A neonate presents with branchial cyst at the anterior border of the sternocleidomastoid muscle at the junction of the upper and middle thirds. This cyst is derived from which pharyngeal pouch/cleft and what epithelium lines it?

• A Second pharyngeal pouch (endodermal); lined by ciliated columnar epithelium
• B Third pharyngeal pouch (endodermal); lined by transitional epithelium
• C First pharyngeal cleft (ectodermal); lined by respiratory epithelium forming the external auditory meatus
• D Second pharyngeal cleft (ectodermal); lined by stratified squamous epithelium with lymphoid tissue ✓

Explanation

The second branchial (pharyngeal) cleft normally obliterates, but failure of obliteration results in a second branchial cyst (most common type) at the anterior border of SCM at the junction of upper and middle thirds. Being derived from the ectoderm of the second pharyngeal cleft, it is lined by stratified squamous epithelium and often contains lymphoid tissue because it may incorporate elements of the cervical sinus (confluence of 2nd, 3rd, and 4th clefts). Sinus tracts open externally at the SCM anterior border. The first pharyngeal cleft forms the external auditory meatus.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.