Fusiform Cervical Mass in a 6-Year Old Boy; Do not Forget the Thymic Cyst

Cervical thymic cyst is a rare clinical entity, with approximately one hundred cases reported in the literature so far. The purpose of this case report is to highlight some certain features, along with an extensive research of the relevant literature. A 6-year-old boy was admitted to the Otorhinolaryngology Department due to the presence of a left-sided, painless, latero-cervical swelling, first observed by his parents 2 weeks ago. Physical examination revealed a painless, well-delineated mass, with no signs of inflammation. No enlarged cervical nodes were present. The mass extended from the mandibular angle, under the sternocleidomastoid muscle, in proximity with the ipsilateral neurovascular bundle. Ultrasound transverse gray-scale panoramic view detected a wellcircumscribed lesion, with fine echogenic foci, appearing in close proximity with the upper pole of the left thyroid lobe and the ipsilateral common carotid artery. Elective surgical intervention with complete mass excision was performed. Histopathological examination confirmed the diagnosis of a cervical thymic cyst. Cervical thymic remnants represent a group of neck masses that pediatricians and pediatric surgeons should consider in differential diagnosis of both cystic and solid neck masses. Most cystic cervical thymic masses are found in the lower third of the anterior neck, extending deep to the sternocleidomastoid muscle, featuring close anatomic relationship with the composites of the ipsilateral carotid sheath. Elective surgery is kept as the treatment of choice, after ruling out the possibility of subject immunologic disturbance.