Cervical Thymic Cyst - An Overlooked Entity

Thymic cysts are one of the rare causes of neck masses in the paediatric age group. Patients may complain of neck swelling either central or lateral neck swelling. There is difficulty in diagnosing a cervical thymic cyst as it may mimic a branchial cleft cyst or a cervical lymphangioma. Definitive diagnosis of a thymic cyst requires histopathological examination of thymic tissue. We report a case of a 6-year-old girl who presented with painless lateral neck swelling for 2 months duration. Computed tomography (CT) scan showed a left branchial cyst with retropharyngeal extension. The patient underwent complete excision of the mass and histological examination was reported as a cervical thymic cyst. Postoperatively, she was able to be discharged after serial follow-ups with no signs and symptoms of recurrence.