Imaging findings of biliary hamartomas

Transcription

1 Imaging findings of biliary hamartomas Poster No.: C-2475 Congress: ECR 2012 Type: Educational Exhibit Authors: N. Leo, C. Malaspina; Perugia/IT Keywords: Cysts, Education, Ultrasound, MR, CT, Biliary Tract / Gallbladder DOI: /ecr2012/C-2475 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 14

2 Learning objectives We have retrospectively analyzed the imaging findings of VMCs on ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), MR cholangiopancreatography (MRCP) in four patients, and discuss the different diagnosis with other related diseases. Discerning the imaging characteristics of VMCs is desirable for the differential diagnosis, and thus reducing the needs for invasive methods such as biopsy or laparotomy. Background Biliary hamartomas also called as von Meyenburg complexes (VMCs) are benign liver malformations that histologically contain cystic dilated bile ducts within 15 mm in diameter surrounded by fibrous stroma[1]. They are usually uncovered by autopsy as an incidental finding. Detecting by imaging modalities is thought not to be easy because of their asymptomatic nature and small size[2]. Imaging findings OR Procedure details We shall describe four cases of VMC's, three men and one woman, with ages ranging from 59 to 73 years (mean, 65 years). Hepatic lesions were found incidentally when the patients underwent routine physical checkup by US, CT (n=1), screening for liver metastasis of a known colon adenocarcinoma by US, CT, MRI (n=2), and gallbladder colangiocarcinoma by US, CT, MRI and MRCP (n=1). All imaging studies including US, CT, and MRI were performed in three patients. Histologic confirmation was acquired in two patients. US examinations were performed by using GE LOGIQ E-9 and H-21 Hitachi with convex probes at the frequency of MHz. A helical CT system Philips Brillance 64, 2.5/2.5 mm, KV , ma , ml of iodinated contrast medium 370 mg/ml iv and 30 ml saline solution, 4 ml/sec. MRI was performed by using a GE Orizont LX, 1.5 T, matrix 256x256, SE T1w and T2w 220/4.2 ms (TR/TE) and 1490/92.16 (TR/TE), 8/1 mm; Fast SE MRCP, 2250/540.1 ms (TR/TE), 4000/802.8 (TR/TE), 4-8 mm. Page 2 of 14

3 On US images, we found multiple small scattered hyper-echoic lesions with comet-tail echoes on both the right and left liver lobes with a diameter 2-15 mm (Figure 1). When zoom function was used, some small hypo-echoic lesions were showed to be tiny cystic lesions with distal acoustic enhancement (comet-tail echoes) (Figure 2). The CT images showed multiple hypodense lesions with irregular and round shape (Figure 3). After intravenous administration of contrast medium, all the lesions showed no enhancement, and the delineation of all the lesions became more conspicuous than on plain CT before intravenous administration of contrast medium (Figures 4 and 5 ). MRI was performed in three cases. Multiple small hepatic lesions were demonstrated to be of low signal intensity on T1-weighed images and high signal intensity on T2weighed images (Figures 6 and 7). In one case, MRCP clearly portrayed few tiny irregularshaped and numerous round-shaped small hyper-intense nodules without comunication with intra-hepatic bile ducts (Figure 8). On histology, multiple dilated and tortuous bile ducts lined by a single layer of cubic epithelium surrounded by fibrous stroma not associated with vascular proliferation and contained bile-stained granular or amorphous materials were revealed in two cases, and the diagnosis of VMCs was confirmed. Images for this section: Page 3 of 14

4 Fig. 1: B-mode US showed multiple small hyper- and hypoechoic lesions less than 15 mm in diameter with multiple comet-tail echoes. Page 4 of 14

5 Fig. 2: B-mode US image using zoom function, the tiny hypoechoic lesions and the comet-tail echo were clearly seen. Page 5 of 14

6 Fig. 3: On axial CT in the precontrast phase, multiple small hypodense lesions scattered in the whole liver. Page 6 of 14

7 Fig. 4: On axial CT image in the arterial phase, the small lesions became well delineated when compared on plain CT. No enhancement was noted in these lesions. Page 7 of 14

8 Fig. 5: On axial CT image in the delayed phase, the small lesions didn't showed enhancement. Page 8 of 14

9 Fig. 6: Axial T1 weighed Fat Suppression image revealed small lesions with low signal intensity. Page 9 of 14

10 Fig. 7: Coronal T2 weighed Fat Suppression image revealed multiple small lesions with high signal intensity. Page 10 of 14

11 Fig. 8: Coronal MRCP image revealed multiple small lesions with high signal intensity without comunication with intra-hepatic bile ducts. Page 11 of 14

