갑상선안병증으로오인된비강내횡문근육종의양쪽외안근전이 : 증례보고 신진호 1 이정현 1 임현경 1 이하영 1 박지원 1 백혜진 1 최영준 1 안진희 2 백정환 1 안와에발생하는전이암은주로안와지방이나뼈에발생하며한쪽에국한되어발생하고, 양쪽외안근의미만성비대형태로발생하는경우는매우드물다. 저자들은코에생긴횡문근육종환자에서치료후추적관찰중발생한안와의전이암이양쪽외안근의미만성비대형태로발생하여갑상선안병증으로오인되었던 1예를보고하고갑상선안병증과감별하는데도움을받을수있는소견이무엇인지에대해분석해보고자한다. 서론안와에발생하는전이암은주로안와내지방이나뼈에발생하며외안근에는매우드물게발생한다 (1). 외안근에전이를일으키는경우대부분일측성으로하나의근육에발생하며양측성으로생긴경우는 Medline 검색결과전세계적으로 3예의증례보고가있을뿐이며 (2-4), 이러한경우외안근의이상중가장흔한질환의하나인갑상선안병증과의감별이쉽지않다. 이에저자들은비강에생긴횡문근육종으로치료후추적관찰중이던 49세남자환자에서양측외안근의미만성비대로발현하여갑상선안병증으로오인되었던양측외안근전이암을 1예를보고하고갑상선안병증과의감별에도움을받을수있는소견이무엇인지에대해분석해보고자한다. 증례보고 49세남자환자가일주일전부터발생한안구통증과안구돌출을주소로내원하였다. 과거력에서 2년전왼쪽비강의폐포형횡문근육종으로진단받고 4주기의항암요법 (VAC/IE: Vincristine, Adriamycin, Cyclophosphamide/Ifosfamide- Etoposide) 과왼쪽비강을중심으로총 4860 cgy의외부방사 선조사치료를받았다. 항암및방사선치료후 6개월동안재발소견없이지내던중, 일주일전부터갑자기발생한안구통증과안구돌출이발생하여내원하였다. 안과검사상좌안이우안에비해경미한안구돌출이있으며, 양측에서모든방향의안구운동에제한이있었다. 임상적으로안와가성종양 (inflammatory pseudotumor) 의가능성이높을것으로보았고, 그외림프종, 횡문근육종의국소재발의가능성을고려하여부비동전산화단층촬영및안와자기공명영상을시행하였다. CT와 MRI에서왼쪽상악동및비강의국소재발소견은없었으나우측외직근및좌측상직근을제외한모든외안근들이방추형으로두꺼워져있었다. 양쪽외안근들은 T1과 T2 강조영상에서주변근육과동일한신호강도를보였고, 정상근육과유사한조영증강을보였다 (Fig. 1A - C). 비대되어있는외안근의경계는분명하여주변지방으로의침습소견은없었고건부 (tendinous portion) 는침범되지않았다. 갑상선안병증의가능성을우선고려하여혈청항미세소체항체 (anti-microsomal antibody) 와항갑상샘글로불린항체 (anti-thyroglobulin antibody) 를포함한갑상선기능검사를시행하였으나결과는정상범위였다. 임상및영상소견상갑상선안병증및안와가성종양의가능성을고려하여고용량스테로이드주기요법 (Steroid pulse therapy, methylprednisolone 250 mg) 을시행하였다. 대한자기공명의과학회지 15:176-180(2011) 1 울산대학교의과대학서울아산병원영상의학과영상의학연구소 2 울산대학교의과대학서울아산병원종양내과접수 : 2011 년 8 월 5 일, 수정 : 2011 년 8 월 9 일, 채택 : 2011 년 8 월 23 일통신저자 : 이정현, (138-736) 서울시송파구아산병원길 86, 서울아산병원영상의학과 Tel. (02) 3010-4400 Fax. (02) 476-0090 E-mail: jeonghlee@amc.seoul.kr - 176-
갑상선안병증으로오인된비강내횡문근육종의양쪽외안근전이 a b c d e f Fig. 1. (a-c) Initial orbit MR. Coronal T1-weighted (a), axial T2-weighted (b) and contrast-enhanced axial T1-weighted (c) images show diffuse enlargement and mild enhancement of the extraocular muscles except the left superior and the right lateral rectus muscles with sparing of the tendinous parts. The fat plane is clearly defined between the extraocular muscles and the orbital fat. Note there is abrupt curving and nodularity of the dilated muscle belly at the tendinous portion of the left medial rectus muscle (arrow). (d-f) Follow-up orbit MR 25 days after steroid pulse therapy. In addition to marked enlargement of the extraocular muscles on coronal T1-wieghted image (d), focal nodularity of the involvement muscles are more clearly demonstrated on axial T2-weighted (e) and contrast-enhanced axial T1-weighted (f) images. - 177-
