A RARE CASE OF AMELANOTIC MELANOMA IN THE ORAL CAVITY

Abstract

Amelanotic melanoma (AM) is a rare malignant lesion that presents a diagnostic challenge due to its wide clinical presentations, lack of pigmentation, and varied histologic appearances. Immunohistochemistry plays a crucial role in the diagnosis. We report a case of a 45-year-old male patient with a red and bleeding growth on the mandibular gingiva, resembling a pyogenic granuloma. An incisional biopsy was performed, and the histopathologic analysis was characterized by proliferation of nests and sheets of nonpigmented atypical epithelioid and plasmacytoid cells displaying a poorly delimited cytoplasm and hyperchromatic nucleus. Immunohistochemistry showed multifocal staining for melanocytic markers, S100 protein, HMB-45, Melan-A, and Ki-67 (95%). These findings confirmed the diagnosis of AM. The patient was referred to the oncologist who observed disease progression to the lungs, liver, and pancreas. The patient was under palliative care and medical follow-up but died. AM has a poor prognosis, with a high incidence of metastasis, recurrence, and death. Amelanotic melanoma (AM) is a rare malignant lesion that presents a diagnostic challenge due to its wide clinical presentations, lack of pigmentation, and varied histologic appearances. Immunohistochemistry plays a crucial role in the diagnosis. We report a case of a 45-year-old male patient with a red and bleeding growth on the mandibular gingiva, resembling a pyogenic granuloma. An incisional biopsy was performed, and the histopathologic analysis was characterized by proliferation of nests and sheets of nonpigmented atypical epithelioid and plasmacytoid cells displaying a poorly delimited cytoplasm and hyperchromatic nucleus. Immunohistochemistry showed multifocal staining for melanocytic markers, S100 protein, HMB-45, Melan-A, and Ki-67 (95%). These findings confirmed the diagnosis of AM. The patient was referred to the oncologist who observed disease progression to the lungs, liver, and pancreas. The patient was under palliative care and medical follow-up but died. AM has a poor prognosis, with a high incidence of metastasis, recurrence, and death.