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Neuroradiology Case of the Week

Case 385

February 2009

Richard Gong, MD and Sam McCabe, MD

Clinical Presentation: A 63-year-old female with history of adenocarcinoma of the colon initially presented to her physician with a swollen left parotid gland. Presumptive diagnosis of saldenitis was made and the patient was treated with antibiotics. After no response to antibiotics, MRI was performed. Subsequently a fine needle aspiration of the left mandibular mass was performed demonstrating malignant cells derived from adenocarcinoma with mucinous features similar to prior pathology slides of patient's colonic adenocarcinoma.

Imaging Findings: MR axial T1 image demonstrates a large mass causing destructive changes in the left mandible (Fig.1). The mass demonstrates high T2 signal (Fig. 2) and enhances vividly post-contrast (Figs. 3 and 4).

Diagnosis: Mandibular metastasis from colonic adenocarcinoma

Discussion: Metastatic disease in the oral cavity is rare, representing approximately 1% of all neoplasms in the oral cavity. Within the oral cavity, the mandible is the most common subsite for metastasis. This may be due to a relatively higher amount of active red bone marrow compared to the maxilla. Metastasis to the mandible is via the blood secondary to the absence of a lymphatic system in the mandible. The blood supply to the molar region is more abundant than the mental mandible and the highest amount of red marrow in the mandible is at the third molar region. It is hypothesized that these are the reasons why there is a higher rate of metastasis at the posterior mandible.
     The most common primary sites in females are breast, adrenal glands, colon, female genital tract, and thyroid. In men, the most common primary sites are lung, prostate, kidney, bone, and adrenal gland. Approximately one third of patients present with an oral lesion as the first sign of their primary malignancy.
     Metastatic lesions to the mandible may mimic odontogenic infections or other conditions in the oral cavity, leading to late diagnosis. Metastatic tumor should always be considered in the differential diagnosis of any lesion in the mandible. Decreased frequency of involvement may reflect the low proportion of cancellous bone in the mandible and maxilla. The relatively large pocket of cancellous bone at the mandibular angle is thought to account for the high proportion (75%) of mandibular/maxillary metastases that involve this area. Most jaw bone masses reflect metastases from adenocarcinoma. Primary tumors of the jaw bones, such as osteosarcoma, are exceedingly rare.
     Symptoms are nonspecific and include loose teeth, swelling, local or referred pain, and paresthesias.
     A primary tumor has usually already been diagnosed in patients with mandibular metastases, and widespread metastatic disease is common.
     Treatment depends on the extent of disease, but aggressive local therapy is indicated in the rare setting of isolated mandibular metastasis.

References:

1. Mojica-Manosa P, Rigual N, Tan D, Sullivan M. An unusual case of a metastatic adenocarcinoma of the rectum to the mandible: a case report and review of the literature. J Oral Maxillofac Surg. 2006 Sep;64(9):1436-9. [PubMed]
2. Tamiolakis D, Tsamis I, Thomaidis V, et al. Jaw bone metastases: four cases. Acta Dermatovenerol Alp Panonica Adriat. 2007 Mar;16(1):21-5. [PubMed]
3. Hwang EH, Hwang JY, Lee SR. Metastatic adenocarcinoma of the mandible. Korean J Oral Maxillofac Radiol. 2004 Dec;34(4):219-223. [KoreaMed]