C A S E REPORT pissn: 2384-3799 eissn: 2466-1899 Int J Thyroidol 2016 November 9(2): 180-184 https://doi.org/10.11106/ijt.2016.9.2.180 분화갑상선암에대한방사성요오드잔여갑상선제거후전신스캔에서우연히발견된난소의성숙기형종과요관암 울산대학교의과대학서울아산병원내과학교실 1, 병리학교실 2 오혜선 1, 송의연 1, 송동은 2, 김원배 1 Incidental Detection of Struma Ovarii on the Whole Body Scan in a Differentiated Thyroid Cancer Patient Hye-Seon Oh 1, Eyun Song 1, Dong Eun Song 2 and Won Bae Kim 1 Departments of Internal Medicine 1 and Pathology 2, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea Post-therapeutic whole body scan (RxWBS) after radioactive iodine (RAI) remnant ablation (RRA) is useful for detect recurrent or metastatic foci of differentiated thyroid carcinoma (DTC) after total thyroidectomy. However, there is rare possibility of false positive iodine uptake in WBS. Here, we report a case of a 72-year-old woman, who underwent RRA after total thyroidectomy due to follicular variant papillary thyroid carcinoma. There is an abnormal iodine uptake in RxWBS in pelvic cavity. Additional single photon emission computed tomography (SPECT)-computed tomography (CT) imaging showed an intensive I-131 avid mass in left ovary. There was a multiple calcified mass in left ovary and enhancing wall thickening in left ureter with hydronephrosis in contrast enhanced CT. She underwent hysterectomy, oophorectomy, left ureterectomy and nephrectomy and diagnosed as mature cystic teratoma with thyroid tissues and ureter cancer. Struma ovarii should be considered if there was abnormal RAI uptake in pelvic cavity. I-131 SPECT-CT is useful for differential diagnosis of abnormal iodine uptakes in WBS. Key Words: Differentiated thyroid cancer, Iodine uptake, Teratoma, Struma ovarii 서론 분화갑상선암의치료에는수술과추가적인방사성요오드잔여갑상선제거술그리고갑상선호르몬제복용을통한갑상선자극호르몬 (thyroid stimulating hormone; TSH) 억제가있다. 분화갑상선암에대한수술적치료후환자의재발위험도를분석하고그에따라방사성요오드치료여부및용량을결정하도록권고하고있다. 1,2) 방사성요오드잔여갑상선제거술은갑상선글로 불린 (thyroglobulin; Tg) 을분화갑상선암의종양표지자로활용할수있도록도와주며, 수술로제거하지못한미세잔존암을치료하여재발을예방하는효과를기대할수있다. 3) 방사성요오드치료후전신스캔은분화갑상선암의재발또는전이를평가할수있는유용한검사방법이지만, 갑상선이외의다른장기에서도위양성요오드섭취가가능하다는보고들이있다. 4,5) 위양성병변은분화갑상선암의전이와감별이필요하고이는향후환자의치료방침을결정하는데매우중요한요소로작 Received April 19, 2016 / Revised June 14, 2016 / Accepted June 20, 2016 Correspondence: Won Bae Kim, MD, PhD, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea Tel: 82-2-3010-3913, Fax: 82-2-3010-6962, E-mail: kimwb@amc.seoul.kr Copyright c 2016, the Korean Thyroid Association. All rights reserved. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 180
