51 Hellenic Journal of Surgery 2013; 85: 2 Abstract An 11-year old boy presented with a painless mass in the left side of the posterior cervical triangle and reported dyspnoea during physical exercise. Total surgical resection and histological examination of the mass confirmed the diagnosis of a cervical thymic cyst. With just few reported cases, cervical thymic cysts represent a rare entity. They usually present as painless masses. The clinical symptoms, differential diagnosis and therapeutic approach are discussed herein. Key words: Cervical mass, Τhymic cyst, Βrachial cyst Introduction Cervical masses are not uncommon in the paediat- ric population; they are usually caused by thyroglos- sal duct cysts, brachial cleft cysts and cystic lymp- hangiomas[1]. However, a cervical thymic cyst is a rare finding. Typically congenital, this cyst mostly presents on the left side of the neck (68%)[1]. We present the case of a child diagnosed with a cervical thymic cyst, and discuss the clinical symptoms, differen- tial diagnosis, and management of this rare pathology. Case report Written informed consent has been obtained from the parents of the patient, for the publication of his personal data. An 11-year-old boy presented to our department with a painless mass in the left side of the posterior cervi- cal triangle which had begun to manifest six months earlier. The mass became more evident on Valsalva P. G. Voskou (Corresponding author) - Department of Neurology, Aghia Sophia Children’s Hospital, Athens, Greece S. Antypas - Department of Surgery, Aghia Sophia Children’s Hospital, Ath- ens, Greece A. Kourtesis - Department of Cardiothoracic Surgery, Aghia Sophia Children’s Hospital, Athens, Greece e-mail: p.voskou@yahoo.gr manoeuvre. Other than dyspnoea during physical exercise, the patient had not experienced any pain, dysphagia, hoarseness of voice, cough or fever. An ultrasound examination revealed a single unloculat- ed cystic mass extending from the mandibular angle to the sternum, suggestive of a cystic lymphangioma (Fig. 1). Chest radiography displayed a mass extend- ing to the superior anterior mediastinum. Magnetic resonance (MRI) imaging identified an ovoid struc- ture located in the posterior border of the sterno- cleidomastoid muscle with moderately high signals on T1 and T2 weighted images; no amplification was observed after administration of a magnetic contrast agent, and adjacent tissues presented with normal signal intensity (Fig. 2). These findings indicated a possible diagnosis of brachial cleft cyst. Surgical in- tervention with a left side transverse cervical incision opening up the platysma muscles revealed a mass measuring 15 cm x 6 cm that extended to the carotid sheath, displacing its components to the median and anterior of the anatomical plane. The surgical border of the mass was identified intraoperatively and sepa- rated from the contents of the carotid sheath, i.e. the internal jugular vein, common carotid artery, vagus nerve and lymph nodes. A complete resection of the mass was performed without the need for thoracotomy. Thymic Cyst Presented as a Painless Cervical Mass in a Child P. G. Voskou, S. Antypas, A. Kourtesis Received 14/11/2012 Accepted 14/12/2012 Case Report Fig.1 Ultrasound examination revealed the cystic mass located- between the internal jugular vein (IJV) and the common carotid artery(carotid). 113