Branchial Cleft Cyst: This is the most common congenital neck cyst, typically presenting as a smooth, firm, and painless mass along the anterior border of the sternocleidomastoid muscle. It is a developmental anomaly that arises from the remnants of the branchial clefts.

Thyroglossal Duct Cyst: A congenital anomaly that occurs due to the failure of the thyroglossal duct to close during embryonic development. It usually presents as a midline neck mass that moves with swallowing.
Dermoid Cyst: A type of teratoma that can occur in the neck, containing elements from all three germ layers. It is typically a firm, painless mass.
Lymphatic Malformation (Lymphangioma): Although more commonly seen in children, it can present at any age as a soft, translucent, and sometimes fluctuant neck mass.

Metastatic Squamous Cell Carcinoma in a Lymph Node: Although less common as a primary presentation for a neck cyst, it is crucial to consider in the differential diagnosis, especially in adults with a history of smoking or other risk factors for head and neck cancer.
Tuberculous Lymphadenitis: Can present as a cystic neck mass, particularly in individuals from endemic areas or with immunocompromised status.
Carotid Body Tumor: A rare tumor of the carotid body that can present as a painless neck mass, usually at the bifurcation of the carotid artery.

Plunging Ranula: A type of mucous cyst that originates from the floor of the mouth and extends into the neck, presenting as a neck mass.
Cystic Hygroma: A lymphatic malformation that can occur in the neck, more commonly diagnosed in infancy or early childhood.
Teratoma: A tumor containing several different types of tissues, which can rarely present as a cystic neck mass.
Thymic Cyst: A rare congenital anomaly that can present as a neck mass, usually in the anterior superior mediastinum.