Substernocleidomastoid Muscle Neck Lipoma: An Isolated Case Report.

Introduction: We report this large neck mass, located behind the sternocleidomastoid (SCM) within the posterior cervical space and anterior to the prevertebral fascia. The mass is displacing the carotid sheath and its neurovascular contents medially. It extends almost the whole length of the SCM muscle all the way down to the lung apex.