PNL2 melanocytic marker in immunohistochemical evaluation of primary mucosal melanoma of the head and neck.

Overview

BACKGROUND: Histologic diagnosis of mucosal melanoma of the head and neck is difficult, requiring immunohistochemical stains which are less reliable than in cutaneous lesions. PNL-2 is a novel marker that has not been examined in mucosal melanoma. METHODS: Nine formalin-fixed tissue sections of mucosal melanoma were stained with PNL-2, human melanoma black (HMB)-45, Melan-A, S-100, and microphthalmia transcription factor (MITF). RESULTS: Disease in all 9 patients arose from the sinonasal mucosa. Rates of diffuse positive staining with the 4 stains were PNL-2 (77.8%), HMB-45 (77.8%), Melan-A (50%), S-100 (87.5%), and MITF (40%). In 3 patients, PNL2 staining was superior to Melan-A or MITF. CONCLUSION: We report the first characterization of PNL-2 staining in head and neck mucosal melanoma. PNL-2 demonstrates high sensitivity for mucosal melanoma, likely superior to Melan-A and MITF, and comparable to HMB-45, with specificity superior to S-100. We advocate inclusion of PNL2 as an important adjunctive marker in the evaluation of these lesions.