Lymphoepithelial Cyst Presenting as a Lateral Neck Mass: A Diagnostic Pitfall in Adults.

Cystic lateral neck masses in adults are most commonly attributed to branchial cleft cysts. Lateral cervical lymphoepithelial cyst is a rare benign entity that may represent a diagnostic challenge because of its nonspecific clinical presentation. We report the case of a 32-year-old woman presenting with a slowly enlarging right lateral cervical swelling evolving for one year. Clinical examination revealed a painless, well-defined, and mobile mass. Cervical ultrasonography followed by CT demonstrated a well-circumscribed cystic lesion measuring 37 × 45 × 65 mm, initially suggestive of a branchial cleft cyst. Complete surgical excision was performed, and histopathological examination confirmed the diagnosis of a lymphoepithelial cyst. HIV serology was negative. The postoperative course was uneventful with no recurrence. This case highlights the diagnostic challenges of cystic neck masses in adults and emphasizes the importance of histopathological confirmation and surgical excision for definitive diagnosis and management.