Melanoma Metastasis to the Mandible—Case Report and Comprehensive Literature Review

Incidence rate of metastases in the oral cavity: a review of all metastatic lesions in the oral cavity

Background

Metastases in the oral cavity are rare and account for only 1 to 3% of all malignant lesions in this area. The primary location from which most metastases have been described in the oral cavity in adult patients include lungs, breasts, kidneys and colon.

Material and Methods

A systematic search of the literature was carried out following the PRISMA statement in PubMed database. Clinical trials and case series published in the last 10 years [2010-2020] were eligible to be selected. The headings and keywords used in the searches were “cancer” AND “oral metastases”, “incidence” AND “oral metastases”, “oral metastases” AND “jaw bone”, “oral metastases” AND “soft tissue”.

Results

For the study of the incidence of metastases in the oral cavity, 9 reports of clinical trials and 7 retrospective studies of case series have been included in this article. The primary locations from which more metastases have been described in the oral cavity are lungs (30.6% or 183 cases), breasts (22.2% or 133 cases), liver (15.5% or 93 cases), prostate (9 % or 54 cases), thyroid glands (8.1% or 49 cases), kidneys (7.3% or 44 cases), skin (2.3% or 14 cases), soft tissues (2% or 12 cases), colon (2% or 12 cases) and gastrointestinal (0.6% or 4 cases). These metastases have a predilection for hard tissues. The clinical presentation of these lesions varies from painless granulomatous lesions to lytic areas in the jaws.

Conclusions

Although metastases in the oral cavity is an uncommon pathology, early diagnosis is needed so that in the event that it is the first manifestation, it allows the primary tumor to be diagnosed as soon as possible.

Key words:Cancer, oral metastases, incidence, jaw bone, soft tissue.

Metastatic amelanotic melanoma to the mandible mimicking benign odontogenic neoplasm

Metastatic lesions to the jaws are rare and represent about 1% of all malignancies in the oral cavity. They are not usually considered as part of the differential diagnosis due to their paucity and unusual clinico-pathological features leading to diagnostic challenges. We report on a rare case of metastatic melanoma to the anterior mandible in a 58 year old Caucasian female that mimicked benign odontogenic tumour. The lesion posed a diagnostic challenge as it clinically and radiographically presented as a well-defined radiolucency with minimal bony destruction and no pigmentation or ulceration of the oral mucosa. Histological examination was also challenging as the lesion was not part of the differential diagnosis and a process of exclusion was employed to narrow the possible diagnoses. The tumour cells were immunoreactive with S100, HMB45 and SOX10 which raised the suspicion of melanoma. MELAN A confirmed the diagnosis of amelanotic melanoma. The patient underwent resection of the mandible with neck dissection and fibula free flap reconstruction. In conclusion, clinicians should always keep in mind that melanoma has diverse clinico-pathological presentations and hence is known as "the great mimicker". It should always be suspected in patients who present with unusual lesions in the jaws that do not conform to other more common odontogenic neoplasms.