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.