OP218: Immunohistochemical profile of primary oral malignant melanomas

Abstract

Purpose Primary oral melanoma is an uncommon malignant tumor of melanocytic origin, with potentially aggressive capacity. Several immunohistochemical markers influencing invasiveness and metastatic dissemination of melanoma have been identified and used previously. Our aim was to analyze the immunohistochemical expression for cathepsin-D, c-kit, E-cadherin, cyclin D1, and MUM-1 in oral malignant melanomas. Material and Methods Immunoperoxidase staining was performed on formalin-fixed tissue specimens from oral melanoma specimens and oral melanocytic nevi lesions which were used as control group. The percentages of immunoreactive melanocytes were estimated and qualitatively abnormal immunoreactivity patterns were also tabulated. Results Cathepsin-D, c-kit, cyclin D1, and MUM-1 were highly expressed in oral melanomas, whereas negative or very weak expression of the above mentioned markers was recorded in oral melanocytic nevi lesions. E-cadherin was expressed uniform throughout the entire oral melanocytic nevi, whereas oral melanomas expressed heterogeneous E-cadherin staining. Furthermore oral melanomas showed qualitatively and quantitavely abnormal E-cadherin immunoreactivity, with gradual loss of staining and increasing lesional depth. The results indicate that cathepsin-D, c-kit, E-cadherin, cyclin D1, and MUM-1 may be involved in the development of oral melanomas, and eventually they may be useful in the differential diagnosis of oral malignant melanomas and oral melanocytic nevi lesions. Conclusions The above mentioned markers seems to correlate with oral melanoma development and have an important functional role in tumor development or progression. Melanoma has a wide spectrum of histologic features which mimic epithelial, hematologic, mesenchymal, and neural tumors. Immunohistochemistry has been the primary tool to distinguish melanomas from these other tumors. Use of immunohistochemical markers should therefore give additional information which cannot be determined by routine histopathology.