{"paper_id":"fdfaad7c-9a16-4e8e-9b92-4765a7ca3f8c","body_text":"Abstract\nObjectives\nTo investigate if the shading sign is an exclusive MRI feature of endometriomas or endometrioid tumors, and to analyze its different patterns.\nMethods\nThree hundred and fourty six women with adnexal masses who underwent 1.5/3-T MRI were included in this retrospective, board-approved study. The shading sign was found in 56 patients, but five cases were excluded due to lack of imaging follow-up or histological correlation. The final sample included 51 women. The type of tumor and the pattern of shading were recorded for each case.\nResults\nThirty endometriomas and five endometrioid carcinomas were found. The remaining 16 cases corresponded to other benign and malignant tumors. The overall sensitivity, specificity, positive predictive value, and negative predictive value were 73%, 93%, 59%, and 96%, respectively. Restricting the analysis to cystic lesions without solid or fat component, sensitivity, specificity, positive predictive value, and negative predictive value were 73%, 96%, 94%, and 80%. Five shading patterns were identified: layering (15.7%), liquid–liquid level (11.8%), homogenous (45.1%), heterogeneous (11.8%), and focal/multifocal shading within a complex mass (19.6%). No significant correlation was found between these patterns and the type of tumor.\nConclusions\nThe shading sign is not exclusive of endometriomas or endometrioid tumors. Homogenous shading was the most prevalent pattern in endometriomas and half of the cases with focal/multifocal shading within a complex mass were endometrioid carcinomas.\nSimilar content being viewed by others\nReferences\nGlastonbury CM (2002) The shading sign. Radiology 224(1):199–201\nSiegelman ES, Outwater EK (1999) Tissue characterization in the female pelvis by means of MR imaging. Radiology 212(1):5–18\nGomori JM, Grossman RI, Hackney DB, et al. (1987) Variable appearances of subacute intracranial hematomas on high-field spin-echo MR. AJNR 8:1019–1026\nNishimura K, Togashi K, Itoh K, et al. (1987) Endometrial cysts of the ovary: MR imaging. Radiology 162(2):315–318\nTogashi K, Nishimura K, Kimura I, et al. (1991) Endometrial cysts: diagnosis with MR imaging. Radiology 180(1):73–78\nOutwater E, Schiebler ML, Owen RS, Schnall MD (1993) Characterization of hemorrhagic adnexal lesions with MR imaging: blinded reader study. Radiology 186(2):489–494\nCorwin MT, Gerscovich EO, Lamba R, Wilson M, McGahan JP (2014) Differentiation of ovarian endometriomas from hemorrhagic cysts at MR imaging: utility of the T2 dark spot sign. Radiology 271(1):126–132\nScarfone G, Bergamini A, Noli S, et al. (2014) Characteristics of clear cell ovarian cancer arising from endometriosis: a two center cohort study. Gynecol Oncol 133:480–484\nTanaka YO, Yoshizako T, Nishida M, et al. (2000) Ovarian carcinoma in patients with endometriosis: MR imaging findings. AJR 175:1423–1430\nKoshiyama M, Matsumura N, Konishi I (2014) Recent concepts of ovarian carcinogenesis: Type I and Type II. Biomed Res Int 2014:934261\nTerada T (2012) Endometrioid adenocarcinoma of the ovary arising in atypical endometriosis. Int J Clin Exp Pathol 5(9):924–927\nKurman RJ (2014) WHO Classification of Tumours of Female Reproductive Organs, vol. 6, 4th edn. Lyon: IARC\nPrat J (2012) New insights into ovarian cancer pathology. Ann Oncol 23(Supplement 10):x111–x117\nAuthor information\nAuthors and Affiliations\nCorresponding author\nRights and permissions\nAbout this article\nCite this article\nLopes Dias, J., Veloso Gomes, F., Lucas, R. et al. The shading sign: is it exclusive of endometriomas?. Abdom Imaging 40, 2566–2572 (2015). https://doi.org/10.1007/s00261-015-0465-1\nPublished:\nIssue date:\nDOI: https://doi.org/10.1007/s00261-015-0465-1","source_license":"CC0","license_restricted":false}