Endocrinol Metab 27(3):217-221, September 2012 CASE REPORT 미세침흡인세포검사로진단된외측경부이소성갑상선 이경남 김상미 최진희 류광덕 김보원 신민지 김보현 김인주 부산대학교의학전문대학원내과학교실 A Case of Ectopic Thyroid Tissue Diagnosed by Fine Needle Aspiration in the Lateral Neck Kyung Nam Lee, Sang Mi Kim, Jin Hee Choi, Kwang Duck Ryu, Bo Won Kim, Min Ji Shin, Bo Hyun Kim, In Ju Kim Department of Internal Medicine, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Korea Ectopic thyroid glands generally occur in the midline as a result of abnormal median migration and their presence in lateral to the midline is rare. Embryologically, the thyroid gland is derived from two anlages: a large median endodermal anlage and two lateral anlages. The median anlage produces most of the thyroid parenchyma, whereas the lateral anlage is derived from the fourth pharyngeal pouch and contributes 1-30% of the thyroid weight. In rare cases, failure of the lateral anlage to fuse with the median anlage can result in lateral ectopic thyroid gland. For many years, lateral, aberrant thyroid tissue in adults was a term used almost exclusively for metastatic thyroid carcinoma. However, aberrant, benign ectopic thyroid tissue rarely occurs. We present a 47-year-old man who had incidentally detected mass on the right lateral neck. He was clinically in a euthyroid status and the thyroid function test results were normal as well. Neck ultrasonography revealed a mild diffuse goiter and a 1.22 0.65 cm sized ovoid mass like lesion was located in the right level IV of the neck. The result of fine needle aspiration cytology was adenomatous goiter without lymphoid tissue or any malignancy. We rarely report aberrant, benign ectopic thyroid presence as a lateral neck mass. (Endocrinol Metab 27:217-221, 2012) Key Words: Fine needle aspiration, Neck, Thyroid dysgenesis 서론 갑상선은태생 3주에서 7주사이에설근부의맹공에서경부로이동하여기도앞쪽으로위치하게된다. 갑상선관을따라정상위치로이동하는과정에서이상이발생하면정상위치에서벗어나서갑상선조직이분포할수있고이를이소성갑상선이라고한다. 이소성갑상선은설근부에 (80-90%) 가장흔하게위치하고설하부, 후두전부, 식도, 기관, 심장, 횡격막, 십이지장, 부신, 자궁에서발견되기도한다 [1,2]. 갑상선의발생은 2개의원기로부터이루어지며하나의정중원기와두개의외측원기가있다. 정중원기가정중선에서융합하여갑상선관을따라이동하는과정에서이상이생겨발생하는것이대부분의이소성갑상선의발생학적배경이다. 