{"paper_id":"8dc4c8dd-9dfd-47b9-84e2-7ecf88208532","body_text":"THIEME\n58 Case Report \nPeriureteric Mass in a Treated Case of Papillary \nCarcinoma of Thyroid: A Diagnostic Dilemma\nSushil Panbude 1 Archi Agrawal 2 Shubhada Kane 3 Anil D’Cruz4 Supreeta Arya 1\n1Department of Radiodiagnosis, Tata Memorial Hospital, Mumbai, \nMaharashtra, India\n2Department of Nuclear Medicine, Tata Memorial Hospital, Mumbai, \nMaharashtra, India\n3Department of Pathology, Tata Memorial Hospital, Mumbai, \nMaharashtra, India\n4Department of Surgical Oncology, Tata Memorial Hospital, \nMumbai, Maharashtra, India\nreceived \nSeptember 2, 2018\naccepted after revision \nOctober 28, 2018\nAddress for correspondence  Supreeta Arya, MD, DMRD, \nDNB (Radio-diagnosis), Department of Radiodiagnosis, \nTata Memorial Hospital, Mumbai 400012, Maharashtra, India \n(e-mail: supreeta.arya@gmail.com).\nEndometriosis is the presence of normal endometrial glands and stroma outside \nthe endometrium, seen in women in the reproductive age group. Endometriosis  is \ncommon in the pelvis in the pouch of Douglas, rectum, urinary bladder, and uterosacral  \nligaments . Although extrapelvic endometriosis is uncommon, endometriosis  at \nextrapelvic sites such as the gastrointestinal tract, urinary tract, lung, skin, brain, and \nscar site has been reported and can mimic other benign and malignant lesions. It is a \ndifficult diagnosis when patients have a preexisting neoplasm as metastasis can be a \ndifferential. The clinical history, imaging features, and a strong suspicion of this entity \nin the reproductive age group help accurate diagnosis of this entity. We present a rare \ncase of deep pelvic (periureteral) endometriosis in a 41-year-old woman with history \nof papillary carcinoma of the thyroid gland causing diagnostic dilemma on imaging \nand histopathology and also discuss briefly the imaging findings of endometriosis.\nAbstract\nKeywords\n ► endometriosis\n ► extrapelvic\n ► periureteral\nJ Gastrointestinal Abdominal Radiol ISGAR 2019;2:58–63\nDOI https://doi.org/  \n10.1055/s-0039-1677773\n©2019 Indian Society of \nGastrointestinal and Abdominal \nRadiology\nCase History\nA 41-year-old woman, a known case of papillary carcinoma \nof the thyroid, post total thyroidectomy was on regular \nsurveillance at a tertiary referral oncology center with \nultrasonography (US) of the neck and serum thyroglobulin \nassessment for 4 years. Histopathology report revealed \nclassic type of differentiated papillary carcinoma of the \nleft lobe of the thyroid with uninvolved regional nodes. \nMaximum diameter of tumor was 1.1 cm. Lymphovascular \nemboli and perineurial invasion were absent. Extrathyroidal \nextension was not seen.\nFour months after the 4-year follow-up visit revealed no \nevidence of locoregional recurrence, the patient suddenly \npresented with urinary frequency, left lower abdomi -\nnal pain, anorexia, and weakness. Incidentally, she had \na history of Koch’s abdomen 8 years before for which she \nhad received treatment. A US of the abdomen and pelvis \nwas performed and revealed mild left hydronephrosis \nand an ill-defined small mass in the left hemipelvis. No \nother abnormality was evident. A multidetector computed \ntomography (MDCT) study of the abdomen and pelvis \nwas performed on Lightspeed 16 slice, GE machine. \nContrast-enhanced CT scan was acquired in venous phase \nwith 90 cc of iodinated non-ionic contrast (iopamidol) \ninjected at a rate of 2.5 mL/s. Images were acquired with \n5 mm thickness, and sagittal and coronal reconstructions \nwere performed using retro-reconstructed 1.25 mm thick \nslices. It showed mild left hydronephrosis due to narrow -\ning of an approximately 2-cm-long segment of lower third \nof the left ureter due to compression by an extrinsic mass \nlocated medial to the ureter ( ►Fig. 1 ). The mass measured \n3.0 × 2.1 cm and showed ill-defined margins with adjacent \nfat stranding. The mass extended into the region between \nthe left external and internal iliac veins, but the vessels were \nfree. It appeared separate from the left ovary and uterus. It \nshowed progressive enhancement on venous and delayed \nPublished online: 2019-06-24\n\n59\nPeriureteric Mass in a Treated Case of Papillary Carcinoma of Thyroid  Panbude et al.