Patient History
Right jaw pain. Clinical exam noted a mass behind the right 3rd molar tooth.
Findings
Pre- and post-contrast MR was performed of the region of the oral cavity in a patient with right jaw pain. The study is abnormal. There is an aggressive lesion that measures approximately 2.5cm in largest dimension that involves the right retromolar trigone that appears to be centered posterior to the right mandible. The tumor extends posteriorly along the superior constrictor muscle along the pteryomandibular raphe to the expected insertion of the right palatoglossus muscle into the tongue base. Thus, there is involvement of the inferior portion of the right anterior tonsillar pillar. The tumor involves the pteryomandibular raphe and extends inferiorly to involve the inferomedial aspect of the mylohyoid muscle. Superiorly, the tumor extends along the pteryomandibular raphe to approximately of the level of the soft palate.
The tumor extends posteriorly and abuts the anterior margin of the ramus of the right mandible. The T2-weighted images demonstrate some increased T2 signal involving the anterior aspect of the ramus of the right mandible which appears to enhance on the fat-suppressed contrast-enhanced T1-weighted images. Thus, there does appear to be marrow involvement which could be due to direct tumor invasion or peritumoral edema. The posterior margin of the tumor also abuts the medial pterygoid muscle at its insertion of the ramus and the mandible.
Imaging of the neck demonstrates no definite evidence of enlarged cervical lymph nodes given standard size criteria. However, there is an asymmetrically enlarged 1.5cm right level 2 lymph node. Given that this is on the ipsilateral side of the right retromolar trigone carcinoma, this lymph node is suspicious for metastasis.
Conclusions
1. Approximately 2.5cm aggressive mass involving the right retromolar trigone with extension medially to involve the anterior tonsillar pillar and superiorly to the level of the soft palate. The lesion abuts the anterior ramus of the right mandible and is associated with some increased T2 signal and contrast enhancement which is suspicious for marrow involvement which could either be due to tumor involvement or peritumoral edema. Thin-section CT would help evaluate for cortical invasion of the anterior portion of the ramus and the mandible.
2. 1.5cm right level 2 lymph node. Given this lymph node is asymmetrically enlarged on the ipsilateral side of the tumor, these findings are suspicious for nodal metastasis and would increase the stage to N1.
