{"paper_id":"a8843730-2cc5-42c8-a8bf-ad99c9878b81","body_text":"Tamoxifen, a drug that is widely used in the chemotherapeutic management of breast\ncancer because of its antiestrogenic action in the breast tissue, has also an agonist\neffect on the endometrium. In long-term therapies, this drug leads to endometrial\nproliferative disorders, including a wide spectrum of endometrial abnormalities such as\nendometrial hyperplasia, hyperplastic polyps and endometrial cancer, besides being\nassociated with endometriosis in postmenopausal patients ( 1 ) .\nIn the last years, many studies have been published about imaging diagnosis of\nendometriosis, highlighting particularly the role of transvaginal ultrasonography (US)\nand magnetic resonance imaging (MRI) as methods of choice. Such methods allow for an\nappropriate assessment of involved sites, as well as the surgical planning, as\nnecessary. In cases of dubious diagnosis, percutaneous biopsy represents a useful and\nless invasive alternative to confirm the diagnosis.\nIn the present case report, the authors highlight the value of pelvic MRI findings that\nhave led to the diagnostic suspicion of periureteral lesion in a postmenopausal patient\nundergoing tamoxifen therapy for breast cancer, who presented with left lumbar pain\nsecondary to hydronephrosis. The differential diagnosis of metastasis from breast cancer\ncould be ruled out and the diagnosis of endometriosis could be histopathologically\nconfirmed by means of multislice computed tomography (MCT)-guided percutaneous\nbiopsy.\n\nA 55-year-old female patient with previous history of breast cancer, undergoing\ntamoxifen therapy for two years, without any other comorbidity or history of surgery,\npresented with nonspecific left lumbar pain. She was submitted to US that demonstrated\nleft hydronephrosis, with no noticeable obstructive factor.\nComplementary MRI showed the presence of a solid retroperitoneal tissue with retractile\naspect involving the left ureter at the level of the intersection with the iliac\nvessels, causing ureteral stenosis and hydronephrosis ( Figure 1 ).\nMRI: axial T2-weighted  (a) , coronal  (b)  and T1-weighted\nimage with fat-suppression  (c)  revealing retroperitoneal solid,\nretractile tissue (arrows) with predominant low signal intensity on T1- and\nT2-weighted sequences, located in periureteral site at the level of the\nintersection with iliac vessels, determining ureteral obstruction and\nhydronephrosis  (d) .\nUreteroscopy demonstrated an intraluminal polypoid lesion whose biopsy results were\ncompatible with chronic inflammatory process. Considering the patient's history of\nbreast cancer, the possibility of metastatic involvement of the left ureter was\nconsidered, and MCT-guided percutaneous biopsy ( 2 )  ( Figure 2 ), with\nan 18-gauge needle was performed.\na:  Percutaneous biopsy of a left retroperitoneal periureteral\nretractile lesion (arrow).  b:  Anterior abdominal approach with\nextrinsic compression of the abdominal wall for bowel loops separation.\nThe histopathological result was compatible with endometriotic tissue ( Figure 3 ), so oncologic therapy was ruled out, and\nclinical treatment for deep pelvic endometriosis was initiated, considering a surgical\napproach with ureteral reimplant. As the patient was about to complete the therapy with\ntamoxifen, the use of this drug was discontinued in an attempt to allow regression and\nspontaneous volumetric reduction of the endometriotic tissue, which in fact has\noccurred. Two months later the patient became asymptomatic, with no significant\ncompromise of the renal filtration and excretion at  99m Tc-DTPA renography. Up\nto now an invasive approach has not been necessary . If the patient remained symptomatic\nor in case of renal function compromise, a surgical resection of the fibrotic tissue and\nof the affected ureteral segment would be needed, with ureteroureteral anastomosis or\nureterovesical bypass with a psoic bladder.\na:  Filiform fragment of fibroadipose tissue showing tubular glands\nintermingled with spindle cell stroma in one of the extremities (hematoxylin-eosin\nstaining, 100× magnification).  b:  Squamous and cylindrical glandular\nepithelium with no atypical finding (asterisk) intermingled with spindle cell\nstroma with foci of hemorrhage, both with appearance resembling endometrium\n(hematoxylin-eosin staining, 400× magnification).  c:  Cytological\npreparation performed during the biopsy specimen collection (in order to evaluate\nthe appropriateness of the specimen) showing a large cluster of epithelial cells\nwith no atypias (panoptic staining, 400× magnification).\n\nEndometriosis, defined as presence of endometrial tissue in extrauterine locations,\npossibly causing dysmenorrhea, dyspareunia, pelvic pain and infertility ( 3 ) , is an extremely rare entity in\npostmenopausal women.\nFrequent sites of endometriotic involvement include ovaries, uterine ligaments, serous\nsurfaces, Douglas cul-de-sac, uterine tubes, rectosigmoid, and the vesicouterine\nspace ( 3 , 4 ) . However, endometriotic implants may\naffect the urinary tract in up to 20% of cases, affecting, in decrescent order, bladder,\ndistal ureter, kidneys and urethra. Ureteral endometriosis rarely occurs, representing\nonly 0.08% to 1% of cases, particularly in premenopausal women ( 5 , 6 ) .\nSeveral unusual manifestations of endometriosis have been observed because of the\nincreasing utilization of diagnostic imaging methods such as US and principally MRI. The\nmultiplanar imaging capability and the high sensitivity of MRI to detect hematic\ncomponents, in association with the capability in identifying sites of endometriotic\ninvolvement hidden by gross adhesions, have made MRI the method of choice for the\ndiagnosis of endometriosis ( 4 , 7 , 8 ) , with sensitivity, specificity and\naccuracy of respectively 90-92%, 91-98% and 91-96% ( 9 ) .\nIn the present case, besides the rarity of endometriotic involvement in unusual sites\nand age range, what calls one's attention is the fact that the patient was under\ntamoxifen therapy. There is not sufficient reports in the literature to support the\nevidence that the use of tamoxifen can lead to the development of a previously\nnon-existent focus of endometriosis or whether it just exacerbates pre-existing\nendometriotic foci; but the occurrence of an estrogen-dependent disease in\npostmenopausal patients submitted to tamoxifen therapy suggests a close causal\nrelationship between the use of this drug and development of\nendometriosis ( 1 ) .\nIn the present case, the patient was a postmenopausal woman without previous history or\nsymptoms suggestive of endometriosis. Thus, it is not possible to rule out the\npossibility of development of a previously non-existent focus of endometriosis, or even\na clinical exacerbation of an, until then, asymptomatic disease secondary to the use of\ntamoxifen.\nGiven the relevance of imaging diagnosis of this disease, it is necessary that the\nradiologist recognizes and is attentive to MRI findings suggestive of this diagnosis,\nwith emphasis on the constant necessity of evaluation and correct clinical-radiological\nand pathological correlation aiming at the application of appropriate therapeutic\nmeasures.\nFinally, the present case report highlights the rare occurrence of endometriosis in an\nunusual site, in a postmenopausal woman undergoing tamoxifen therapy, whose diagnosis\nmight be suspected by MRI findings.","source_license":"CC0","license_restricted":false}