신진호외 g i h Fig. 1. (g-h) 18 F-FDG PET/CT performed on the same day with the 2nd follow-up orbit MRI. An axial 18 F-FDG PET/CT image (g) shows intense hypermetabolism of the thickened bilateral medial and left lateral rectus muscles (SUVmax, 6.0-7.4 g/ml). The coronal maximum intensity projection image (h) shows multifocal hypermetabolic areas involving the axial and appendicular skeleton from disseminated bone metastasis. Contrast-enhanced axial T2-weighted image (i) after additional chemotherapy shows remarkable regression of the metastatic tumor involving the bilateral extraocular muscles. 고용량스테로이드치료이후에도뚜렷한증상호전없이안구통증이동반되기시작하고안구운동제한으로인한복시가악화되어스테로이드치료시작 25일후시행한추적안와자기공명영상에서우측외직근및좌측상직근을제외한외안근의비대가악화되었을뿐만아니라근육의경계가이전과달리뚜렷한다결절성변화를보이고있었다 (Fig. 1D - F). 같은날시행한 18 F-FDG PET/CT에서는체간및사지골격에미만성골전이소견과함께양쪽외안근에미만성 FDG 섭취증가가있었다 (Fig. 1G, H). 자기공명영상과 18 F-FDG PET/CT 소견을고려하여전신골격과양쪽외안근에발생한횡문근육종전이로진단하고항암요법 (vincristine, ifosfamide, dactinomycin) 을추가적으로시행하였다. 항암요법후 2개월째시행한안와자기공명영상에서양쪽외안근의두께는정상범위로감소하였다 (Fig. 1I). 고찰성인에서안와종양중전이성종양은 2.5% 에서 13% 로알려져있다 (5, 6). 일반적인안와내전이는지방조직과뼈에발생하지만, 외안근에발생할경우단일근육의일측성결절성비대 (unilateral nodular enlargement) 로나타나는것으로알려져있다 (1, 7). 외안근의전이와연관된가장흔한원발성종양은유방암, 악성흑색종, 위장관악성종양, 그리고폐암순이다 (1). Lacey 등은 20명환자에서의외안근전이분석결과외안근의침범빈도는내직근 (39%), 외직근 (33%), 상직근 (16%), 하직근 (12%) 의순이었으며대부분은일측성이었고양측성전이는 17% 에서발생한것으로보고하였다 (1). 안와에발생한전이성횡문근육종은매우드물고 (8), 양안의 - 178-
갑상선안병증으로오인된비강내횡문근육종의양쪽외안근전이 외안근을다발성으로침범하여미만성비대의형태로발생한경우는더욱드물어 Medline 검색결과증례보고두예만있을뿐이다 (3, 4). 이러한양측외안근의미만성비대는영상학적소견상다양한질환과혼동될수있으며그중에서대표적인질환이갑상선안병증이다. 갑상선안병증은 CT나 MRI 상에서양쪽외안근특히하직근과내직근의미만성비후의형태로보인다 (9). 근섬유만을특이적으로침범하고힘줄과근막은침범하지않으므로영상에서는주변조직과의경계가명확한것이특징이다 (9). 또한 MRI에서는주변정상근육보다조영증강이증가되고 T2강조영상에서전반적인고신호를보일수있다 (9). 대개의경우갑상선기능검사상의이상을동반하지만드물게기능검사상의이상보다갑상선안병증이먼저발생하는경우도 20% 라고알려져있다 (10). 본증례의경우처음촬영한 MRI 상에서미만성으로비대된외안근의일부에서전체적으로부드러운방추형을보이지않고건부와의경계부위에서결절모양으로갑작스럽게꺾이는소견을보이는것과조영증강이현저히증가되어있지않은점등은흔히보이는갑상선안병증의영상소견과의차이점이라고할수있다. 따라서횡문근육종이나기타악성종양의병력이있는환자에서외안근의미만성비대가있을때앞서언급한것과같은소견들이 MRI에서동반된경우갑상선안병증이외에기저질환의전이에의한소견일가능성을반드시감별하여야할것으로판단된다. 그이외에백혈병과림프종과같은침윤성질환이나안와가성종양등이감별질환에고려될수있으나두질환은외안근을침범했을때근육의건부를흔히침범하고비대칭적인침범양상을보이면서주변지방조직으로의침윤이흔히동반되는점에서본질환과는감별할수있겠다. 결론적으로횡문근육종환자에서양쪽외안근에미만성으로발생한전이암은매우드물어본증례를포함하여세계적으로모두 2예만보고되어있다. 미만성외안근비대의형태로발생하여갑상선안병증과의감별이어려울수있으나영상소견에서비대된외안근이부드러운방추형을보이지않고건부와의경계부위에서결절모양을취하면서갑작스럽게꺾이는모양을 보이거나조영증강이현저히증가되어있지않는경우횡문근육종과같은악성종양의전이를감별질환에포함해야할것으로생각한다. 