A case of cervical thymic cyst is reported, and the Japanese literature is reviewed in this paper. A 12-year-old-boy presented with a painless left neck mass (5 x 4 cm). The preoperative diagnosis was cystic disease of the neck, based on ultrasound examination, CT and MRI study. At surgery, a cyst adhering to the vagus nerve was extirpated from both the carotid artery and the jugular vein, which were connected to the mediastinum. The pathological diagnosis was multilocular thymic cyst, which showed normal thymic tissue, in addition to granulation with areas of chronic inflammation and fibrosis with cholesterol clefts and Hassall's corpuscles in the cystic wall.
Twenty-eight cases of cervical thymic cyst in the Japanese literature are reviewed and discussed briefly. The mean age of the patients was 31 years. Sixteen cervical thymic cysts (57%) occurred on the left side of the neck. Painless neck swelling was noticed in all except 3 patients. Seven cervical thymic cysts (32%) had mediastinal connections. Some cysts included foci of thyroid tissue (one patient) and parathyroid tissue (3 patients). Due to their rare occurrence, cervical thymic cysts can be misdiagnosed as other cystic lesions of the neck. Cervical thymic cysts should be taken into account in the differential diagnosis of neck masses.