Incidental Detection of Struma Ovarii on the Whole Body Scan in a Differentiated Thyroid Cancer Patient 용한다. 갑상선조직을포함하는난소종양은전신스캔에서위양성요오드섭취를보일수있다. 저자들은갑상선전절제술후소포변이유두암이진단된 72세여자환자에서방사성요오드잔여갑상선제거술을시행하였고, 전신스캔에서복강내에강한요오드섭취를보이는병변을확인하였다. 추가적인검사를통해이병변은난소의성숙기형종으로확인되었고, 동반된요관암이확인되어이에대해증례보고와함께관련된여러문헌을고찰하고자한다. 증례 70세여자환자가목에촉지되는혹을주소로내원하였다. 과거력상특이병력은없었으며신체검진에서갑상선우엽에약 3 cm 크기의부드럽고단단하며유동적인종물이촉지되었고, 경부에다른만져지는림프절은없었다. 갑상선기능검사결과는혈중갑상선자극호르몬 (TSH) 이 0.27 miu/l (0.4-5.0), 유리 T4는 16.7 pmol/l (10.3-24.5), 총 T3는 2.427 nmol/l (1.505-2.765) 로확인되었다. 경부초음파검사에서우엽하부에 5.5 cm 크기의저에코성경계가명확한석회화를동반하지않은결절과좌엽중앙부에 0.7 cm 크기의등에코성경계가불명확한거대석회화를동반한악성이의심되는결절이확인되었다 (Fig. 1A, B). 두개의결절에대해서초음파유도하중심부조직검사를시행하였다. 조직검사결과, 우엽의결절은여포성종양 (follicular neoplasm, Fig. 1C), 좌엽의결절은양성소견을보였다. 우엽의결절에대해서는 NRAS codon 61번에대한유전자검사를시행하였으며, NRAS Q61R (CAA CGA) 유전자돌연변이가확인되었다. 여포성종양이의심되고, NRAS 유전자돌연변이가확인된갑상선결절에대해서진단적수술을하기로하였으며, 갑상선전절제술을시행하였다. 수술후병리검사에서육안적으로 5.5 4.2 3.7 cm 크기의경계가명확한노란색딱딱한결절이우엽에서확인되었고, 좌엽에는 0.8 0.6 0.6 cm 크기의경계가불명확한짙은노란색결절이확인되었다 (Fig. 1D). 현미경적검사에서우엽의결절은피막형비침윤성의소포변이유두암 (follicular variant papillary thyroid carcinoma) 의소견을보였으며, 좌엽의결절은피막형침윤성의소포 Fig. 1. Representative radiologic and pathologic images of the thyroid cancer. Thyroid ultrasonograhy (US) images (A, B) thyroid US reveals 5.5-cm-sized hypoechoic nodule with smooth margin at the lower pole of right thyroid lobe (A) and another isoechoic 0.7-cm-sized nodule with irregular margin at the mid pole of left thyroid lobe (B). (C) Core needle biopsy for the right thyroid nodule revealed histological features of suspicious for follicular neoplasm with thin tumor capsule and microfollicular proliferation (H&E staining, magnification x200). (D) Large well-demarcated ovoid mass (5.5x4.2x3.7 cm) on lower pole of right lobe and several ovoid nodules were in surgical specimen after total thyroidectomy showed. (E) Tumor on right lobe revealed encapsulated invasive follicular variant of papillary carcinoma (FV-PTC) with capsular invasion (H&E staining, magnification x200). (F) Tumor cells of encapsulate invasive FV-PTC revealed mild nuclear atypia including enlarged nuclei, pale chromatin, irregular nuclear membrane and oval nuclear shape, supporting the diagnosis of FV-PTC (H&E staining, magnification x400). 181 Int J Thyroidol
Hye-Seon Oh, et al Fig. 2. Representative radiologic and pathologic images of the mature cystic teratoma. (A) Posttherapeutic whole body scan at 7 days after the administration 2.96 GBq I-131 showed multifocal thyroid bed uptake due to remnants of normal thyroid and intensive uptake on pelvic area. (B) Additional single photon emission computed tomography (SPECT)-computed tomography (CT) image at 21 days after I-131 remnant ablation showed 8.5-cm-sized intensive radioiodine-avid mass in left ovary or uterine fundus. (C) Abdominopelvic CT showed multiple calcified mass (hollow arrow) with contrast enhancement in left ovary and enhancing wall thickening in left distal ureter (read arrow) with hydronephrosis (arrowhead). (D) Mature cystic teratoma was found on left ovary with struma ovarii component composed of hyperplastic thyroid follicles (H&E staining, magnification x40). (E) Focal adenomatous hyperplasia was identified in the areas of struma ovarii (H&E staining, magnification x200). 변이유두암으로확인되었다 (Fig. 1E, F). 종양은모두갑상선실질내에국한되어서병기는 pt3nxmx였다. 