Lingual Foregut Duplication in a Middle-Aged Adult

Discussion

Embryologically, the primitive foregut gives rise to the pharynx, the respiratory tract, the esophagus, the stomach, and the duodenum to the level of the ampulla of Vater. There is no single theory that fully explains the embryogenesis of foregut duplications, but notochordal abnormalities appear to have a role.⁶ Lingual duplications may alternately reflect abnormal cellular migration because the primitive foregut and the pharyngeal arches (containing the developing tongue) are in close proximity.² Foregut duplications are considered choristomas, with a wide range of ectopic tissues. In a prior review of 52 pediatric oral cavity choristomas, gastrointestinal epithelium lined most cysts, and the anterior two-thirds of the tongue was most frequently affected.²

The clinical presentation of any foregut duplication cyst is a reflection of its location, its mass effect, and complications of the ectopic mucosal lining.⁶ Oral cavity duplication cysts are usually asymptomatic, but there is a potential for respiratory and/or feeding problems in the infant. While mass effect is a common presentation in younger patients, degeneration into malignancy is a possible outcome in the adult, indicating that early surgical removal is preferred.⁷ The clinical differential diagnosis of a mass in the anterior tongue includes dermoid cyst, hamartoma, neurofibroma, teratoma, lymphoepithelial cyst, squamous cell carcinoma, and glandular neoplasms. Although radiologic findings usually cannot provide a definitive diagnosis, imaging has an important role in the evaluation of these patients, both for narrowing the differential diagnosis and for surgical planning. Complete excision of the cyst is the treatment of choice for foregut duplications, with no recurrences reported.⁸

MR imaging is the technique of choice for oral cavity lesions, providing excellent contrast resolution of soft tissues with multiple pulse sequences, but enhanced CT may also be useful in the absence of dental amalgam. Lingual duplications typically appear as nonenhancing or thinly rim-enhancing cystic lesions. On T1-weighted images, they may be of variable intensity, depending on the proteinaceous content. On T2-weighted images, they appear uniformly hyperintense.⁸ CT typically reveals a well-defined homogeneous cystic mass, but loculation is possible.⁹ Prenatally, sonography can also be of diagnostic use, followed by MR imaging for confirmation.¹

The radiologic differential diagnosis of a cystic anterior tongue mass includes dermoid cyst, venolymphatic malformation, and foregut duplication cyst. Because dermoid cysts have various skin elements in their epithelial lining, they appear on CT as cystlike masses with variable (or even mixed) densities. On MR imaging, they appear as nonenhancing cystic lesions, which may have increased T1 signal intensity from fat content. The presence of proteinaceous fluid in duplication cysts produces similar signal intensities on T1 and T2 sequences, so these lesions may be difficult to distinguish.⁸ Mucocele of the tongue demonstrates the typical findings of a cystic lesion, with low signal intensity on T1 and high signal intensity on T2.¹⁰ Venolymphatic malformations display similar signal intensities on T1 and T2 sequences, with a heterogeneous and often infiltrative appearance.^11,12 Thus, differentiating among these various lesions radiographically can be problematic, and excisional biopsy is needed for the final diagnosis.

In summary, lingual duplication cysts are uncommon in the pediatric population, and the diagnosis is exceedingly rare in adults. Nevertheless, this diagnosis must be considered even in middle-aged patients presenting with an anterior tongue mass.