Atypical cervical ectopic thymus located in the submandibular space: a case report.

Ectopic thymic tissue is a rare finding and a rare cause of lateral neck masses. Here, we present a case of a 3-month-old male infant with a painless left sided submandibular mass. The case highlights the diagnostic power of ultrasound in differentiating ectopic thymic tissue from other pediatric neck masses, often rendering more expensive or invasive imaging unnecessary or potentially counterproductive and allowing to avoid unnecessary procedures and possible complications.