Exophytic Tumor Growth After Incomplete Removal of Polypoid Malignant Melanoma of the Maxillary Gingiva: A Case Report and Review of the Literature

Polypoid malignant melanoma of the oral cavity is extremely rare. This report describes the case of the 3-time occurrence of a polypoid malignant melanoma of the maxillary gingiva in an 84-year-old woman who had removed the primary tumor by herself. The second polypoid malignant melanoma was a black 7-cm pedunculated mass surrounded by pigmented mucosa. Histologically, the tumor exhibited an ulcerated surface lined by squamous cells and contained polygonal cells with brown-and-black pigmentation. The third polypoid malignant melanoma was observed at the same location 7 months after surgery; it was a black hemorrhagic mass approximately 1.5 cm. Histologic analysis showed morphologic findings that were similar to those observed in the second polypoid melanoma. The patient died of lung metastasis 28 months after the second surgery. This report also reviews the 5 previously reported cases of polypoid malignant melanoma of the oral cavity, all of which occurred in the upper jaw. In 2 cases, initial exophytic growth of the tumor before invasion of the submucosa and relatively early detection resulted in a good prognosis. However, in 1 case, amelanotic melanoma located in the periodontal tissues was clinically misdiagnosed as epulis. Therefore, immunostaining for S-100 and HMB-45 should be considered for nonpigmented epulis-like lesions, and wide surgical resection of primary polypoid malignant melanomas at an early stage should result in a favorable prognosis.