\nJournal of Gastrointestinal and Abdominal Radiology ISGAR   Vol. 2   No. 1/2019\npostcontrast images. The ureter proximal to the mass \nshowed dilatation, and the entire proximal ureter showed \nmucosal enhancement. Urinary bladder, left terminal ureter, \nand entire right ureter appeared normal. Uterus showed a \ncontraceptive device in situ, but it was otherwise normal. \nBoth the ovaries were normal in size but showed multiple \nperipherally arranged follicles. The differential diagnosis on \nCT included fibromatosis or nodal disease due to relapsed \ntuberculosis. Because serum thyroglobulin was normal \n(< 5 ng/mL), the possibility of metastasis from papillary \ncarcinoma thyroid was considered remote. Following CT, the \npatient underwent ureteroscopy with double J (DJ) stenting \nto relieve the ureteric obstruction. Ureteroscopy revealed no \nmucosal lesion and confirmed narrowing due to extrinsic \ncompression. Urine cytology was normal.\nMagnetic resonance imaging (MRI) of the pelvis \nwas ordered to further characterize the mass. MRI was \n performed on GE Signa HDxt 1.5T machine.  Sequences \nperformed are described in ►Table  1. On MRI, an elon -\ngated soft tissue intensity lesion showing two nodular, \n dumbbell-shaped components was seen medial to the left \nlower ureter just below the pelvic brim reaching up to the \nposteromedial wall of left  external iliac vein. There was focal \nthickening of the adjacent pelvic fascia. The lesion appeared \nhypointense on T1W sequence. On T2W sequences, the  \nanterior component appeared more hyperintense whereas  \nFig. 1  Axial (A), coronal (B), sagittal (C), and oblique (D) reformatted multidetector computed tomography (MDCT) images in maximum-intensity \nprojection in the delayed phase showing soft tissue density mass medial to the left distal ureter causing extrinsic compression of the left ureter \n(red arrow) near the left sacroiliac joint (SI) joint with upstream dilatation of the ureter (yellow arrow). Asterisk (*) represents urinary bladder.\n\n\n60\nPeriureteric Mass in a Treated Case of Papillary Carcinoma of Thyroid  Panbude et al.\nJournal of Gastrointestinal and Abdominal Radiology ISGAR   Vol. 2   No. 1/2019\nthe posterior component was of dark signal ( ►Fig.  2 ).  \nThere was no evidence of diffusion restriction. The lesion \nwas distinct from the left ovary, fallopian tube, and uterus. \nContrast-  enhanced sequences were not performed. The dif -\nferential diagnosis on MRI included nodal disease due to \nrelapsed tuberculosis, retroperitoneal fibrosis (RPF), desmoid \ntumor, deep pelvic endometriosis, and amyloidosis with a  \nremote possibility of metastasis from thyroid primary.\nPositron emission tomography–computed tomography \n(PET-CT) was ordered to look for more easily accessible sites \nfor biopsy. PET-CT was performed on Philips Gemini TOF \n16 machine after intravenous administration of radiolabeled \nglucose 2-deoxy-2-(18F) fluoro-D-glucose (FDG) (in a dose of \n3–5 MBq/kg) and scan obtained 1 hour after the injection of \nradioactive FDG. PET-CT scan showed increased uptake in both \nthe nodular components of the mass with SUV of 7–8 (►Fig. 3). \nThere was no other evidence of active disease elsewhere, \nincluding in the thyroid bed or neck nodes. CT-guided fine-  \nneedle aspiration cytology (FNAC) was performed instead of \nbiopsy due to the proximity of the mass to the vessels.