266 pissn : 1226-2102, eissn : 2005-8918 Case Report J Korean Orthop Assoc 2016; 51: 266-271 http://dx.doi.org/10.4055/jkoa.2016.51.3.266 www.jkoa.org 슬와부낭종으로오인된경골신경초종 민경대 유정우 조우인 황석하 * 순천향대학교부천병원정형외과, * 서울성애병원정형외과 Tibial Schwannoma Mimicking a Popliteal Cyst Kyoung-Dae Min, M.D., Jung-Woo Yoo, M.D., Woo-In Cho, M.D., and Suk-Ha Hwang, M.D.* Department of Orthopedic Surgery, Soonchunhyang University Bucheon Hospital, Bucheon, *Department of Orthopedic Surgery, Sungae Hospital, Seoul, Korea Schwannoma is the most common benign tumor of peripheral nerves and usually appears on the trunk, head and neck, or extremities. A mass arising at popliteal fossa can be misdiagnosed as a popliteal cyst. We report on a rare case of a popliteal schwannoma mimicking a popliteal cyst in a 39-year-old female who showed a clinical presentation similar to that of a popliteal cyst. Diagnosis was delayed until ultrasonographic evaluation was performed due to its anatomical location, the same as that of a popliteal cyst. We describe the clinical significance and ultrasonographic findings of the schwannoma for initial differential diagnosis from a popliteal cyst. Key words: schwannoma, popliteal cyst, ultrasonography 슬와부에종물이만져지는경우보통베이커낭종이가장흔하므로임상적으로증상이경미한경우에는경과관찰을하거나종괴효과 (mass effect) 에따른증상이있는경우특별한검사없이천자를통한감압을하는경우가많다. 저자들은슬와부에서외관상낭종과유사한위치와크기로인해낭종으로오인할수있고, 아직국내에보고된바없는희귀한슬와부경골신경초종을경험하여문헌고찰과함께보고하는바이다. 골손상이의심되었다. 슬와부중앙에는비교적단단하고움직임이적은둥근모양의종괴가촉지되었고압통은없었으며, 우측슬관절단순측면방사선사진에서슬와부에둥근연부조직음영이관찰되었다 (Fig. 1). 먼저흔히볼수있는슬와부낭종으로의 증례보고 39세여자환자가내원 2년전부터발생한우측슬부내측의간헐적통증과약 3개월전인지한슬와부종괴를주소로내원하였다. 주변에서슬와에생긴물혹은그냥두어도된다는이야기를들었고최근종괴의크기변화는느끼지못했다고하였다. 이학적검사상슬관절의내측관절면을따라압통이있어내측반월상연 Received October 29, 2015 Revised November 26, 2015 Accepted December 4, 2015 Correspondence to: Kyoung-Dae Min, M.D. Department of Orthopedic Surgery, Soonchunhyang University Bucheon Hospital, 170 Jomaru-ro, Wonmi-gu, Bucheon 14584, Korea TEL: +82-32-621-5261 FAX: +82-32-621-5017 E-mail: kdmin@schmc.ac.kr Figure 1. Lateral X-ray of the right knee shows a round soft tissue shadow in the popliteal space. The Journal of the Korean Orthopaedic Association Volume 51 Number 3 2016 Copyright 2016 by The Korean Orthopaedic Association 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.
267 Tibial Schwannoma Mimicking a Popliteal Cyst 심하고진단적흡입을고려하여초음파검사를시행하였다. 그러나초음파검사에서후방음영이증강되는타원형의경계가명확한낭성종괴의형태이나내부가점상의결절을포함하는비균질한 (heterogenous) 양상으로, 일반적인슬와낭종과다른소견이었다 (Fig. 2A). 함께시행한도플러초음파검사에서는종괴와종괴주위로의미있는혈류증가는관찰되지않았으나종괴가슬와정맥을압박하는양상이었다 (Fig. 2B). 종괴의근위부와원위부에서연결된방추형의꼬리 (tail) 영상이관찰되었고 (Fig. 2C), 타진시하퇴부의저린감을호소하여낭종이아닌신경인성연부종양이의심되었으므로천자는하지않았다. 관절내반월상연골의이상여부와종괴의성상을자세히확인하기위하여조영증강자기공명영상검사 (magnetic resonance imaging, MRI) 를시행하였다. MRI 소견상후외측에 5 4 3 cm 크기의경계가명확한타원형의종괴가관찰되었고, 종괴는 T1-weighted image에서저신호강도 (Fig. 3A), T2-weighted image에서고신호강도를보였으며 (Fig. 3B), 내부에 T2-weighted image에서저신호, T1-weighted image에서고신호를보이는결절성병변들을포함하고있었다 (Fig. 3C). 종괴는근위및원위부에서경골신경과방추형으로연결되어있었으며 (Fig. 3A) 슬와정맥을압박하고있었다 (Fig. 3B). 이와함께관절내에서는내측반월상연골후각부의수평파열도동반되어내측부통증의원인으로생각되었다. 종괴는신경초종이강력히의심되었고타진시슬와부아래로방사되는 Tinel 징후 (Tinel s sign) 양성소견을보여조직병리학적확진및치료를위하여수술을계획하였다. 먼저전신마취후앙와위에서관절경으로 A B C Figure 2. Ultrasonographic findings showing a well-defined, hypoechoic oval shaped nodular mass filled with nonhomogeneous components (A) and tibial nerve fascicular continuity at its proximal end (B). (C) Compression of the popliteal vein was observed at the bottom of the mass. A B C Figure 3. Magnetic resonance imaging findings of the mass. Saggital T1- (A), T2- (B), and axial T2 contrast enhanced-weighted images demonstrating a well-marginated mass with hypointense (A), hyperintense (B), inner heterogeneous (C) signals, respectively.
