Management of a cervical thymic cyst in a child: Case report and diagnostic insights

Cervical thymic cysts are rare congenital lesions of the neck, accounting for around 0.3% of cervical cystic anomalies in the pediatric population. These lesions generally manifest in early childhood as painless, slowly enlarging masses in the neck. They are thought to develop along the natural route of thymic migration, which extends from the angle of the mandible down to the superior mediastinum. Owing to their location and clinical presentation, they are often mistaken for more commonly encountered neck masses such as branchial cleft cysts or lymphangiomas. When large enough, these cysts can compress nearby structures, potentially leading to symptoms like dysphagia, respiratory distress, or voice alterations. Surgical excision is the treatment of choice, and a definitive diagnosis is usually made based on histopathological findings after removal. This case report highlights a 7-year-old girl who presented with a non-tender swelling on the left side of her neck. Initial radiological assessments suggested a branchial cleft cyst or lymphangioma; however, the diagnosis of a cervical thymic cyst was established only after surgical excision and histological evaluation. The diagnostic approach and therapeutic management are detailed in this report.