Cervical thymic cysts

Rare case of cervical thymic cyst diagnosed on pre‐operative imaging

“…While malignant degeneration has not been documented in a CTC, it has been documented in mediastinal thymic cysts and in ectopic thymic tissue . Pre‐operative diagnosis as occurred in our case has been reported but is extremely rare . For diagnostic and therapeutic reasons, excision is generally recommended as definitive diagnosis is histological .…”

“…CTCs are a rare phenomenon thought to account for less than 1% of neck masses . The majority of patients are male in the first decade of life, though presentation can be into young adulthood; 70% occur on the left side of the neck …”

“…Thymic tissue develops from the third branchial arch which elongates and is severed from the pharynx during the seventh foetal week. Descent into the mediastinum occurs during the eighth to ninth week and arrest of descent, sequestration of tissue or failure of evolution at any level can lead to cervical thymic tissue from the angle of the mandible to the mediastinum . The two primary explanations for cyst formation are the persistence of thymopharyngeal ducts and degeneration of Hassall's corpuscles within ectopic thymic remnants …”

“…CTCs are a rare phenomenon thought to account for less than 1% of neck masses. 2,3 The majority of patients are male in the first decade of life, though presentation can be into young adulthood; 4 70% occur on the left side of the neck. 1,5 Thymic tissue develops from the third branchial arch which elongates and is severed from the pharynx during the seventh foetal week.…”

“…Descent into the mediastinum occurs during the eighth to ninth week and arrest of descent, sequestration of tissue or failure of evolution at any level can lead to cervical thymic tissue from the angle of the mandible to the mediastinum. [1][2][3] The two primary explanations for cyst formation are the persistence of thymopharyngeal ducts and degeneration of Hassall's corpuscles within ectopic thymic remnants. 2 While they are generally asymptomatic at presentation, 6% present with compressive mechanical symptoms and there are rare cases of airway obstruction reported in infants.…”