\nAspiration cytology material was scanty. The pathologist \nnoted three sheets of glandular epithelial cells. These showed \nbland nuclei with pale chromatin and occasional intranuclear \ngrooves. These glandular epithelial cells did not appear to be \nmesothelial cells or carcinoma cells. However, few scattered \nstromal cells were noted outside the sheets ( ►Fig.  4). The \npathologist considered the possibility of endometriosis in \nthis situation. Because extra material was not available, FNAC \nsmears were destained and immunocytochemistry (ICC) \nwas performed to confirm the endometrial origin. On ICC \nthe epithelial cells showed positivity for ER, PAX8, and WT1 \nand negative for TTF1 (more markers could not be asked for). \nMullerian origin was confirmed on ICC, and diagnosis of \nureteric endometriosis was favored by the pathologist in this \nfemale patient of reproductive age group presenting with \nextraureteric compression.\nAfter the pathologist favored the diagnosis of endometri -\nosis, a multidisciplinary meeting was convened involving the \ntreating surgical oncologist, uro-oncologist, gyne-oncologist, \nradiologist, and pathologist. The imaging findings were \nreviewed carefully, and a final preoperative radiopathologic \ndiagnosis of deep pelvic endometriosis causing extrinsic \nureteral compression was considered, although the patient \ndid not have a typical history that suggested endometriosis \nand her gynecologist did not concur with this diagnosis. The \npatient underwent surgical excision of the lesion at a general \nhospital, and the postoperative histopathologic examination \nshowed findings suggestive of endometriosis.\nDiscussion\nPapillary thyroid cancer is the most common well-  \ndifferentiated thyroid cancer contributing to 85% of all thyroid \nmalignancies.1 Papillary thyroid carcinoma tends to be \nTable 1 MRI sequences performed\nSequence FOV Slice \nthickness\nSlice gap Matrix size \n(frequency encoding \n× phase encoding)\nTE TR Receiver \nbandwidth\nFlip angle \n(in degrees)\nCoronal T2 (BH) 42 6 1 288 × 224 90 1,000 62 90\nAxial T2 FS (RTR) 44 5 1 288 × 244 90 1,000 62 90\nAxial T1 (BH) 44 5 1 288 × 244 5 180 62 90\nAxial FIESTA (BH) 44 5 1 224 × 224 1.8 Autoa 83 70\nDWI (RTR) 46 5 1 128 × 140 68 Autoa 250 Diffusion gradi -\nent applied\nAbbreviations: BH, breath hold; DWI, diffusion-weighted imaging; FIESTA, fast imaging employing steady-state acquisition; FOV, field of view; MRI, \nmagnetic resonance imaging; RTR, respiratory triggered; TE, echo time; TR, repetition time.\naAutocalculated by machine depending on number of slices.\nFig. 2  Axial T1W (A), axial T2W (B), and coronal STIR (C) MRI scans show an elongated mass that is T1 hypointense and T2 heterogeneous \n(long arrows in A and B), compressing the left ureter (thick arrow in B). Mass is hyperintense on STIR but less than the ovary (arrow in C).\n\n\n61\nPeriureteric Mass in a Treated Case of Papillary Carcinoma of Thyroid  Panbude et al.\nJournal of Gastrointestinal and Abdominal Radiology ISGAR   Vol. 2   No. 1/2019\nmultifocal and metastasizes early to the neck nodes.2 Blood-\nborne metastasis to distant sites is rare. Known sites of distant \nspread in papillary thyroid carcinoma include the bone, lung, \nskin, and brain whereas involvement of recurrent laryngeal \nnerve, larynx, pharynx, trachea, and esophagus occurs due to \ndirect infiltration by the tumor.3 There are also reports of distant \nmetastases to the kidney,4 cerebellum,5 skin,6 and esophagus7 in \nthe literature. Though there are many different staging systems, \nthe American Thyroid Association guidelines recommend use \nof the Union for International Cancer Control/American Joint \nCommittee on Cancer (UICC/AJCC) TNM staging system for \ndifferentiated thyroid carcinoma.8 Overall 10-year survival rate \nof locoregional papillary thyroid cancer is greater than 95%. 9 \nTherefore, the treatment for locoregional disease includes total \nthyroidectomy and neck node dissection, followed by ablation \nof the residual thyroid tissue by the I131 radio iodine.