Suhc
a Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
b Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
” Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
Article info
Article history: Accepted May 5, 2009 Published online ahead of print on May 13, 2009
Keywords: Adrenal cortical adenoma Adrenohepatic fusion Computed tomography
EU *ACME www.eu-acme.org/ europeanurology
Abstract
A 45-yr-old woman was admitted to excise a solid hepatic tumor which was incidentally detected at ultrasound examination for an unrelated reason. Preo- perative differential diagnoses included primary or secondary malignant hepatic tumors or adrenal cortical carcinoma due to aggressive imaging features.
The patient underwent adrenalectomy and partial hepatectomy. The tumor proved to be an adrenal cortical adenoma arising from the adrenohepatic fusion tissue and consisted of adenoma cells with lipid-rich cytoplasm. Retrospective review of preoperative computed tomography (CT) images demonstrated that the tumor measured 6 Hounsfield units in mean CT number and was continuous with a medial limb of the right adrenal gland.
C 2009 European Association of Urology. Published by Elsevier B.V. All rights reserved.
* Corresponding author. Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul 135-710, Korea. Tel. +822 3410 6457; Fax: +822 3410 0084. E-mail addresses: rapark@skku.edu, bk1436.park@samsung.com (B.K. Park).
1. Case report
A 45-yr-old woman was admitted for the treatment of known gynecologic diseases, including a uterine leiomyoma and an adnexal cystic mass.
Preoperative ultrasound examination incidentally detected a solid mass in the right lobe of the liver in addition to the gynecologic lesions. Unenhanced and contrast- enhanced computed tomography (CT) scans were performed to preoperatively evaluate the incidental tumor. A solid hepatic mass was detected on these CT images and was
heterogeneously enhanced (Fig. 1). The maximum diameter of the lesion was 3.5 cm. However, we did not exclude the possibility of extrahepatic tumors, including tumor invasion arising from the right adrenal gland or seeding from the ovary cancer. Therefore, we made preoperative diagnoses, includ- ing cholangiocarcinoma, adrenal cortical carcinoma, and ovary cancer implant. Preoperative biochemical laboratory findings, including serum tumor markers, viral hepatitis markers, and adrenal hormones, were within normal ranges.
The patient underwent open adrenalectomy, partial hepatectomy, hysterectomy, and salpingo-oophorectomy.
The incidental adrenal mass was attached to both liver parenchyma and right adrenal gland. No peritoneal carcinomatosis was noted. Frozen section revealed no cancer cells in the incidental mass. The pathologic speci- men revealed adhesion of hepatic parenchyma, right adrenal tissue, and a well-circumscribed yellowish cortical adenoma (Fig. 2). The pathologic diagnosis was confirmed to be an adrenal cortical adenoma arising from the adrenohepatic fusion tissue (Fig. 3). Microscopic examina- tion revealed typical cortical adenoma cells with lipid-rich cytoplasm and close intermingling of adenoma cells and hepatocytes (Fig. 4). Gynecologic lesions were also removed and were confirmed to be a uterine leiomyoma and a hydrosalpinx.
When CT images were retrospectively reviewed, the adrenal tumor was hypodense compared to liver paren-
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chyma, and the mean CT number of the lesion measured 6 Hounsfield units (HU) (range: 2-13 HU) on unenhanced images (Fig. 5). Multiplanar reformation images were created to reevaluate the origin of the adrenal tumor. The medial limb of the right adrenal gland closely abutted the liver and touched the adrenal tumor (Fig. 6), which was well correlated with the pathologic findings (Fig. 2). Indeed, we did not notice these imaging features prior to surgical excision of the tumor.
The patient had a fever at 10 d postoperatively. Post- operatively performed CT images showed a moderate amount of fluid in both hepatectomy site and pleural cavities. Passive lung collapse developed due to the bilateral pleural effusion. However, conservative treatments, includ- ing use of antibiotics and diuretics and postural drainage of sputum, were sufficient for treating the postoperative fever.
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Mean ROI = 6 HU
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2. Discussion
Pathologically, adrenohepatic fusion is defined as fusion of the liver and right adrenal gland with closely intermingling parenchymal cells of these two organs [1]. This event does not occur so rarely but accounts for 9.9% of unselected autopsy cases [1]. It has been suggested that the mechanism of adrenohepatic fusion is that the mesenchymal tissue
defect may cause retardation of capsule formation with parenchymal mixing and failure of local differentiation into fetal and later adult fat cells [2]. However, it has also been suggested that adrenohepatic fusion is an acquired event because it increases in older age [1].