12 Conclusion VMCs are congenital bile duct malformations due to the failure of embryonic involution[3]. The incidence of VMCs was estimated at % in autopsy series[4]. The most important clinical significance is that VMCs are easily misdiagnosed as multiple liver metastases on imaging[5]. Imaging manifestations of VMCs are various. US findings have been described as hyperchoic, hypoechoic or mixed heterogenic echoic structures[2,5]. These variations might reflect the histologic features of VMCs including dilated bile ducts and fibrocollagenous stroma. Some authors described the sign of multiple comet-tail echoes, and speculated that it might be the specific US finding of VMCs[2]. In our series, multiple small comet-tail echoes appeared in all cases. It manifested as posterior echo enhancement of the lesions, which might be due to the cystic feature of dilated bile duct and therefore resulted in good transmission of the sound beam. This evidence strongly suggests that the sign of multiple small comet-tail echoes is a unique US feature of VMCs, which have diagnostic value. On plain CT images, almost all VMCs that had been reported were demonstrated to be multiple small hypodense lesions. While on enhanced CT images, no enhancement of the lesions was observed in most of the reported cases after intravenous administration of contrast medium[1,2,5], as in our series. This phenomenon might correlate to the poor vascularity of VMCs described on histology[3]. On MRI, VMCs, including our series, were revealed as hypo-intense on T1-weighed images and hyper-intense on T2-weighed images. MRCP has been considered to be highly sensitive in depicting intra- and extrahepatic bile duct anomalies and cystic lesions of the liver as well as their relationship with bile duct system[6]. Although histological confirmation was obtained in only two cases in our series, typical imaging findings and relative long-time imaging follow-up that showed identical findings are strongly suggestive of VMCs. However, the case number in our series is small. Further observations on large series are still needed to clarify our stand. The spectrum of differential diagnosis of VMCs is fairly wide. However, the most important one is liver metastasis especially in patients with extrahepatic malignant tumors. Usually, multiple small metastases are ill defined on plain CT, and show various degrees of enhancement (such as rim enhancement) after intravenous administration of contrast medium. However, for difficult patients, final exclusion of metastatic lesions should still depend on liver biopsy or follow-up imaging studies[7]. As VMCs may coexist with simple hepatic cysts or polycystic liver and kidney diseases, sometimes it is difficult to make a definitive differentiation especially from polycystic liver disease on imaging. We are likely to approve simple hepatic cysts, when the lesions can be larger than 15 mm in diameter and round in shape[1,2,3]. Peribiliary cysts are multiple small cystic dilatations of the Page 12 of 14

13 intrahepatic extramural peribiliary glands and should also be included in the differential diagnoses of VMCs. However, they are located generally in the hepatic hilum and along the larger portal tract[8], which is different from the scattered distribution of VMCs. Micro-abscesses of the liver can be differentiated from VMCs by means of clinical and radiological data, such as fever, epigastralgia, leucocitosis, multiple round or loculated hypodense lesions on CT with peripheric contrast enhancement, and "target" appearance on US[9]. Furthermore, intrahepatic bile duct anomalies such as Caroli's disease can be readily distinguished from VMCs by imaging, especially MRCP that offers optimal visualization of the spatial relationship between hepatic lesions and intrahepatic bile ducts[10]. In conclusion, imaging modalities are useful in the diagnosis and differential diagnosis of VMCs. Imaging findings, such as multiple small comet-tail echoes on US, multiple tiny hypodense lesions scattered throughout the liver with no enhancement on CT, and cystic nature with normal extra- and intrahepatic bile duct on MRI and MRCP, can be considered as typical or highly suggestive manifestations of VMCs. A correct diagnosis might be obtained when typical imaging findings are present even without a histological confirmation, that is necessary only in selected cases. Personal Information References 1 Lev-Toaff AS,Bach AM, Wechsler RJ, Hilpert PL, Gata- lica Z, Rubin R. The radiologic and pathologic spectrum of biliary hamartomas.ajr1995;165: Luo TY, Itai Y,Eguchi N, Kurosaki Y, Onaya H, Ahmadi Y, Niitsu M, Tsunoda HS. Von Meyenburg complexes ofthe liver: imaging findings.j Comput Assist Tomogr1998;22: Cooke JC, Cooke DA. The appearances of multiple biliary hamartomas of the liver (von Meyenberg complexes) on computed tomography. Clin Radiol 1987;38: Redston MS,Wanless IR. The hepatic von Meyenburg complex: prevalence and association with hepatic and renal cysts among 2843 autopsies [corrected]. Mod Pathol1996;9: Page 13 of 14

14 5 Eisenberg D,Hurwitz L, Yu AC. CT and sonography of multiple bile-duct hamartomas simulating malignant liver diseae (case report). AJR 1986;147: Mortele B,Mortele K, Seynaeve P, Vandevelde D, Kun- nen M, Ros PR. Hepatic bile duct hamartomas (von Meyenburg Complexes): MR and MR cholangiography findings. J Comput Assist Tomogr2002;26: Rong-Qin Z, Bo Z, Masatoshi K, Hirokazu O, Tatsuo I. Biliary hamartomas: imaging findings. World J Gastroentorolog 2005;11(40): Nakanuma Y,Sasaki M, Terada T, Harada K. Intrahepatic peribiliary glands of humans. II. Pathological spectrum.j Gastroenterol Hepatol 1994; 9: Callen PW,Filly RA, Marcus FS. Ultrasonography and computed tomography in the evaluation of hepatic microabscesses in the immunosuppressed patient. Radiology1980;136: Brancatelli G, Federle MP, Vilgrain V, Vullierme MP, Marin D, Lagalla R. Fibropolycystic Liver Disease: CT and MR Imaging Findings. RadioGraphics 2005; 25: Page 14 of 14