Successful Diagnosis of a Thymoma by Endobronchial Ultrasound-guided Transbronchial Needle Aspiration: A Report of Two Cases

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1 CASE REPORT Successful Dignosis of Thymom y Endoronchil Ultrsound-guided Trnsronchil Needle Aspirtion: A Report of Two Cses Ysushi Yoshid 1, Msto Singyoji 1, Hironori Ashinum 1, Meiji Itkur 1, Toshihiko Iizs 1 nd Koichiro Ttsumi 2 Astrct We herein report two cses of thymoms dignosed y endoronchil ultrsound-guided trnsronchil needle spirtion (EBUS-TBNA). In oth cses, the tumor ws djcent to the centrl irwy. Therefore, we ttempted to perform EBUS-TBNA in order to otin specimens for histopthologicl exmintion, which resulted in dignosis of thymom. In one cse, surgicl resection ws conducted nd the histologicl evlution of the resected specimen confirmed thymom type AB, consistent with the histology from the EBUS- TBNA specimen. As sfe nd minimlly invsive procedure, EBUS-TBNA my e considered for the dignosis of medistinl tumors, including thymom. Key words: thymom, suclssifiction, endoronchil ultrsound-guided trnsronchil needle spirtion (Intern Med 54: , 2015) (DOI: /internlmedicine ) Introduction Thymom is the most common tumor type in the nterior medistinl region due to the norml thymus position. However, to mke dignosis of thymom from fine needle iopsies, such s endoronchil ultrsound-guided trnsronchil needle spirtion (EBUS-TBNA), is chllenging due to the need to differentite from mny diseses. Moreover, thymom my e suclssified into six types ccording to the morphology of the epithelil cells nd the rtio of lymphocytes nd epithelil cells; these types re ssocited with specific clinicl fetures nd vrying degrees of ggressiveness (1). Therefore, it is impertive to decide the sutype of thymom efore plnning the tretment strtegy. However, fine needle spirtion does not provide sufficient specimen for n dequte suclssifiction (2). Conversely, recent report suggests tht EBUS-TBNA llows the dignosis nd further suclssifiction of thymom (3). We herein present two cses of thymom dignosed y EBUS-TBNA. In one cse, the dignosis of thymom nd the sutype were confirmed y histology of the resected specimen. Cse 1 Cse Reports A 68-yer-old womn with hypertension, ronchil sthm nd hypothyroidism presented with n norml right medistinl shdow on chest X-ry tken during regulr helth check-up. A contrst-enhnced computed tomogrphy (CT) scn showed mssive tumor lrger thn 135 mm in the medistinl region (Fig. 1) nd she ws referred to the Thorcic Division of Chi Cncer Center. A physicl exmintion reveled no remrkle findings nd lortory dt, including tumor mrkers, were within the norml rnges, except slight elevtion of thyroid stimulting hormone (TSH) to 5.97 μu/ml (norml rnge: 0.35 to 4.94) nd free thyroxine (FT4) to 1.56 ng/dl (0.7 to 1.48) ws oserved. To further chrcterize this tumor, mgnetic resonnce imging (MRI) of the chest ws performed, which demonstrted heterogeneous medistinl tumor nd n in- Division of Thorcic Disese, Chi Cncer Center, Jpn nd Deprtment of Respirology, Grdute School of Medicine, Chi University, Jpn Received for puliction June 15, 2014; Accepted for puliction Ferury 2, 2015 Correspondence to Dr. Ysushi Yoshid, pmdht627@yhoo.co.jp 2735