268 Kyoung-Dae Min, et al. 내측반월상연골절제술을시행한다음, 복와위로자세를바꾸었다. 슬와부종괴바로위로피부를 S-형으로절개하고종괴주변을박리하여노출시켰다. 종괴를덮고있는신경막 (Fig. 4A) 을종으로약간절개한후살살밀어내면서박리하여조심스럽게낭성조직만을적출함으로써 (enucleation) 주위신경조직을보존하였다 (Fig. 4B). 낭성종괴를분리하고남은공간의신경조직을확인하니경골신경의일부와경골신경에서분지하여하퇴로주행하는감각신경인후방경피신경 (posterior cutaneous nerve to calf) 이종물표면에연결되어감싸고있던양상이었다. 조직병리학적검사에서신경초종으로진단되었고 (Fig. 5A), 면역세포화학적염색에서 S-100 단백염색양성소견을보였다 (Fig. 5B). 술후 4일째에퇴 원하였고술후하퇴후방부의약간의저린감을호소하였으나 3 개월추시에서호전되었으며, 6개월추시시수술부위통증이나신경학적증상은호소하지않았고양호한임상결과를보였다. 고찰 신경초종은신경초에서발생하는가장흔한종양이면서악성으로변화되는경우는거의없는것으로알려져있다. 1) 임상적으로 20-50세사이의연령에서주로발생하고, 남녀간의성비에있어서는균등한분포를보이는것으로보고되었다. 1) 신경초종은대부분천천히자라고낭, 섬유화, 석회화등을형성하는퇴행성변 A B Figure 4. Photograph of the right popliteal fossa mass at surgery, which confirmed a well-defined mass originating from the tibial nerve branch (A) and an enucleated mass, 5 4 3 cm in size (B). A B Figure 5. Pathological diagnosis was schwannoma. (A) Tumor cells have ill-defined cytoplasm and nuclear palisading (H&E, 400). (B) Positive result of immunohistochemical staining for S-100 protein ( 200). Table 1. Reported Cases of Schwannoma Located at the Popliteal Fossa Author Year No. of case Origin Size Komurcu et al. 2) 2013 1 Tibial nerve 4 2 cm Shariq et al. 3) 2012 1 Common peroneal nerve Undescribed Andrychowski et al. 4) 2012 1 Common peroneal nerve Undescribed Maraziotis et al. 5) 2005 2 Sciatic nerve Undescribed
269 Tibial Schwannoma Mimicking a Popliteal Cyst 화를보이기도한다. 슬와부에서는매우드물게보고되었고, 특히경골신경에서발생한경우는 Komurcu 등 2) 의보고가유일하며 (Table 1) 2-5) 국내에서보고된바는없다. 슬와부의신경초종은비록매우드물게발생하지만슬와부에서가장흔하게볼수있는슬와낭종 (Baker s cyst) 과감별이필요하다는점에서임상적의의가있다. 슬와부에서발생하는경우낭종과의공통점은발생위치가같고, 모양이둥글고각각다양한크기를가지며특히피하지방층이두꺼운경우촉지시강도 (consistency) 가유사하고피하에서쉽게움직이지않는다는점이고, 차이점은낭종이팽창하는경우에는단단하게느껴지기도하지만신경초종이보다단단하고, 압통이있을수있으며자극시신경증상을보일수있다는점이다. 6) 따라서압통과촉진시이환된신경분포지역에감각이상을동반한통증이유발되는 Tinel 징후등을통해임상적으로신경초종을감별할수있다. 1,6) 초음파검사는이러한낭성종물의경우초기에쉽게감별할수있는좋은진단방법이다. 7,8) 감별점으로보통슬와낭종은초음파소견상내부에균일한낭성물질로채워져있으며압박시내부저음향의물질이움직이는반면, 신경초종의경우내부가균일하지않으며압박시유동적이지않고양쪽끝이신경과접하여편심성으로신경과연결된꼬리형태의연결부위를확인할수있다. 본증례에서도종괴의근위와원위부에서경골신경과편심성으로위치하여연결되어있는양상을관찰할수있었다. 도플러초음파같은경우에는 King 등 7) 은몇몇증례에서종괴주위로혈류가증가된소견을보였다고하였으나 Simonovský 8) 는도플러초음파상종괴와종괴주위의혈류가종괴의감별에큰의미는없는것으로보고하였다. 본증례의경우에서는도플러초음파검사에서종괴와종괴주위로의미있는혈류증가는관찰되지않았고종괴가주위의슬와정맥을압박하는양상이었다. 저자들의경우초음파소견만으로신경초종이강력히의심되었지만관절내측통증이있어관절내연골상태의확인이필요했고종물의성상과연결부위를확인하여수술을계획하기위하여 MRI를시행하였다. MRI에서는 T1-weighted image에서등신호또는저신호강도를보이고, T2-weighted image에서는주로비균질하면서고신호강도를보이며, 이는종괴의낭성변화에의한것으로생각된다. 하지만이런신호강도의형태로는양성과악성의신경종양을완전히구분할수없으며 Stull 등 9) 과 Suh 등 10) 은 MRI가고립성신경섬유종으로부터신경초종을감별진단하는데효과적이지못하다고보고하기도하였다. 조직학적검사에서는 S-100에서양성소견을보이는방추상의신경초세포 (Schwann cell) 를확인하여진단이가능하며, 종양내부의괴사나세포의이형성, 미분화가발견되는지확인하여악성과의감별이가능하다고한다. 