Venous malformation of the sternomastoid muscle: A case report and review

Abstract

Objectives: Intramuscular venous malformations occur rarely in the head and neck. Only 11 cases involving the sternomastoid muscle have been reported. Methods: We present a case involving a 12-year-old female. We review the literature and discuss diagnostic and therapeutic aspects of this unusual entity. Results: Definitive evaluation of venous malformations of the head and neck skeletal muscles is best accomplished with T1- and T2-weighted magnetic resonance imaging coupled with the clinical history and physical exam. Complete surgical excision is recommended and is usually curative, with little morbidity. Our patient first presented at the age of 4 with a nontender neck swelling within the sternomastoid muscle. The mass had enlarged dramatically by age 12, thereby necessitating surgical excision. Fine needle aspiration yielded gross blood. The mass was hyperintense on a T2-weighted magnetic resonance image consistent with a vascular malformation. Transcervical surgical excision was performed, dissecting the mass from feeding vessels within an envelope of attenuated sternomastoid muscle, preserving the spinal accessory nerve. Histologic evaluation revealed medium-sized and thin-walled channels that were lined with a flattened endothelial layer and surrounded by a poorly developed and variably evident smooth muscle sheath, consistent with a venous malformation. She is doing well now 4 months after surgery without signs of recurrence or functional compromise. Conclusion: Venous malformations of skeletal muscle are frequently labeled as intramuscular hemangiomas. These are more accurately called intramuscular venous malformations based on clinical imaging and pathologic criteria. We add the twelfth case of a venous malformation of the sternomastoid muscle to the literature.