2 Intern Med 54: , 2015 DOI: /internlmedicine c d Figure 1. Cse 1. : Contrst-enhnced chest CT showing homogeneous medistinl tumor djcent to the trche. : An xil T2-weighted MR imge of the chest showing medistinl tumor with irregulr mrgin nd heterogeneous intensity nd invsion into the superior ven cv (rrows). c: A PET/CT scn showing the remrkle FDG uptke in the tumor. d: Endoronchil ultrsound showing needles (rrows) penetrted through medistinl tumor with heterogeneous echogenicity. vsion of the superior ven cv on the T2-weighted imge (Fig. 1). Whole ody 18F-2-deoxy-fluoro-D-glucose (FDG) positron emission tomogrphy (PET) ws dditionlly performed, which demonstrted modertely elevted mximum stndrdized uptke vlue (SUVmx) of 8.35 to 9.08, suggesting mlignncy (Fig. 1c). The tumor ppered to e in contiguity with the right min ronchus. Therefore, we proceeded to conduct EBUS-TBNA of the medistinl tumor nd endoronchil ultrsound indicted heterogeneous pttern (Fig. 1d). A cytologicl exmintion of the iopsy showed epithelil cells nd numerous smll lymphocytes in Hemtoxylin nd Eosin (H&E) stining nd meshwork of epithelil cells in immunohistochemicl stining of AE1/AE 3, thus leding to dignosis of thymom (type B1 or B2) (Fig. 2). Due to the tumor size nd the invsion to mjor vessels, surgery or rdiotherpy were not indicted. The ptient declined our recommendtion of chemotherpy nd insted selected pllitive cre. Cse 2 A 71-yer-old womn who hd een under tretment for hypertension ws referred to the Thorcic Division of Chi Cncer Center ecuse chest X-ry tken during regulr helth check-up showed right upper medistinl tumor. A contrst-enhnced CT scn demonstrted medistinl tumor mesuring mm with heterogeneous hyperdensity locted djcent to the trche (Fig. 3). The physicl exmintion reveled no norml findings nd lortory dt showed mild elevtion of lctte dehydrogense (LDH) to 230 IU/L (norml rnge: 80 to 200) nd silyl Lewis-X ntigen (SLX) to 56 U/mL (up to 38). The susequent FDG-PET scn disclosed mildly elevted SUVmx of 3.59 only in the medistinl tumor (Fig. 3). We performed EBUS-TBNA nd endoronchil ultrsound reveled homogeneous echogenity (Fig. 3c). The cytologicl exmintion showed polygonl cells nd spindle cells ggregted nd dispersed mong the smll lymphocytes in H&E stining nd network of epithelil cells nd immunohistochemicl stining of cytokertin 19, suggestive of thymom, possily type AB (Fig. 4). The ptient underwent surgicl excision of the tumor. The resected tumor mesured cm. The histologicl exmintion of the resected tumor confirmed dignosis of thymom type AB, which ws consistent with the dignosis sed on the EBUS-TBNA specimen (Fig. 5). The tumor ws nerly completely encpsulted mcroscopiclly nd microscopiclly, ut prtil trnscp- 2736

3 Intern Med 54: , 2015 DOI: /internlmedicine Figure 2. Cse 1. : Cytologicl findings of iopsy otined y endoronchil ultrsound-guided trnsronchil needle spirtion showing epithelil cells with cler nuclei lrger thn the lymphocytes nd numerous smll lymphocytes (Hemtoxylin nd Eosin stining, 40 ). : Immunocytochemicl stining for cytokertin AE 1/AE 3 showing meshwork of epithelil cells (20 ). c Figure 3. Cse 2. : Contrst-enhnced chest CT showing heterogeneous medistinl tumor displcing the trche gretly to the left. : A PET/CT scn showing the insignificnt uptke in the tumor. c: Endoronchil ultrsound showing needles (rrows) penetrted through medistinl tumor with comprtively low echoic pttern. sulr invsion ws found (Msok stge II). The ptient did not undergo dditionl irrdition or chemotherpy, s recommended y the guideline. She showed no sign of recur- rence two nd hlf yers fter surgery. 2737

