A bump in the neck. Myositis ossificans of the omohyoid muscle: Imaging findings.

Myositis ossificans is a benign ossifying soft-tissue mass that occurs in muscle. In the majority of cases it is related to trauma but rarely observed in the neck. A 54 year-old-man with history of minor trauma and anticoagulant drug assumption for V Leiden mutation, was referred to our institution for a painless mass in the right supraclavicular fossa. On CT plan study a mass with negative attenuation values located in the posterior triangle of the neck, into the inferior belly of the right omohyoid muscle was evident. On MRI the lesion appears as an ovalar mass, with smooth borders, isointense to muscles on T1 images, isointense to fat on T2 images, intensely enhancing after i.v. Gd administration. After surgical removal the pathologist concluded for the nature of myositis ossificans. This is the first case, as far as we know, reported in the literature of a myositis ossificans arising in the inferior belly of the omohyoid muscle in a patient treated with dicumarol.