Variable relationship of retro-mandibular vein to the facial nerve, a finding during parotid surgery: a rare case report

Studies describing the anatomical relation and variability of facial nerve and retro-mandibular vein were mostly on cadavers. Intraoperative encounter of variable anatomy in parotid surgery is rarely reported in literature. The usual location of retro-mandibular vein is medial to facial nerve as described in many classical text books is around 88%. Here we present a case with variable anatomy of retromandibular vein. A 55-year-old Indian gentleman presented with history of painless swelling in left parotid region for 5 months. On clinical examination, a 3×3 cm swelling probably arising from left parotid gland was felt. Preoperative ultrasonography described it as parotid cyst arising from inferior pole. Fine needle aspiration cytology described it as benign parotid cyst. A superficial parotidectomy was planned and executed. During surgery, the retro-mandibular vein was found crossing the two trunks of the facial nerve laterally (superficial to facial nerve) in between the division of facial nerve trunk and origin of ramifications. Usually retro-mandibular vein runs medial (deep) to the facial nerve trunks. Anatomical variations between facial nerve and retro-mandibular vein are underreported and not given due importance during training. With this article, we want to emphasize the importance of having awareness regarding anatomical variations related to facial nerve and retro-mandibular vein and be prepared to encounter during surgery there by preventing complications. We are reporting the first case from India.