참고문헌 1.Lacey B, Chang W, Rootman J. Nonthyroid causes of extraocular muscle disease. Surv Ophthalmol 1999;44:187-213 2.Amato MM, Esmaeli B, Shore JW. Orbital rhabdomyosarcoma metastatic to the contralateral orbit: a case report. Ophthalmology 2002;109:753-756 3.Hatton MP, Green L, Boulos PR, Rubin PA. Rhabdomyosarcoma metastases to all extraocular muscles. Ophthal Plast Reconstr Surg 2008;24:336-338 4.Gupta P, Singh U, Singh SK, Kapoor R, Gupta V, Das A. Bilateral symmetrical metastasis to all extraocular muscles from distant rhabdomyosarcoma. Orbit 2010;29:146-148 5.Shields JA, Bakewell B, Augsburger JJ, Flanagan JC. Classification and incidence of space-occupying lesions of the orbit. A survey of 645 biopsies. Arch Ophthalmol 1984;102:1606-1611 6.Lell M, Schulz-Wendtland R, Hafner A, Magener A, Bautz WA, Tomandl BF. Bilateral orbital tumour as the presentation of mammographically occult breast cancer. Neuroradiology 2004;46:682-685 7.Capone A, Slamovits TL. Discrete metastasis of solid tumors to extraocular muscles. Arch Ophthalmol 1990;108:237-243 8.Jones IS, Reese AB, Krout J. Orbital rhabdomyosarcoma: an analysis of sixty-two cases. Trans Am Ophthalmol Soc 1965;63:223-255 9.Mafee MF. Orbit: embryology, anatomy, and pathology. In: Som PM, ed. Head and neck imaging: 4th ed. Mosby, St. Louis. 2003:591-595 10.Burch HB, Wartofsky L. Graves ophthalmopathy: current concepts regarding pathogenesis and management. Endocr Rev 1993;14:747-793 - 179-
신진호외 J. Korean Soc. Magn. Reson. Med. 15:176-180(2011) Bilateral Extraocular Muscle Metastasis of Nasal Rhabdomyosarcoma Mimicking a Thyroid Associated Orbitopathy: A Case Report Jin Ho Shin 1, Jeong Hyun Lee 1, Hyun Kyung Lim 1, Ha Young Lee 1, Jee Won Park 1, Hye Jin Baek 1, Young Jun Choi 1, Jin-Hee Ahn 2, Jung Hwan Baek 1 1 Department of Radiology and Reasearch Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center 2 Department of Oncology, University of Ulsan College of Medicine, Asan Medical Center Metastases to the orbit usually affect the intraorbital fat and bone than the extraocular muscles. Metastasis to the extracoular muscles commonly occurs unilaterally, and diffuse enlargement of the bilateral extraocular muscles due to metastasis is extremely rare. In this report, we will describe a case of diffuse metastasis to the bilateral extraocular muscles from nasal rhabdomyosarcoma masquerading as thyroid associated orbitopathy. We will also discuss about the MR imaging findings helpful for differential diagnosis from thyroid associated orbitopathy. Index words : Rhabdomyosarcoma Alveolar Extraocular muscle metastasis Magnetic resonance imaging (MRI) Thyroid associated orbitopathy Address reprint requests to : Jeong Hyun Lee, M.D., Ph.D., Head & Neck Imaging Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 86 Asanbyeongwon-gil, Songpa-gu, Seoul 138-736, Korea. Tel. 82-2-3010-4400 Fax. 82-2-476-0090 E-mail: jeonghlee@amc.seoul.kr - 180-