조기위암환자에서전이암과감별이필요했던간내단발성괴사성결절 : 3T MRI 및 PET/CT 소견 최우선 1 김기현 1 이화연 1 이종범 1 권귀영 2 간에생기는단발성괴사성결절은매우드문양성질환으로대개아무증상없이우연히발견되고, 간에서생길수있는여러가지단발성병변과의감별을필요로하며, 특히악성종양의병기결정에있어서간내전이암과구별하는것은매우중요하다고알려져있다. 영상의학적으로간의단발성괴사성결절은조영증강이없거나미약한주변부조영증강을보이는경계가좋은간내결절로보고되고있다. 하지만단발성괴사성결절이영상에서과녁모양으로보이는경우는지금까지보고된바없으며, 특히고자장의자기공명영상과양성자방출단층촬영소견이보고된경우도전무하다. 이에저자들은조기위암환자에서과녁모양으로보여전이암과감별이어려웠던간내단발성결절을경험하여이의다양한영상소견을보고하고자하며, 병리학적소견과이에대한문헌고찰을통해원인을알아보고자하였다. 서론간에생기는단발성괴사성결절은매우드문양성질환으로 1983년 Shephred and Lee(1) 에의해처음보고된이래현재까지 60여증례가보고되었다. 이질환의병인은지금까지뚜렷이밝혀진바는없으나외상이나기생충질환과의연관성혹은경화성혈관종의퇴행성변화등여러가지가설들이제기되고있다 (2, 3). 대개아무증상없이우연히발견되고, 간에서생길수있는여러가지단발성병변과의감별을필요로하며, 특히악성종양의병기결정에있어서영상의학적으로간내전이암과구별하는것은매우중요하다 (3, 4). 문헌고찰에따르면지금까지보고된증례의대부분은병리소견에기초한병인추론에대한것이대부분이었으며, 단발성괴사성결절의영상의학적소견에대한보고는아주제한적이어서 10여증례가넘질않고이중자기공명영상 (MRI) 소견이포함된경우는 4예에불과하다 (3-7). 영상의학적소견이보고된증례들중전형적인과녁모양의병변은보고된바없으며, 고자장자기공명영상 (3T MRI) 과양성자방출단층촬영 (PET) 소견이포함된경우도전무하다. 이에저자들은조기위암환자에서발견된과녁모양의간내단발성괴사성결절을경험하여다양한영상소견과함께보고하고자하며, 병리학적소견과연계하여원인을알아보고하고자하였다. 증례보고 77세남자가상복부불쾌감을주소로내원하여시행한위내시경검사에서조기위암이의심되었고조직검사상위암으로확진되었다. 특별한과거력없이지내오던환자로내원당시시행한간기능검사는정상범위였고, B형간염항원과 C형간염항체는음성이었으며, 종양표지자검사 (alphafetoprotein, CEA, CA 19-9) 도정상범위였다. 위암의병기결정을위해시행한다중시기조영증강전산화단층촬영 (Multiphase Computed Tomography, CT) 에서간우엽, 6번분절의피막하부위에약 2.5 cm 크기의단발성결절이우연히발견되었다. 이결절은 CT에서원형의경계가 대한자기공명의과학회지 13:213-217(2009) 1 중앙대학교의과대학부속중앙대학교병원영상의학과 2 중앙대학교의과대학부속중앙대학교병원병리과접수 : 2009 년 10 월 21 일, 수정 : 2009 년 11 월 4 일, 채택 : 2009 년 11 월 13 일통신저자 : 김기현, (156-756) 서울시동작구흑석동 224-1, 중앙대학교의과대학부속중앙대학교병원영상의학과 Tel. (02)6299-2646 Fax. (02) 6263-1557 E-mail: roentgen@cau.ac.kr - 213-
최우선외 명확한형태이었고, 모든시기에서주변정상간실질에비해저음영을나타내었으며의미있는조영증강은보이지않았다 (Fig. 1A). 전형적인전이암의형태를보이고있지않았으나결절의정확한감별을위해초음파 (Ultrasound, US) 와자기공명영상 (Magnetic resonance imaging, MRI) 그리고양성자방출단층촬영 (F-18 FDG PET/CT) 을시행하였다. 초음파에서이결절은주변정상간실질에비해저에코의병변이었으며중심부에고에코의원형부위가관찰되어과녁모양으로보였고 (Fig. 1B), F-18 FDG PET/CT에서는위암은고대사성 (hypermetabolic) 병변으로보였으나이결절은저대사성 (hypometabolic) 병변으로나타났다 (Fig. 1C). MRI에서는 T1, T2 강조영상에서모두저신호강도를보이는결절이었고, 중심부에선 T1 강조영상에서보다낮은저신호강도를보이고, T2 강조영상에서고신호강도를나타내는형태를띠어과녁모양으로관찰되었으며 (Fig. 1D, E), 가돌리늄 (gadolinium) 을이용한조영증강영상에도병변의조영증강은보이지않았다 (Fig. 1F). 다양한영상의학적소견을고려할때전이암의가능성은매우떨어지고양성결절의가능성이높다는판단하에조직학적확진을위해초음파유도하생검을시행하였다. 생검조직의병리학적소견상병변과정상간실질간의경계가분명하며결절의내부는치밀한유리질화된섬유성아교세포로구성되어있고, 병변주변에큰영양혈관이관찰되어단발성괴사성결절로진단되었으며이러한병리학적소견은간내단발성괴사성결절의다양한원인중혈관종의퇴행성변화일가능성이높다고보고되었다 (Fig. 2A, B). 환자는복강경보조원위부위절제술 (laparoscopic assisted distal gastrectomy) 시행받은뒤퇴원하였고, 3개월후추적검사로시행한 CT에서간내결절은의미있는변화를보이지않았다. a b Fig. 1. A 77-year-old male with a solitary necrotic nodule in subcapsular portion of segment VI of liver, showing target appearance. a. Portal venous phase of liver dynamic CT shows 2.5 cm round, well-defined, low-attenuated nodule without significant enhancement (Unenhanced scan is not shown). b. Gray scale US of liver shows a hypoechoic nodule with central s- maller hyperechoic portion. c. F-18 FDG PET/CT shows a hypometabolic nodule in liver, but the gastric cancer shows hypermetabolism (arrow) c - 214-
