Anomalous Posterior Branching of the Internal Jugular Vein: A Report of Two Patients.

The internal jugular vein (IJV) is an important vein encountered during most routine major head and neck surgeries. The IJV is known to infrequently present with anatomical variations, commonly duplication and fenestration. This report presents two cases that highlight an unusual anatomical variation of the IJV, namely the posterior tributary, which was encountered during neck dissection for papillary carcinoma of the thyroid and metastatic cervical lymph nodes. The first case was a 50-year-old woman with papillary carcinoma of the thyroid and regional metastasis, who underwent extensive neck dissection. During dissection, an anomalous posterior tributary of the IJV was discovered, originating around 3 cm above the omohyoid tendon-IJV junction. In case 2, a 40-year-old woman with a history of thyroidectomy exhibited a similar anomaly during neck dissection. In both cases, the posterior tributary was observed branching into two divisions. These cases emphasize the significance of recognizing anatomical variations to avoid inadvertent damage during surgical procedures. Anomalies like the posterior IJV tributary could have implications for surgical planning, emphasizing the importance of thorough exploration and understanding of individual variations. Awareness of such variations will help facilitate surgeons in safely performing neck dissections.