정중원기에서발생한조직이갑상선의대부분을차지하기때문에경부에발생하는이 Received: 26 August 2011, Accepted: 21 September 2011 Corresponding author: Bo Hyun Kim Division of Endocrinology and Metabolism, Department of Internal Medicine, Pusan National University Hospital, 305 Gudeok-ro, Seo-gu, Busan 602-739, Korea Tel: +82-51-240-7678, Fax: +82-51-254-3217, E-mail: pons71@hanmail.net 소성갑상선은갑상선관이위치했던목의정중선을따라있는경우가많다. 반면갑상선무게의 1-30% 가량은 4번째인두주머니에서기원한외측원기가정중선에서융합하여생성된조직이차지한다. 따라서이과정의발생학적으로이상이생기는경우드물게외측경부에서이소성갑상선이나타나기도한다. 외측경부의이소성갑상선은경부에종물을형성함으로써발견된다. 40세이상의연령군에서성인의외측경부종물은 75% 가악성종양이원인인것으로알려져있다. 기타원인으로인두고랑낭종, 혈관종, 지방종, 감염, 육아종성질환, 쇼그렌병등이있다. 저자들은우연히발견된외측경부종물을주증상으로내원한환자에서양성의이소성갑상선으로진단된증례를경험하였기에문헌고찰과함께보고하는바이다. Copyright 2012 Korean Endocrine Society This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
218 Lee KN, et al. 환자 : 47 세, 남자 주소 : 무통성의경부종물 증례 Anterior UPTAKE (%): 2.0 Fig. 1. Technetium-99m ( 99m Tc) thyroid scan. 99m Tc thyroid scan shows mild diffuse enlargement of the thyroid gland. Lateral neck mass was invisible on thyroid scan. 현병력 : 환자는건강검진으로시행한경부초음파에서우연히발견된무통성의우측경부종대를주소로내원하였다. 최근 6개월동안체중변화는없었다. 약물병력이나방사선조사병력은없었다. 과거력 : 고혈압을 5년전에진단받았다고하나항고혈압약물은복용하고있지않았다. 사회력 : 특이사항없었다. 가족력 : 특이사항없었다. 진찰소견 : 내원시혈압 133/89 mmhg, 맥박 61회 / 분, 호흡수 20 회 / 분, 체온 36 C이었으며의식은명료하고결막창백, 공막황달, 탈수, 경정맥확장, 촉진으로경부임파선종대소견은없었다. 전경부는경미하게전반적인종대소견보였으며압통은없었다. 우측 Level IV 부위에 1.0 cm 크기의종물이만져졌으나압통은없었다. 흉부청진상호흡음은부드러웠고천명음, 나음등은들리지않았으며심청진상박동은규칙적이며잡음또한들리지않았다. 복부진찰상장음은정상이었고복부는부드러웠으며만져지는종물및통증부위는없었다. 사지부종은보이지않았다. A B C D Fig. 2. Ultrasonography of thyroid gland. Ultrasonography of thyroid gland shows a 1.22 0.65 cm sized ovoid mass like lesion in right level IV (white arrow). (A) Transverse view. (B) Longitudinal view. (C) Color Doppler image shows a mass with peripheral vascularity. (D) Follow-up ultrasonography image shows no significant interval change.
Ectopic Thyroid Tissue in the Lateral Neck 219 검사실소견 : 말초혈액검사에서백혈구 5,740/mm 3, 혈색소 13.9 g/ dl, 혈소판 229,000/mm 3, 생화학검사에서아스파르트산아미노전이효소 22 IU/L, 알라닌아미노전이효소 22 IU/L, 락트산탈수소효소 250 IU/L, 총단백 7.9 g/dl, 알부민 4.6 g/dl, 총빌리루빈 0.63 mg/dl, 혈액요소질소 12.2 mg/dl, 혈청크레아티닌 0.9 mg/dl, 칼슘 9.5 mg/ dl이었고나트륨 141.0 mmol/l, 칼륨 3.93 mmol/l, 염소 102.6 mmol/ L이었다. 갑상선호르몬검사 : T3 110 ng/dl (normal range, 80-170), 유리 T4 1.40 ng/dl (normal range, 0.75-2.00), 갑상선자극호르몬 2.01 μiu/ml (normal range, 0.3-5.0) 으로정상갑상선기능을보였고항갑상선글로불린항체 15 U/mL (normal range, 0-60), 항갑상선과산화효소항체 25 IU/mL (normal range, 0-60), 항갑상선자극호르몬항체 0.2 IU/ ml (normal range, 0-1.5) 로모두음성이었다. 