조기위암환자에서전이암과감별이필요했던간내단발성괴사성결절 d e f Fig. 1. A 77-year-old male with a solitary necrotic nodule in subcapsular portion of segment VI of liver, showing target appearance. d. T2-weighted 3T MRI shows a well-defined, hypointense nodule with smaller central hyperintense area. e. T1-weighted 3T MRI with fat saturation shows a well-defined, hypointense nodule with central more hypointense area. f. 3D GRE dynamic MRI after gadolinium injection shows no significant enhancement. 고찰간에생기는단발성괴사성결절은매우드문양성질환으로그병인은지금까지뚜렷이밝혀진바는없으나외상이나기생충질환과의연관성혹은경화성혈관종의퇴행성변화등여러가지가설들이제기되고있다 (2, 3). 병리학적으로중앙에괴사와주변에탄력섬유 (elastic fiber) 가포함된유리질섬유성피막 (hyalinized fibrotic capsule) 으로구성되어있다 (1). 대개아무증상없이우연히발견되고, 간에서생길수있는여러가지단발성병변과의감별을필요로하며, 특히악성종양의병기결정에있어서영상의학적으로간내전이암과구별하는것은매우중요하다고알려져있다 (3, 4). 하지만단발성괴사성결절의영상의학적소견에대한보고는아주제한적이어서 10 여증례가넘질않고이중자기공명영상 (MRI) 소견이포함된경우는 4 례에불과하여실제임상에서영상의학적소견만으로확진을내리기에는어려움이있다 (3-7). 문헌고찰에따르면결절의크기는대개 3 cm을넘지않으며, 모양은원형이나난원형의경계가명확한결절이었으며드 물게는엽상변연의형태를나타내기도하였다. 주로간우엽, 특히전방피막하부위에호발하며남성에서호발한다고한다 (2, 8). 초음파에서는거의모두저에코의결절이었고, CT 소견은주변정상간실질보다균질한저음영의결절로서내부에출혈이나석회화를시사할만한고음영은없었으며, MR에서는대개 T1 강조영상에서는저신호강도로 T2 강조영상에서는고신호강도로비특이적이었으며, 조영증강초음파나 CT, MR에서모두조영증강은보이지않았다. 본증례에서는 77세남성이며, 2.5 cm 정도크기의경계가명확한원형결절이었으며 CT에서조영증강이되지않는저음영의결절이었다는점들은지금까지보고된증례와비교하여큰차이가없었다. 하지만초음파에서저음영의결절중심부에고에코부분이있었고, MR T2 강조영상에서저신호강도를나타내고중심부에고신호강도를보이는과녁모양의결절이었다는점이지금까지보고와는다른영상의학적소견이었다. 영상의학적으로조영증강이되지않는다는점을고려할때 PET/CT에서저대사성결절의형태를나타내리라추정할수는있겠으나실제로 PET/CT 소견이보고된것은본증례가처음이다. PET/CT에서위암은고대사성병변으로나타났으나간내결절 - 215-
최우선외 a b Fig. 2. Microphotogram of the solitary nectotic nodule of liver. a. High power field microphotogram shows sharp border between normal liver parenchyma and densely hyalinized fibrotic collagenous tissue (Hematoxylin-eosin stain). b. Low power field microphotogram shows a large feeding vessel(asterisk) at the periphery of the nodule (Hematoxylin-eosin stain). 은저대사성병변으로보여전이암의가능성이떨어짐을확인할수있었다. 영상의학적소견을결절의병리학적소견과연관지어보면결절의대부분을구성하고있는치밀한섬유성유리질조직 (densely hyalinized fibrotic collagenous tissue) 에의해 MR T2 강조영상에서저신호강도를나타내었던것으로생각되며, 중심부의고에코성, T1 저신호, T2 고신호강도를보였던부분은괴사부분이었던것으로판단된다. 병리학적소견을통해이질환의원인으로외상이나기생충질환과의연관성혹은경화성혈관종의퇴행성변화등여러가지가설들이제기되고있다 (1-3). Berry와 Sundarensan(9, 10) 등에의하면병리학적으로낭성부분이없으며영양혈관이관찰된다면결절의원인으로혈관종의퇴행성, 경화성변화라고주장하였으며, 본증례도이와유사한병리소견을나타내었으나절제조직이아닌초음파유도하조직생검만으로혈관종의퇴행성, 경화성변화라고보기에는제한점이있다. 또한가지흥미로운사실은간우엽, 전방피막하에결절이위치하는이유는이전의외상에의한변화라고알려져왔다 (2, 8). 감별해야할질환으로는양성질환중에서는해면혈관종, 국소결절과증식, 간세포선종, 단순선천성낭종등이있으며악성질환에서는전이암, 가성종양, 림프종, 재생결절, 이형성결절등이있다 (6, 7). 하지만상기질환들의전형적인영상의학적소견들을숙지하고있고, 지금까지보고된단발성괴사성결절의영상의학적소견들과친숙해진다면비교적유의하게감별할수있으리라생각된다. 결론적으로간내단발성괴사성결절은우연히발견되는드문양성질환으로영상의학적검사에서과녁모양으로도보일수있고, 전이암과감별이쉽지만은않으나다양한영상의학적기법을이용한다면양성병변으로감별이이루어질수있으며경우에따라서불필요한조직검사나간절제등을피할수있을것이라고생각된다. 