4 Intern Med 54: , 2015 DOI: /internlmedicine Figure 4. Cse 2. : Cytologicl findings of iopsy otined y endoronchil ultrsound-guided trnsronchil needle spirtion showing polygonl cells nd spindle cells with ple chromtin nd inconspicuous nuclei, ggregted (center of the figure) nd dispersed mong smll lymphocytes (Hemtoxylin nd Eosin stining, 40 ). : Immunocytochemicl stining for cytokertin 19 showing network of epithelil cells (20 ). Figure 5. Cse 2. : Microscopic findings showing ggregtion of spindle cells hving dispersed chromtin nd inconspicuous nucleoli, with few lymphocytes in the left lower re nd reltively lrger numer of smll lymphocytes in right upper re (Hemtoxylin nd Eosin stining, 40). : Immunohistochemicl stining for cytokertin 19 showing reticulr meshwork of epithelil cells ( 20). Discussion The EBUS-TBNA method is utilized not only for the lymph node stging of lung cncer, ut lso for the dignosis of other mlignnt (4) nd enign diseses (5, 6). Compred to the conventionl methods, including CT-guided fine needle spirtion, medistinoscopy nd video-ssisted thorcoscopy (VATS), EBUS-TBNA provides sfer nd less invsive pproch for smpling tissues even in the medistinl region (6). Only limited numer of cses hve een reported in which thymom ws successfully dignosed y EBUS-TBNA (3, 6), ecuse it hs een considered chllenging to dignose thymom y EBUS-TBNA (7, 8). The most criticl disdvntge of EBUS-TBNA is tht very smll volume of the entire tumor cn e smpled. The tiny specimens otined from EBUS-TBNA my preclude precise dignosis due to the heterogeneous nture of medistinl tumors nd my not llow sutyping of thymom, which is importnt for determining the prognosis (1) s well s the tumor stge (9). Another chllenging reson is the fct tht thymom is reltively rre tumor with n incidence of 0.15 per 100,000 popultion, nd cytopthologist my not hve sufficient experience to mke n ccurte di- 2738

5 Intern Med 54: , 2015 DOI: /internlmedicine gnosis (8). Consequently, only hospitls tht hve skillful cytopthologists nd pulmonologists, who cn otin n dequte mount of specimens y EBUS-TBNA re le to utilize EBUS-TBNA for mking n ccurte dignosis of thymom. Moonim nd collegues (3) reported in detil the successful dignosis nd suclssifiction of three cses of thymom using EBUS-TBNA. In two of the three cses, surgicl resection ws conducted nd histologicl exmintion of the resected tumor confirmed the results otined from the EBUS-TBNA smples. Regrding the suclssifiction of thymom, these two cses were types B1 nd B2. These sutypes re reltively simple to suclssify compred to the present cse of type AB. Remrkly, we were le to detect the type A component despite the minute EBUS- TBNA smple, resulting in dignosis of type AB. In prctice, however, n ccurte suclssifiction is difficult using smll prtil smples collected y EBUS-TBNA. The EBUS-TBNA technique my llow the suclssifiction of thymom in cses of type B thymom. The conventionl methods for investigting medistinl mss include CT-guided fine needle spirtion, medistinoscopy, nd VATS, which my led to some complictions. Medistinoscopy nd VATS re performed in the operting room under generl nesthesi nd re therefore more invsive thn CT-guided fine needle spirtion. In generl, the most common complictions of CT-guided fine needle spirtion re pneumothorx nd hemorrhge. In the medistinl region, the procedure hs to e conducted with specil ttention to void lrge vessels, including the internl thorcic rtery, scending ort, nd pulmonry rtery, ecuse of the possile life-thretening complictions. Additionlly, reports of needle trck seeding fter iopsy of thymom must e noted (10). EBUS-TBNA is novel nd minimlly invsive technique, nd the compliction rte is considered