Accessory salivary tissue in the mylohyoid boutonniere: A clinical and radiologic pseudolesion of the oral cavity

BACKGROUND AND PURPOSE: Though classically depicted as a continuous muscula r barrier between the sublingual and submandibular spaces, the mylohyoid mu scle is often discontinuous. These areas of discontinuity may contain fat, blood vessels, salivary tissue, or combinations thereof that may be mistake n both clinically and radiologically for pathologic abnormalities. We sough t to demonstrate the prevalence and radiologic appearance of dehiscence of the mylohyoid muscle. METHODS: One hundred axial, contrast-enhanced CT studies of the neck, obtai ned over a 10-month period, were retrospectively reviewed. Inclusion criter ia included 3-mm-thick slices and absence of pathologic abnormalities or su rgical changes in the oral cavity, Scans mere assessed for the presence and contents of mylohyoid defects such as accessory salivary tissue, defined a s nonlymphoid tissue within defects in the mylohyoid, having attenuation an d enhancement characteristics similar to those of orthotopic sublingual and submandibular salivary tissue. RESULTS: Mylohyoid defects were identified in 77 of 100 individuals. The de ficiencies were bilateral in 67% and unilateral in 33%. Accessory salivary tissue was identified in 37 of 100, Fat and blood vessels were commonly ide ntified within the mylohyoid defects. Sixty-one percent of the defects cont ained only fat. Thirty-five percent of the defects contained blood vessels. CONCLUSION: Deficiencies in the mylohyoid muscle were visible in 77% of ind ividuals who underwent scanning, The defects may contain fat, blood vessels , salivary tissue, or all three characteristics. Accessory salivary tissue was identified in 37% of individuals who underwent scanning, Recognition of mylohyoid deficiencies and the typical appearance of accessory salivary ti ssue will allow accurate diagnosis of this benign, anatomic variant.