\nSerum thyroglobulin level is used as a marker for recurrent \nor residual differentiated thyroid cancer with a reference level \nof less than 5 ng/mL. 10 It is secreted by the normal thyroid \ncells as well as tumor cells. Therefore, in patients with total \nthyroidectomy, serum thyroglobulin level can be a useful \nmarker to look for residual, recurrent, or metastatic disease. \nWhen increased, neck ultrasonogram and 131I or 123I whole-\nbody scans (WBS) are obtained. Some of the differentiated \nthyroid cancers may undergo de-differentiation. 11,12 They \nmay not secrete thyroglobulin, and 131I or 123I scan may be \nnegative. In this case, FDG PET-CT scan is important to rule \nout recurrent or metastatic disease.13\nPoor prognostic factors for papillary thyroid cancer \ninclude age more than 55 years, nodal or distant metastasis, \nextrathyroid tumor extension, and large tumor size at \npresentation.14 This patient was stage I (T1N0M0) at the time \nof surgery with complete surgical excision and also patient \nwas far younger than 55 years.\nStage I (T1N0M0) disease at presentation with absence \nof poor prognostic factors, normal thyroglobulin level, \nand serial negative ultrasound did not favor a diagnosis \nof thyroid metastatic disease based on CT scan. PET-CT \nshowed increased uptake in the periureteral lesion, but \nbecause of the normal thyroglobulin level and absence of \npoor prognostic indicators for papillary thyroid cancer at \nthe time of presentation, thyroid metastasis was still con -\nsidered unlikely. A relapse of tuberculosis was considered \nmore likely.\nOn CT and MRI scans, the mass was periureteral, extrinsic, \nand ill-defined causing ureteral compression and situated \ndeep in the pelvis. Therefore, our differentials included \nentities such as amyloidosis, RPF, tuberculosis, desmoid \ntumor, and endometriosis.\nAmyloidosis can rarely involve the ureter, causing focal or \ndiffuse wall thickening with or without periureteral stranding, \nureteral filling defect, or focal masses.15,16 It does not involve \nthe ureter circumferentially. On imaging, amyloidosis can be \nconfused with malignancy and infection. Therefore, diagnosis \nis mainly on histopathology with characteristic apple-green \nbirefringence under a polarizing microscope. 16 In this case, \nlesion was extrinsic, but with no features of amyloidosis on \nhistopathology.\nRPF is characterized by development of fibrous plaque in \nthe retroperitoneum often encasing the ureter and causing \nobstruction. RPF can be active or chronic. Active RPF shows \nhigh T2 signal intensity and postcontrast enhancement and \nFig. 3  A Positron emission tomography–computed tomography \n(PET-CT) scan shows increased uptake in the dumbbell-shaped \ncomponents of the left periureteral mass (arrows).\nFig. 4  (A) A fine-needle aspiration cytology (FNAC) smear showing two sheets of glandular epithelial cells. Note the background is clear \nPap smear (100×). (B) Smear shows a folded honeycombed sheet of epithelial cells. Few stromal cells are noted in the background (200×). \n(C) Higher magnification reveals crowded glandular epithelial cells showing uniform oval pale nuclei with micronucleoli and occasional \nintranuclear groove. Also note a stray stromal cell outside the epithelial sheet (arrow) (400×).\n\n\n62\nPeriureteric Mass in a Treated Case of Papillary Carcinoma of Thyroid  Panbude et al.\nJournal of Gastrointestinal and Abdominal Radiology ISGAR   Vol. 2   No. 1/2019\nPET uptake. Chronic RPF shows low T2 signal intensity with \nno postcontrast enhancement and no PET uptake. 17,18 Also, \nRPF pulls the ureter medially. In this case, the lesion was T2 \ndark, but it showed uptake on PET-CT scan and there was no \nmedial deviation of the ureter.\nThis patient had history of tuberculosis in the past.  \nTherefore, relapse of tuberculosis was a likely diagnosis. \nPrimary tuberculosis of the ureter causes intrinsic \ninvolvement of the ureter with irregular, ragged wall \nthickening, filling defect, obstruction, and periureteric \ninflammatory changes. Chronic fibrotic stricture causes \nbeaded or corkscrew appearance. Chronic wall thickening \nmay also cause shortening of the ureter (pipestem ureter).19,20 \nIn this patient, lesion was extrinsic with no intrinsic \ninvolvement of the ureteric wall with no shortening, ruling \nout primary ureteral tuberculosis. There was possibility of \ntuberculous nodal involvement that could cause extrinsic \ncompression of the ureter. However, the mass was located \nmedial to the ureter that is an unusual site for nodes. How -\never, it was included in the list of our differentials because \nof the prevalence in India, past history of tuberculosis, and \nthe imaging features. However, on histopathology, absence of \ngranuloma or caseous necrosis ruled out tuberculosis.\nDesmoid tumor belongs to the group of disorder called \nfibromatosis, which are characterized by the fibroblastic \nproliferation without any evidence of inflammation \nor neoplasia. Fibromatosis can be superficial or deep. \nDesmoid tumor belongs to the category of deep fibroma -\ntosis (locally aggressive) and constitutes less than 1% of all \nretroperitoneal tumors. They can be sporadic or familial and \nassociated with familial adenomatous polyposis or Gardner’s \nsyndrome. Desmoid tumor is also responsive to estrogen and \nis more common in women in the reproductive age group \n(10–40 years). Imaging appearances of the desmoid tumors \ndepend on tumor composition (spindle cells, collagen, \nmyxoid matrix). Early tumors have more myxoid component \nwith increasing collagen deposition with advancing stage. \nThey can be well defined or ill defined and have mass effect \non the surrounding organs, for example the ureter, bowel, \netc. On CT scan, they show variable density depending on \nthe composition, hypodense in early tumors becoming \nhyperdense in late stage with increasing collagen deposition, \nand may show moderate to intense contrast enhancement. \nOn MRI, early cellular desmoid tumors with more myx -\noid content appear hyperintense on T2WI, becoming T2 \nhypointense in late stage with low cellularity and increasing \ncollagen deposition.21,22 This patient was in reproductive age \ngroup and also had imaging findings of desmoid tumor as \ndiscussed previously; hence, it was one of our differentials.\nEndometriosis is a rare cause of periureteric mass causing \nproximal hydroureteronephrosis. 23,24 It is seen in women \nin the reproductive age group. Solid endometriosis, which \nis also referred to as deep pelvic endometriosis  or deeply \ninfiltrative endometriosis , is defined by the extension of \nendometrial glands and stroma at least 5 mm beneath \nthe peritoneal surface. 25 Unlike endometriomas, which \ncontain viscous proteinaceous and hemorrhagic contents, \nsolid masses of endometriosis are composed of ectopic \nendometrial gland and stromal cells embedded within dense \nfibrous tissue and smooth muscle. Also, they are usually \nlocated below the pelvic brim. On MRI, relatively acellular \nregions of fibrous tissue and compact smooth muscle have \nintermediate signal intensity on T1-weighted MRI scans and \nlow signal intensity on T2-weighted images. On T2-weighted \nimages, solid endometriotic masses or nodules will appear \nas hypointense masses with irregular, indistinct, or stellate \nmargins due to the presence of abundant fibrous tissue and \nsmooth muscle proliferation. Areas of T2 hyperintensity can \nbe seen within, which likely represent endometrial glands.26,27 \nAdjacent organ invasion (bladder, rectum, or ureter) may also \nbe seen.26 Although the menstrual history did not favor this \ndiagnosis, these findings were seen in this patient, which \nprompted the authors to favor this differential diagnosis \nupon reviewing imaging features at the multidisciplinary \nmeeting. Endometriosis was confirmed on postoperative \nhistopathologic examination.