to e low. However, ccording to recent ntionwide survey of the complictions ssocited with EBUS-TBNA in Jpn, the incidence of infectious complictions ws higher thn expected. Therefore, prticulr ttention hs to e given to the occurrence of medistinitis tht my led to severe conditions necessitting tretment y rod-spectrum ntiiotics nd surgery (11). Conditions tht require the use of prophylctic ntiiotics should e considered, since no routine prophylctic ntiiotic is currently recommended. Sdohr et l. reported tht MRI of thymom provides useful informtion in differentiting low-risk thymoms from high-risk thymoms nd thymic crcinoms (12). In cse 1, the findings of the medistinl tumor on MRI were n irregulr contour shpe, incomplete cpsule nd gret vessel invsion, suggestive of high-risk thymom or thymic crcinom; therefore, the thymom in cse 1 ws proly not due to type B1. Although the findings of heterogeneous nd homogeneous echogenity of EBUS my lso contriute to the differentition of low-risk thymoms from high-risk thymoms nd thymic crcinoms, future dt must e ccumulted to determine its usefulness. In summry, we herein reported two cses of thymom in which EBUS-TBNA successfully led to n ccurte dignosis with no complictions. EBUS-TBNA is considered to e less invsive method compred to conventionl CT-guided fine needle spirtion, medistinoscopy nd VATS, especilly when the tumor is djcent to the trche or min ronchus. EBUS-TBNA my e considered for the dignosis of medistinl mss, nd specil cre must e tken to prevent medistinitis nd other infectious complictions. The uthors stte tht they hve no Conflict of Interest(COI). References 1. Trvis WD, Brmill E, Müller-Hermelink HK, Hrris CC. World Helth Orgniztion Clssifiction of Tumours, Pthology nd Genetics: Tumours of the Lung, Pleur, Thymus nd Hert. IARC, Lyon, 2004: Mrchevsky A, Mrx A, Stroel P, et l. Policies nd reporting guidelines for smll iopsy specimens of medistinl msses. J Thorc Oncol 6: , Moonim MT, Breen R, Gill-Brmn B, Sntis G. Dignosis nd suclssifiction of thymom y minimlly invsive fine needle spirtion directed y EBUS. Cytopthology 23: , Kennedy MP, Jimenez CA, Bruzzi JF, et l. Endoronchil ultrsound-guided trnsronchil needle spirtion in the dignosis of lymphom. Thorx 63: , Grwood S, Judson MA, Silvestri G, Hod R, Frig M, Doelken P. Endoronchil ultrsound for the dignosis of pulmonry srcoidosis. Chest 132: , Ysufuku K, Nkjim T, Fujiwr T, Yoshino I, Keshvjee S. Utility of endoronchil ultrsound-guided trnsronchil needle spirtion in the dignosis of medistinl msses of unknown etiology. Ann Thorc Surg 91: , Ali SZ, Erozn YS. Thymom. Cytopthologic fetures nd differentil dignosis on fine needle spirtion. Act Cytol 42: , Zkowski MF, Hung J. The role of fine needle spirtion cytology in the dignosis nd mngement of thymic neoplsi. J Thorc Oncol 5(10 Suppl 4): S281-S285, Msok A, Monden Y, Nkhr K, Tniok T. Follow-up study of thymoms with specil reference to their clinicl stges. Cncer 48: , Wu CC, Mher MM, Sheprd JA. Complictions of CT-guided percutneous needle iopsy of the chest: prevention nd mngement. AJR Am J Roentgenol 196: W678-W682, Asno F, Aoe M, Ohski Y, et l. Complictions ssocited with endoronchil ultrsound-guided trnsronchil needle spirtion: ntionwide survey y the Jpn Society for Respirtory Endoscopy. Respir Res 14: 50, Sdohr J, Fujimoto K, Muller NL, et l. Thymic epithelil tumors: Comprison of CT nd MR imging findings of low-risk thymoms, high-risk thymoms, nd thymic crcinoms. Eur J Rdiol 60: 70-79, The Jpnese Society of Internl Medicine