A Case of Amelanotic Malignant Melanoma of the Maxillary Sinus Presented with Intraoral Extension

Melanoma of the sinonasal cavity has a high incidence of amelanotic presentation. Its diagnosis is difficult for clinicians and pathologists because of its hidden location and lack of pigmentation at the microscopic level. We reported a case of amelanotic melanoma of the maxillary sinus that showed aggressive extension to the oral cavity after extraction of the maxillary tooth. Histologically, the lesion resembled a plasmacytoid tumour. Diagnosis was made through the positive immunohistochemical staining for S100 and HMB-45.