수술 6주후 2.96 GBq의 I-131 방사성동위원소잔여갑상선제거술을시행하였다. 갑상선호르몬을중단하여방사성요오드치료를시행하였으며, 치료당시검사에서혈중 TSH는 35.8 miu/l, 유리 T4는 4.2 pmol/l 이었고, 갑상선글로불린과항갑상선글로불린항체는각각 3720 μg/l (1-23.3) 과 108 kiu/l (0-60) 로확인되었다. 치료이후 2일째, 7일째시행한전신 I-131스캔에서전경부에다발성잔여갑상선조직과복부에 I-131 의강한섭취증가소견이확인되었다 (Fig. 2A). 추가적 인 single photon emission computed tomography (SPECT)-computed tomography (CT) 검사에서좌측난소또는자궁저부에해당되는곳에장경 8.5 cm 정도의경계가명확한다발성석회화를동반한결절에서 I-131의섭취가증가되어있음을확인할수있었다 (Fig. 2B). 복부및골반 CT상에서는다발성석회화를동반한복강내종양및좌측원위부요관내조영증강이되는좌측원위부요관벽의비후와수신증이확인되었다 (Fig. 2C). 요관벽의비후에대한추가적인소변세포검사상비정형세포가확인되어서요관암이의심되었다. 이에복강내종양및요관벽비후에대해서함께 Vol. 9, No. 2, 2016 182
Incidental Detection of Struma Ovarii on the Whole Body Scan in a Differentiated Thyroid Cancer Patient 수술적치료를하기로하였으며, 수술직전시행한검사상혈중 TSH는 0.04 miu/l, 유리 T4는 21.9 pmol/l, 갑상선글로불린은 3330 μg/l, 항갑상선글로불린항체는 96.4 kiu/l로확인되었다. 복강경하에서질식자궁절제술, 양측난소절제술과좌측요관및신장절제술을시행하였다. 수술후병리조직검사상에서는좌측난소에 7.5 5.8 3.8 cm 크기의성숙낭종성기형종이확인되었으며증식성의갑상선조직으로구성된난소갑상선종이확인되었다 (Fig. 2D). 난소갑상선종의일부분에서는선종성으로증식을보이는부분도관찰되었다 (Fig. 2E). 원위부요관에는침윤성유두상이행성세포암이확인되었다. 수술이후 2개월뒤갑상선호르몬제복용중에시행한검사상혈중 TSH는 0.06 miu/l, 유리 T4는 23.2 pmol/l이었으며, 갑상선글로불린은 3.3 μg/l, 항갑상선글로불린항체는 54.7 kiu/l로확인되었으며별다른합병증없이추적관찰중이다. 고찰 분화갑상선암은갑상선여포상피세포에서발생하는종양으로갑상선암의대부분을차지하고이중유두암종이 85%, 여포암종이 12% 정도를차지한다. 1) 갑상선유두암은조직학적소견에따라고전적인유두암, 변이형유두암으로나누며소포변이유두암은변이형유두암중가장흔한형태중하나로전체갑상선유두암의 9% 에서 22.5% 를차지한다. 6) 이는조직학적으로여포성구조를지니지만세포의핵모양은유두암양상을보이며최근진단빈도가늘어나고있다. 7) 소포변이유두암은양성여포성종양과의세포학적감별이쉽지않다. 이에양성여포성종양에서 NRAS 등의돌연변이가있는경우악성확률이높아돌연변이의동반여부에따라수술적치료여부혹은수술의범위가결정되기도한다. 8) 본환자에서도처음조직검사상여포성종양이확인되었으나 NRAS codon 61번돌연변이가확인되어진단적수술이후소포변이유두암으로확인되었다. 분화갑상선암수술후잔여갑상선제거를위한 I-131 방사성요오드치료는 50년이상시행되어온치료법으로 sodium iodide symporter에의한갑상선조직의요오드섭취가갑상선조직이나분화갑상선암에서선택적인특성을이용한것이다. 9) 방사성요오드는세포내로섭취된뒤수개월에걸쳐이온화방사선 (ionizing radiation) 을방출함으로써세포의사망을유도하여치 료효과를나타낸다. 방사성요오드치료후방사성요오드전신스캔을시행하고있으며이는분화갑상선암의전이여부를확인할수있는민감한검사방법이다. 하지만기대하지않았던부위에서병적방사성요오드의섭취가확인되는경우가있는데두피의모낭염, 침샘염, 부비동염등의염증성병변, Warthin 종양, 유방섬유선종, 심장갑상선종, 난소갑상선종, 점액성낭선종등의일부양성종양과일부폐암, 유방암, 난소암등의악성종양에서도병적방사성요오드섭취가확인될수있다. 4,5) 본증례에서갑상선암이진단된이후 I-131 방사성요오드치료를시행하였고이후시행한방사성동위원소전신스캔에서골반내비정상적인요오드의섭취가확인되어이에대해추가적인검사로 SPECT-CT를시행하였다. SPECT-CT는 SPECT와 CT를동시에시행하여영상을융합하여표시하는방법으로, 방사성요오드전신스캔의정확한해부학적위치를평가할수없는약점을보완할수있다. 10) I-131을이용한전신스캔과 SPECT-CT를동일한환자군에서비교한연구에서 SPECT-CT는약 20% 환자에서림프절병기에있어서이점을나타내었다. 11) 또한같은연구에서전신스캔에서병소가보이지않으나갑상선글로불린이상승되어있는환자에서 SPECT-CT는국소재발, 폐전이, 골격전이등의발견에임상적인도움을주었다. 따라서고위험군환자, 전신스캔에서비특이적요오드섭취가있는경우, 원격전이가의심되는경우, 갑상선글로불린값이상승되어있으나전신스캔에서병소가보이지않는경우등에서유용하게사용할수있을것이다. 성숙낭종성기형은전체난소종양의약 20% 를차지하며대략 5-15% 에서갑상선조직을포함하고있다. 난소갑상선종은갑상선조직이 50% 이상분포할때로정의하고있으며대략 3% 에서악성을보인다. 12) 갑상선조직이포함된성숙기형종은갑상선조직이포함되어있어갑상선호르몬을생산할수도있고전신스캔에서도방사성요오드의섭취가확인된다. 13) 본증례에서수술전시행한혈중 TSH가정상수치보다낮은값을보였으나, 수술전갑상선스캔등의추가적인검사를시행하지않았기때문에성숙기형종에의한 TSH 감소의가능성을명확히확인할수는없었다. 현재성숙기형종에대한치료는질식자궁절제술, 양측난소절제술의근치적수술적치료가우선된다. 본증례는방사성요오드치료후시행한전신스캔에서골반내비정상적섭취가확인되어시행한 SPECT-CT상자궁혹은난소에기형종이확인된드문증례로, 14-16) 정확한병소 183 Int J Thyroidol
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