Gut signature sign in enteric duplication cysts Eduardo Kaiser Ururahy Nunes Fonseca , Yoshino Tamaki Sameshima Diagnostic Imaging Department, Hospital Israelita Albert Einstein, Av. Albert Einstein, 627, Sa˜o Paulo 05652-901, Brazil Enteric duplication cysts, rare congenital anomalies that can appear at any point in the gastrointestinal tract, have a broad differential diagnosis. They are thought to result from an abnormal recanalization of the intestine during embryonic development, and more frequently affect the ileum [1, 2]. These cystic masses often are assessed by ultra- sonography. Sonograms facilitate lesion characterization by depicting a parietal stratification pattern similar to that of the normal intestine—a characteristic appearance known as ‘‘gut signature.’’ It refers to a hyperechoic in- ner layer, representing the mucosa, surrounded by a hypoechoic external layer, representing the muscular layer (Figs. 1, 2)[1, 2]. Although the gut signature sign is considered rela- tively specific for enteric duplication cysts, these lesions do not always have this classic appearance. Cysts of other origin, such as ovarian, Meckel diverticulum, or mesenteric also can present a layered wall that could simulate this sign [1]. Correspondence to: Eduardo Kaiser Ururahy Nunes Fonseca; email: edukaiser_unf@hotmail.com Fig. 1. Abdominal ultrasonographic image shows a cystic lesion in neonate. A The cyst wall presents a hyperechogenic inner layer (orange area in the magnified image—B) and a hypoechogenic outer layer (blue area the magnified image—B) representing, respectively, the mucosal and the muscular layer, characterizing the gut signature sign in an enteric duplication cyst. ª Springer Science+Business Media, LLC, part of Springer Nature 2018 Abdominal Radiology Abdom Radiol (2018) https://doi.org/10.1007/s00261-018-1620-2