갑상선스캔 ( 99m Tc thyroid scan): 경도로종대된갑상선과균일한갑상선섭취가관찰되었다. 갑상선섭취율은 2.0% 로측정되었다 (Fig. 1). 갑상선초음파소견 : 갑상선의무게는 25 g 정도로경미한갑상선종대가있었다. 오른쪽경부 level III에 1.05 cm의경부임파선과왼쪽경부 level III에 0.79 cm 임파선이확인되었다. 각각괴사나석회화가없는저에코의타원형경부임파선이었다. 경부임파선의 fatty hilum이보존되어있어반응성으로커진것으로판단되었다. 오른쪽경부 level IV에서는 1.22 0.65 cm 크기의타원형의경부종물이관찰되었다. 종물은정상적인갑상선과동일한에코강도를보이고역시괴사나석회화는없었고혈관형성도없었다. 감별진단을위해미세침흡인세포검사를시행하였다 (Fig. 2). 병리학소견 : 미세침흡인세포검사에서여포상세포들의군집과소수의대식세포가혼재되어있어선종양갑상선종 (adenomatous goiter) 에합당하였으며, 림프조직이나악성세포는보이지않았다 (Fig. 3). 치료및경과 : 환자는조직학적으로악성의증거가없고증상도없었기때문에매년초음파추적을하면서외래진료를유지하였다. 3년간추적초음파에서경부종물의크기는변함이없었고양쪽에있던경부임파선도경과관찰 2년째크기가감소하였다. 그러나경과관찰 3년째환자는간헐적으로얼굴이붉어지는증상을호소하여종괴효과 (mass effect) 에의해오른쪽내경정맥 (internal jugular vein) 의압박이있을것을우려하여경부전산화단층촬영 (computed tomography, CT) 을시행하였다. CT 결과목빗근 (sternocleidomastoid muscle) 과내경정맥사이에 1.1 cm 크기의타원형종괴가보이지만내경정맥의압박이나혈전은관찰되지않는것으로나타났다 (Fig. 4). 환자는외과적치료에대해거부의사를밝혀증상이계속될때수술적제거를고려하기로하고경과관찰중이다. Fig. 4. Follow-up neck computed tomography after 3 years. The 1.1 cm sized mass was located between right internal jugular vein and sternocleidomastoid muscle (red arrow) without evidence of compression to adjacent structures or thrombosis. 고찰 정상적인갑상선발생과정을거치면갑상선은설근부의맹공에서 A B Fig. 3. Histologic findings of fine needle aspiration of neck mass. (A) The histologic picture of the aspirated specimen shows clusters of follicular cells and colloid (H&E stain, 400). (B) The colloid stains blue or purple with Giemsa staining (Giemsa stain, 400).
220 Lee KN, et al. 2번째에서 4번째기관연골앞쪽까지이동하여위치하게되지만그렇지못한경우이소성갑상선이생기게된다. 이소성갑상선의발생기전은아직불분명하다. 하지만 thyroid transcription factor 1 (TTF- 1), TTF-2 및 PAX-8 의돌연변이가갑상선의발생과이동에관여하는것으로나타나이소성갑상선의병리기전중의하나로추정되고있다 [3,4]. 산발성또는가족성갑상선형성부전이나이소성갑상선에서 PAX-8 의돌연변이가관찰되어, PAX-8 이갑상선과산화효소와갑상선글로불린을관여하는유전자의발달과발현에영향을미치는것으로이해되고있다 [5,6]. 또한목동맥의발생과갑상선의위치도밀접히연관되어있다고보고되었다 [7]. 이소성갑상선의발생빈도는 10만명에서 30만명당 1명정도로추정되지만무증상의이소성갑상선이상당히많을것으로추측되어정확한발생빈도는알기힘들다. 발생위치는설근부에생기는이소성갑상선 (lingual thyroid) 이가장많고설하부, 후두전부등대부분목의정중선에위치하며아주드물게외측경부에서도발생가능하며식도, 기관, 심장, 횡격막, 십이지장, 부신, 자궁에서도드물게발견된다. 한국의이소성갑상선의임상적특징을관찰한한연구에따르면주증상으로무증상종괴가가장많고성장장애, 목이메는느낌, 연하곤란, 한랭불내성과쉰목소리등을호소하는것으로나타났다 [8]. 이소성갑상선은크기가커지면주위조직을압박하여증상을유발하기도한다. 본증례에서는처음에는증상이없었으나추적과정에서얼굴이붉어지는정맥울혈을시사하는증상을호소하였었다. CT에서정맥의압박이증명되지는않았지만환자의이소성갑상선이내경정맥바로옆에있어자세변화등에따라증상이유발되었던것으로판단되며증상이지속되면수술적절제가필요하다고생각된다. 