Deep Extension from Carcinoma Arising from the Gingiva: CT and MR Imaging Features
Yasuo Kimuraa,
Misa Sumia,
Tadateru Sumia,
Yoshiko Arijib,
Eiichiro Arijib and
Takashi Nakamuraa
a Department of Radiology and Cancer Biology, Nagasaki University School of Dentistry
b Department of Oral and Maxillofacial Radiology, Aichi-Gakuin University, School of Dentistry
View larger version (145K):
[in a new window]
|
FIG 1. Axial T1-weighted MR image in a 69-year-old woman with lower gingival cancer in the right molar region shows cancer (arrows), which is spreading into the buccal and sublingual spaces (*). The sublingual space is superomedial to the mylohyoid muscle (m). The genioglossus muscle (g) borders the space medially, and the lingual aspect of the mandible borders it anteriorly and laterally. The tumor spreads posteriorly into the retromolar trigone and contiguously from the buccal space.
| |
View larger version (108K):
[in a new window]
|
FIG 2. Axial CT scan in a 72-year-old woman with lower gingival cancer in the left molar region shows that cancer involves the infratemporal and temporal portions of masticator space. The tumor extends into the parotid gland (p) and the deep belly of the temporalis muscle (t).
| |
View larger version (108K):
[in a new window]
|
FIG 3. Axial gadolinium-enhanced T1-weighted MR image in a 45-year-old man with upper gingival cancer in the right molar region shows cancer (arrows), which is spreading into the buccal space but not the masticator space. Note that a thin fat layer (arrowheads) is present between the cancer and mandibular ramus.
| |
View larger version (58K):
[in a new window]
|
FIG 4. Extension pathways of lower gingival cancer.
A, Diagram shows the pathways for the spread of lower gingival cancers in molar region into the buccal, masticator, and sublingual spaces. The retromolar triangle or buccal space immediately anterior to mandibular ramus serves as a corridor for cancers to spread into the masticator space. Note that a fat space exists between the medial pterygoid muscle and mandibular ramus; this is a site at which cancer can spread from the retromolar triangle without substantial bone destruction. In contrast, cancers that spread into the buccal space, after tunnelling through the alveolar ridge and then bypassing the buccinator muscle attachment, may destroy the anterior portion of mandibular ramus and invade the masticator space.
B, Photograph shows the topological relationship of lower gingival cancers that spread into masticator space and the muscle attachments to mandible. Colored areas indicate muscle attachments to the mandible: red indicates the buccinator; black, temporalis; green, medial pterygoid; and blue, mylohyoid. Arrows indicate two pathways for lower gingival cancer spread into the masticator space.
| |
