Ectopic cervical thymic tissue - Diagnosis by fine needle aspiration

Cervical thymic masses are congenital lesions that result from aberrant thy mic migration during embryogenesis. Although most of these masses are asymp tomatic, they may cause debilitating symptoms secondary to encroachment on adjacent aerodigestive structures. Preoperative diagnosis of ectopic thymic tissue is rare; most cases are clinically misinterpreted as branchial clef t remnants or cystic hygromas. Definitive diagnosis has relied on histopath ologic examination in nearly all reported cases. However, the invasiveness of open incisional or excisional biopsy carries the risk of surgical and an esthetic complications. Inadvertent surgical thymectomy may result in cell- mediated immune deficiencies in infants and young children. The utility of fine needle aspiration is gaining wider acceptance in the diagnostic evalua tion of neck masses. We describe an infant with an asymptomatic cervical th ymic mass diagnosed by fine needle aspiration.