이소성갑상선은정상위치에존재하는갑상선의모든병리조직학적변화를보일수있다. 갑상선기능의항진및저하그리고악성변화등이다양하게나타날수있다 [9-12]. 본증례는정상갑상선기능을보였고경부초음파의도플러영상에서도혈관분포가적어과활동성의조직이아님을확인하였다. 비활동성의조직이므로, 종괴의확진을위하여세침흡인검사를안전하게시행할수있다고판단하였다. 대부분의이소성갑상선은핵스캔촬영으로진단되는경우가많지만이경우는핵스캔은정상이었고, 외측경부종물은전이성악성종양으로진단되는경우가많기때문에조직학적평가는반드시필요하다. 이소성갑상선의악성빈도는, 설갑상선종 (lingual thyroid) 의경우문헌상 1% 가악성으로나타났으나경부외측의이소성갑상선의악성빈도는아직불명확하다 [13]. 하지만과거에는경부외측의이소성갑상선을 aberrant thyroid tumor 라고불리기도했다. 최초로보고된경부외측의이소성갑상선에서악성조직이발견되어붙여진이름이지만이후로악성세포가발견되는증례가다수보고되었었고, 이소성갑상선과악성종양의전이를영상학적검사만으로는구분이어렵기때문에조직세침흡인검사를반드시시행할것을추 천한다. 세침흡인검사전에초음파나동위원소검사를함으로써생 검으로인한기관내출혈및갑상선중독증의합병증을예방할수 있다 [14]. 이소성갑상선의치료원칙은비대해진갑상선이호흡곤란이나 연하곤란등의증상을발생하면이러한증상을없애고, 정상갑상선 기능을유지하는것이다. 갑상선호르몬의투여로갑상선자극호르몬 의분비를억제시켜비대해져있는갑상선을줄일수있다. 수술적 치료는진행성의갑상선저하증, 호르몬요법에도불구하고연하곤 란및상기도폐쇄가발생할경우, 갑상선중독증및악성이의심되 는경우, 미용을목적으로하는경우시행된다 [15-17]. 요약 갑상선은발생과정에서경부전하방으로이동을하여태생 7 주 째전기관에위치한다. 이러한이동과정에서이상이생기는경우 이소성갑상선이나타난다. 이소성갑상선의 80-90% 가정상적인하 강경로인목의중앙부에서발견된다. 그러나드물게경부외측에서 이소성갑상선이발견되기도한다. 경부외측의무통성의종물을주 증상으로내원한 47 세남자환자로정상갑상선기능검사소견을보 이며갑상선초음파에서경부종물로세침흡인검사를시행하여양성 의이소성갑상선으로진단된증례이다. 본증례를통해서, 임상의 들은외측경부종물의감별진단으로이소성갑상선을고려해야하 며이소성갑상선이외측에생겼을때는주위에있는내경정맥을압 박하거나, 정맥내혈전이생길수있으므로환자의증상을잘감시 하고추적초음파를정기적으로실시하여야하겠다. 참고문헌 1. Baik SH, Choi JH, Lee HM: Dual ectopic thyroid. Eur Arch Otorhinolaryngol 259:105-107, 2002 2. Hazarika P, Siddiqui SA, Pujary K, Shah P, Nayak DR, Balakrishnan R: Dual ectopic thyroid: a report of two cases. J Laryngol Otol 112:393-395, 1998 3. Macchia PE, Lapi P, Chiovato L, Busslinger M, Fenzi GF, DiLauro R: Identification of a mutation in the PAX-8 gene in a patient with thyroid ectopy. J Endocrinol Invest 20(Suppl 5):84, 1997 4. Abramowicz MJ, Vassart G, Refetoff S: Probing the cause of thyroid dysgenesis. Thyroid 7:325-326, 1997 5. Macchia PE, Lapi P, Krude H, Pirro MT, Missero C, Chiovato L, Souabni A, Baserga M, Tassi V, Pinchera A, Fenzi G, Gruters A, Busslinger M, Di Lauro R: PAX8 mutations associated with congenital hypothyroidism caused by thyroid dysgenesis. Nat Genet 19:83-86, 1998 6. Congdon T, Nguyen LQ, Nogueira CR, Habiby RL, Medeiros-Neto G, Kopp P: A novel mutation (Q40P) in PAX8 associated with congenital hypothyroidism and thyroid hypoplasia: evidence for phenotypic variability in mother and child. J Clin Endocrinol Metab 86:3962-3967, 2001
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