Accessory cervical thymic tissue has been rarely reported. However, it should be included in the differential diagnosis of neck masses in children, along with branchial anomalies, lymph nodes and other tumors. This lesion occurs along the descending line of the thymus between the angle of mandible and superior mediastinum. A 2-month-old infant presented with an asymptomatic left sided neck mass. MRI revealed a well defined homogeneous mass in the deep lobe of left parotid gland. At operation, an easily identified soft tissue mass was found in the left submandibular area, measuring 3 × 1.5 cm. It was completely excised. Microscopic examination revealed normal thymic tissue.

Thymolipoma is a rare benign mediastinal tumor, composed of mature fatty and thymic tissues. A 9-year-old boy was referred with a one-month history of neck swelling. Preoperative computed tomography scan and fine needle aspiration biopsy suggested thymolipoma. Despite it being rare, thymolipoma should be considered in the differential diagnosis of mediastinal tumors. Characteristics of its clinical feature and radiological findings that can differentiated it from other mediastinal tumors are discussed with a review of the literatures.

Aberrant migration of thymic tissue occurs as an ectopic thymus in the mediastinum, base of skull, tracheal bifurcation, and cervical region. A recent review of the literature by Nowak et al. showed over 70 reported cases of aberrant thymus or thymic cyst in patients who presented with primary neck masses. Authors experienced a case of ectopic cervical thymus and reviewed the literature. A one-year-old boy with left neck swelling which had been noticed since one month of age visited out patient clinic. Ultrasonography showed a well-defined cystic mass containing homogeneous, low-echogenic content locating in the lateral aspect of the left carotid sheath. Operation was performed under the impression of branchial cleft cyst. At surgery, a multiseptated, well-encapsulated, brownish and doughy mass which was extending into the vicinity of the carotid bifurcation with sland stalk-like portion ending between the hypoglossal nerve and external carotid artery was excised completely. The cut-surface showed homogenous solid mass, and on frozen section the tissue revealed a normal thymic histology. Postoperative ultrasonography showed bilateral thymus in the superior mediastinum. The patient has no immunologic problem and is doing well now.