Congenital Cysts Enteric duplication cyst- An Often-Overlook
An enteric duplication cyst is a type of congenital choristoma, defined as normal tissue located in an abnormal location. Pathologically, enteric duplication cyst is defined by an epithelial lining that consists of histologically normal enteric mucosa as well as a smooth muscle covering, with an attachment to a portion of the alimentary tract . Although the pathophysiologic origin of enteric duplication cysts is heavily debated, they are thought to arise from an endodermal migration abnormality within the embryo. The majority of enteric duplication cysts occur within the small bowel, with enteric duplication cysts of the tongue considered a rare entity.

However, when enteric duplication cysts do occur in the head and neck, the tongue is the most common site of involvement. It is usually located in the ventral aspect of the oral tongue and extends into the floor of mouth. Radiologically, enteric duplication cysts are typically well-circumscribed and unilocular. When the enteric duplication cyst is large, it can be diagnosed prenatally via ultrasound, which may reveal an anechoic lesion without internal Doppler flow. Cross-sectional imaging better defines the overall extent of the enteric duplication cyst within the tongue and oral cavity, and is particularly helpful for preoperative planning, with MRI preferred because of its excellent soft-tissue contrast resolution. Both prenatal ultrasound and MRI can enable the radiologist to collaborate with the surgeon to predict whether there is potential for airway compromise after delivery according to the size, extent, and location of the cyst .

Like other cystic lesions, enteric duplication cysts of the tongue are usually hyperintense on T2-weighted MRI and nonenhancing. The T1-weighted signal intensity of such cysts is more variable, and hyperintensity suggests a high protein content. The differential diagnosis includes lymphatic malformation and dermoid cyst. Dermoid cysts may contain lipids or macroscopic fat or both, and therefore a fat-suppressed T1-weighted sequence can be helpful for the diagnosis of a dermoid cyst, distinguishing it from an enteric duplication cyst.