2) 신경초종은대부분양성종양이며완전절제가우선적치료방 법이다. 신경초종의예후는다양하지만대부분신경막에편심성으로위치하기때문에심각한신경손상이나신경학적결손은흔치않다. 또한수술후발생한기능적결손이나감각결손은대부분짧은기간내에회복되는것으로알려져있다. 6) 결론적으로슬와부종괴의경우임상적으로낭종이가장흔하므로그해부학적위치로인해속단하여간과할수있으므로본증례와같이다른종양의가능성도항상염두에두어야할것이다. 이때초음파검사는조기에슬와부종물을감별하는데간편하고효과적인검사라생각된다. CONFLICTS OF INTEREST The authors have nothing to disclose. REFERENCES 1. Kim JI, Kim UJ, Moon TY, Lee IS, Song YS, Choi KU. Diagnostic value of MRI in schwannoma. J Korean Bone Joint Tumor Soc. 2014;20:60-5. 2. Komurcu E, Golge UH, Kaymaz B, Erdogan N. Popliteal schwannoma mimicking baker cyst: an unusual case. J Surg Case Rep [Internet]. 2013 [cited 2013 Aug 29];2013. doi: 10.1093/jscr/rjt066. Available from: http://jscr.oxfordjournals.org/content/2013/8/rjt066.long 3. Shariq O, Radha S, Konan S. Common peroneal nerve schwannoma: an unusual differential for a symptomatic knee lump. BMJ Case Rep [Internet]. 2012 [cited 2012 Dec 3];2012. doi: 10.1136/bcr-2012-007346. Available from: http://casereports.bmj.com/content/2012/bcr-2012-007346.long 4. Andrychowski J, Czernicki Z, Jasielski P. Schwannoma of the common peroneal nerve. A differential diagnosis versus rare popliteal cyst. Neurol Neurochir Pol. 2012;46:396-400. 5. Maraziotis T, Panagiotopoulos E, Panagiotopoulos V, Panagiotopoulos K. Neurilemoma of the popliteal fossa: report of two cases with long subclinical course and misleading presentation. Acta Orthop Belg. 2005;71:496-9. 6. Green DP, Hotchkiss RN, Pederson WC, Wolfe SW. Green's operative hand surgery. 5th ed. Philadelphia: Churchill Livingstone; 2005. 2211-64. 7. King AD, Ahuja AT, King W, Metreweli C. Sonography of peripheral nerve tumors of the neck. AJR Am J Roentgenol. 1997;169:1695-8. 8. Simonovský V. Peripheral nerve schwannoma preoperatively diagnosed by sonography: report of three cases and discus-
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271 pissn : 1226-2102, eissn : 2005-8918 Case Report J Korean Orthop Assoc 2016; 51: 266-271 http://dx.doi.org/10.4055/jkoa.2016.51.3.266 www.jkoa.org 슬와부낭종으로오인된경골신경초종 민경대 유정우 조우인 황석하 * 순천향대학교부천병원정형외과, * 서울성애병원정형외과 신경초종은말초신경에서발생하는가장흔한양성종양으로주로두경부, 체간및상하지에호발한다. 슬와부에발생하는경우는매우드물며슬와부낭종으로오인되기쉽다. 저자들은 39세여자환자에서슬와낭종과유사한해부학적위치와임상양상으로인해진단이지연되었던경골신경분지에서의거대신경초종의드문증례를경험하여슬와낭종과의감별을위한초기초음파적소견과함께임상적중요성을보고하고자한다. 색인단어 : 신경초종, 슬와낭종, 초음파 접수일 2015 년 10 월 29 일수정일 2015 년 11 월 26 일게재확정일 2015 년 12 월 4 일책임저자민경대 14584, 부천시원미구조마루로 170, 순천향대학교부천병원정형외과 TEL 032-621-5261, FAX 032-621-5017, E-mail kdmin@schbc.ac.kr 대한정형외과학회지 : 제 51권제 3호 2016 Copyright 2016 by The Korean Orthopaedic Association 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.