Читать книгу Salivary Gland Pathology - Группа авторов - Страница 82

The sublingual gland (SLG) is the smallest of the major salivary glands and is the least likely to be involved with pathology. The SLG measures an approximately 3.5 cm in oblique AP, 1.0 cm in oblique LR, and 1.5 cm in SI dimensions. Anatomically, the SLGs exist in the floor of mouth and lie on the superior surface of the mylohyoid muscle, bordered anteriorly and laterally by the mandible, and medially by the submandibular duct, genioglossus muscle, and geniohyoid muscle. The submandibular gland serves as its posterior border (Figures 2.44 through 2.46 ). The sublingual gland communicates with the oral cavity via multiple small ducts (ducts of Rivinus) opening into the floor of mouth adjacent to the sublingual papilla. These small ducts may be fused and form a larger single duct (duct of Bartholin) and empty into the submandibular duct (Beale and Madani 2006).

Figure 2.44. Axial CT of the neck at the level of the sublingual gland demonstrating mild normal enhancement along the lateral floor of mouth.

Figure 2.45. Axial contrast‐enhanced T1 MRI of the sublingual gland demonstrating enhancement (a). Note the deep lobe of the submandibular glands seen at the posterior margin of the sublingual glands. Coronal T2 weighted image demonstrating the sublingual gland “cradled” between the mandible laterally, the genioglossus muscle medially, the geniohyoid muscle inferomedially, and the combined mylohyoid and digastric muscles inferiorly (b).

Figure 2.46. Axial PET of the sublingual gland demonstrating the intense uptake seen in the sublingual glands bilaterally medial to the mandible (photopenic linear regions).

The SLG can be seen by CT and MRI and is similar in appearance to the SMG, although smaller (Sumi et al. 1999a). FDG uptake is less well defined since it is small and closely approximated to adjacent skeletal muscle, but the uptake is moderate.

Occasionally, accessory salivary tissue is found in the SMS along the anterior aspect (anterior to the normal submandibular gland). This is caused by herniation of sublingual gland through defects in the mylohyoid muscle, called a mylohyoid boutonniere, which typically occurs between the anterior and posterior parts of the mylohyoid muscle. The accessory gland may be accompanied by sublingual branches of the facial artery and vein. Although the accessory tissue may mimic a tumor, this should be readily identified as normal since the accessory tissue has the same characteristics on CT and MRI as normal sublingual or submandibular gland (White et al. 2001; Hopp et al. 2004).