\nEndometriosis is the presence of endometrial gland \nand/or stroma outside the endometrial cavity. It is more \ncommonly seen in infertile and nulliparous women. The \nprevalence of ureteral endometriosis ranges from 0.01 to \n1% of all women with disease. 28 Ureteral endometriosis can \nbe intrinsic or extrinsic. Extrinsic endometriosis involves \nthe adventitia of the ureter and surrounding tissue whereas \nintrinsic ureteral endometriosis involves the muscularis, \nlamina propria, or lumen of the ureter, either from the \ndeep infiltrating periureteral lesion or directly from the \nlymphatic or hematogenous metastasis of the endometrial \ntissue. 26 Extrinsic involvement of the ureter (80%) is more \ncommon than the intrinsic involvement (20%). 29\nThe etiology and pathogenesis of endometriosis is still \nunclear. Several theories have been proposed for etiopatho -\ngenesis of endometriosis. Broadly, these are the theories \nthat propose that implants (1) originate from uterine endo -\nmetrium or (2) arise from tissues other than the uterus. \nThese include metaplastic theory, induction theory, theory \nof embryonic mullerian rests, extrauterine stem or pro -\ngenitor cell theory, benign metastatic theory, and theory of \n retrograde menstruation. 26,30 According to retrograde men -\nstruation theory, viable endometrial tissue refluxes through \nthe fallopian tube and gets deposited in the pelvic organs. \nThis latter theory is favored by the anatomic distribution of \nendometriotic lesions. Superficial implants are more often \nlocated in the posterior compartment of the pelvis and in \nthe left hemipelvis. 31 The terminal part of the lower ureter \nis first related to the posterior border of the ovary and then \nlies in the uterosacral ligament, both being common sites for \nendometriosis. In this case, the implant was on the left side \nand posteriorly located involving the terminal lower ureter. \nHowever, surprisingly the patient had no history suggesting \nendometriosis. She had also completed her family 10 years \nbefore and was asymptomatic since then.\nConclusion\nThe occurrence of a second benign lesion baffling the clinician \nin a treated case of cancer is not an infrequent phenomenon \n\n\n63\nPeriureteric Mass in a Treated Case of Papillary Carcinoma of Thyroid  Panbude et al.\nJournal of Gastrointestinal and Abdominal Radiology ISGAR   Vol. 2   No. 1/2019\nin a referral cancer center. This case highlights the challenge \nof confidently diagnosing deep pelvic endometriosis in an \nasymptomatic 41-year-old multiparous woman who was \npreviously treated for both  papillary thyroid cancer (PTC) \nand abdominal tuberculosis. Well-differentiated papillary \ncarcinomas of the thyroid in patients younger than 55 years, \nwith absence of nodal or systemic metastasis, lymphovas -\ncular invasion, extrathyroid spread, and small size (< 5 cm), \nare considered low risk. These rarely metastasize to distant \norgans, and this fact should be kept in mind, particularly \nwhen the thyroglobulin is within normal limits. The differ -\nential diagnoses for periureteral pelvic peritoneal lesions has \nbeen  discussed, and the imaging features of deep pelvic endo-\nmetriosis has been described. Endometriosis should always \nbe  included in the differential diagnosis of a pelvic mass in \n women of childbearing age group.\nConflict of Interest\nNone declared.\nReferences\n1  National Cancer Institute. Surveillance Epidemiology and End \nResults Data 1983 to 2009\n2  Cotran RD, Kumar VCT. Robbins Pathological Basis of Disease. \n6th ed. Philadelphia, PA: WB Saunders; 1999:1143–1144\n3  McCaffrey TV, Bergstralh EJHI, Hay ID. 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