Figure 10b.  Second branchial cleft cyst in a 30-year-old woman with a 14-month history of a mass in the left side of the neck that was unresponsive to antibiotics and that enlarged somewhat the month before surgery. (a) Axial T1-weighted image shows a well-defined mass (m) along the anterior border of the left sternocleidomastoid muscle (arrowhead), lateral to the carotid space (white arrow), and posterior to the submandibular gland (black arrow)—the classic location for a second branchial cleft cyst. Increased signal intensity of the mass is due to either proteinaceous debris or prior hemorrhage. (b) Axial T2-weighted image reveals moderate to marked hypointensity of the mass (m), consistent with accumulation of proteinaceous debris or hemorrhage. (c) Coronal contrast-enhanced T1-weighted image with fat suppression shows mild rim enhancement of the mass (m). (d) Intraoperative photograph shows the mass and sternocleidomastoid muscle outlined in ink on the skin surface. (e) Photograph of the surgical specimen shows the well-circumscribed mass with mildly lobulated contours.