참고문헌 1.Sheperd NA, Lee G. Solitary necrotic nodule of the liver simulating hepatic metastases. J Clin Pathol 1983;36:1181-1183 2.Zhou YM, Li B, Xu F, et al. Clinical features of solitary necrotic nodule of the liver. Hepatobiliary Pancreat Dis Int 2008;7:485-489 3.Alfieri S, Carriero C, Doglietto GB, Pacelli F, Crucitti F. Solitary necrotic nodule of the liver: diagnosis and treatment. Hepatogastroenterology 1997;44:1210-1211 4.Grazi GL, Mazziotti A, Gruttadauria S, Jovine E, Principe A, Cavallari A. Solitary necrotic nodules of the liver. Am Surgeon 1998;64:764-767 5.Yoon KH, Yun KJ, Lee JM, Kim CG. Solitary necrotic nodules of the liver mimicking hepatic metastasis: report of two cases. Korean J Radiol 2000;1:165-168 6.Iwase K, Higaki J, Yoon HE, et al. Solitary necrotic nodule of the liver. J Hepatobiliary Pancreat Surg 2002;9:120-124 7.Colagrande S, Politi LS, Messerini L, Mascalchi M, Villari N. - 216-
조기위암환자에서전이암과감별이필요했던간내단발성괴사성결절 Solitary necrotic nodule of the liver: imaging and correlation with pathologic features. Abdom Imaging 2003;28:41-44 8.Kondi-Pafiti AI, Grapsa DS, Kairi-Vasilatou ED, Voros DK, Smyrniotis VE. Solitary necrotic nodule of the liver: an enigmatic entity mimicking malignancy. Int J Gastrointest Cancer 2006;37:74-78 9.Berry CL. Solitary necrotic nodule of the liver: a probable pathogenesis. J Clin Pathol 1985;38:1278-1280 10.Sundaresan M, Lyons B, Akosa AB. Solitary necrotic nodule of the liver: aetiology reaffirmed. Gut 1991;32:1378-1380 J. Korean Soc. Magn. Reson. Med. 13:213-217(2009) Solitary Necrotic Nodule of the Liver Mimicking Metastasis in Patient with Early Gastric Cancer : 3T MRI and PET/CT Findings Woo Sun Choi 1, Gihyeon Kim 1, Hwa Yeon Lee 1, Jong Beum Lee 1, Gui Young Kwon 2 1 Department of Radiology, Chung-Ang University Hospital, College of Medicine, Chung-Ang University 2 Department of Pathology, Chung-Ang University Hospital, College of Medicine, Chung-Ang University Solitary necrotic nodule (SNN) of the liver is a very uncommon benign lesion, and it is detected incidentally as a rule. It is important to differentiate SNN radiologically from various single hepatic nodules because SNN mimics hepatic metastasis, especially in staging work up of known primary malignancy. The reported imaging findings of SNN are well-defined nodule without enhancement or with subtle peripheral enhancement. There has been no report about the target-like SNN of the liver and about the imaging finding of 3T magnetic resonance imaging and positron emission tomography. We report a case of targetlike SNN of the liver, mimicking hepatic metastasis, with findings of various imaging modalities and try to find a cause of this nodule according to the pathologic and literature review. Index words : Liver neoplasm MR PET Address reprint requests to : Gihyeon Kim, M.D., Department of Radiology, Chung-Ang University Hospital, College of Medicine, Chung-Ang University, 224-1, Heukseok-dong, Dongjak-gu, Seoul 156-756, Korea. Tel. 82-2-6299-2646 Fax. 82-2-6263-1557 E-mail: roentgen@cau.ac.kr - 217-