SECTION EDITOR: C. DOUGLAS PHILLIPS, MD
Intramuscular hemangiomas are rare, benign neoplasms that represent fewer than 1% of all benign vascular neoplasms.1 They most often develop in the trunk and extremities; however, 10% to 20% occur in the head and neck, with the masseter muscle being the most common site.2,3 Most intramuscular hemangiomas occur with similar incidence between men and women, although those that involve the masseter muscle arise more frequently in men.1 Hemangiomas frequently present within the first 3 decades of life, suggesting a congenital correlation. Congenital vascular malformations are thought to evolve from an abnormally differentiated endothelial primordial network and grow along the planes of least resistance, explaining their locally invasive nature.4 Repeated trauma to the muscle, reported in 20% of cases, as well as hormonal influences such as oral contraception, has also been proposed as a possible cause.4,5 Histologically, the tumors are characterized as capillary/small vessel or cavernous/large vessel. Small-vessel hemangiomas measure less than 140 mm in diameter, account for 50% of intramuscular hemangiomas, and most frequently occur in the head and neck region. Large-vessel hemangiomas measure more than 140 mm in diameter, are seen most commonly in the trunk and extremities, usually have a longer duration of symptoms, and tend to be larger and more painful. Hemangiomas may also be classified as mixed type.1,5,6
Radiology Quiz Case 1: Diagnosis. Arch Otolaryngol Head Neck Surg. 2012;138(12):1186. doi:10.1001/archotol.138.12.1186
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