Clinically, adrenohepatic fusion may become a route for cancer extension. Hepatocelluar carcinoma may easily metastasize to the right adrenal gland through the adrenohepatic fusion [3] because there is no capsule between the fused parenchymal tissues. Conversely, adrenohepatic fusion is also a possible route for a malignant adrenal tumor extending to the liver paren- chyma, even though it has not been reported yet. Cancer extension through an adrenoehepatic fusion should be differentiated from hematogenous adrenal metastasis since patients with the former may have a better prognosis than those with the latter following adrenalectomy [3-5].
Radiologically, adrenal adenoma can be easily diag- nosed on unenhanced CT images if the mass measures ≤10 HU on unenhanced CT [6]. This lesion is called lipid-rich adenoma because the cytoplasm has abundant lipid [7]. Chemical shift magnetic resonance imaging (MRI) can diagnose a lipid-rich adenoma more accurately than unenhanced CT [8]. In contrast, a lipid-poor adenoma of >10 HU on unenhanced CT images may be more easily identified on delayed contrast-enhanced CT than chemical shift MRI [9]. Woo et al reported that adrenal cortical adenoma developing from adrenohepatic fusion tissue in an oncologic patient may be mistaken for a metastatic lesion [10]. In their report, however, there was no diagnostic clue to indicate an adrenal cortical adenoma on the preoperative CT images. In a retrospective review of CT imaging features, a diagnosis of adrenal adenoma should have been made easily because it measured ≤10 HU on unenhanced CT images. None of the solid hepatic or adrenal tumors except tumors containing gross fatty tissue are as hypodense as adrenal adenoma on unen- hanced CT images. Additionally, three-dimensional recon- struction of CT images obtained from multi-detector-row CT examination can depict the right adrenal gland touching the mass arising from adrenohepatic fusion tissue [10].
In conclusion, an adrenal adenoma arising from the adrenohepatic fusion tissue might be precisely diag- nosed if the lesion measures ≤10 HU on unenhanced CT and is continuous with a right adrenal gland on multiplanar reformation images. Therefore, these imaging features may help avoid unnecessary surgical procedures.
Conflicts of interest: The authors have nothing to disclose.
EU-ACME question
Please visit www.eu-acme.org/europeanurology to an- swer the following EU-ACME question online (the EU- ACME credits will be attributed automatically).
Question:
What is the most probable diagnosis of an adrenal solid mass measuring <10 Hounsfield units (HU) on unen- hanced computed tomography (CT) images?
A. Metastasis
B. Cortical carcinoma
C. Pheochromocytoma
D. Cortical adenoma
References
[1] Honma K. Adreno-hepatic fusion. An autopsy study. Zentralbl Pathol 1991;137:117-22.
[2] Honore LH, O’Hara KE. Combined adrenorenal fusion and adreno- hepatic adhesion: a case report with review of the literature and discussion of pathogenesis. J Urol 1976;115:323-5.
[3] Okano K, Usuki H, Maeta H. Adrenal metastasis from hepatocellular carcinoma through an adrenohepatic fusion. J Clin Gastroenterol 2004;38:912.
[4] Kim SH, Brennan MF, Russo P, Burt ME, Coit DG. The role of surgery in the treatment of clinically isolated adrenal metastasis. Cancer 1998;82:389-94.
[5] Momoi H, Shimahara Y, Terajima H, et al. Management of adrenal metastasis from hepatocellular carcinoma. Surg Today 2002;32: 1035-41.
[6] Boland GW, Lee MJ, Gazelle GS, Halpern EF, McNicholas MM, Mueller PR. Characterization of adrenal masses using unenhanced CT: an analysis of the CT literature. AJR Am J Roentgenol 1998;171: 201-4.
[7] Korobkin M, Giordano TJ, Brodeur FJ, et al. Adrenal adenomas: relationship between histologic lipid and CT and MR findings. Radiology 1996;200:743-7.
[8] Israel GM, Korobkin M, Wang C, Hecht EN, Krinsky GA. Comparison of unenhanced CT and chemical shift MRI in evaluating lipid-rich adrenal adenomas. AJR Am J Roentgenol 2004;183:215-9.
[9] Park BK, Kim CK, Kim B, Lee JH. Comparison of delayed enhanced CT and chemical shift MR for evaluating hyperattenuating incidental adrenal masses. Radiology 2007;243:760-5.
[10] Woo HS, Lee KH, Park SY, Han HS, Yoon CJ, Kim YH. Adrenal cortical adenoma in adrenohepatic fusion tissue: a mimic of malignant hepatic tumor at CT. AJR Am J Roentgenol 2007;188: W246-8.