Abstract:

A 67 year-old female presented with a five month history of persistent epistaxis and nasal congestion. Endoscopic examination revealed an 8 cm posterior sinonasal mass. No additional lesions suspicious for either an alternative primary tumor or metastases were present on physical exam, including skin exam, and imaging. Biopsy of the nasal mass showed a focus of common blue nevus adjacent to, and merging with, melanoma. The melanoma component showed a predominantly spindled morphology with brisk mitotic activity, prominent nucleoli, and pleomorphism with occasional bizarre forms. There was an abrupt transition between the tumor cells and necrotic areas with karyorrhexis in keeping with tumor-type necrosis. The lesion's size(1), proliferation rate(2), and type of necrosis(3) favored a diagnosis of malignancy. Immunohistochemically, both the common blue nevus and melanoma components were positive for SOX-10, HMB45, and MelanA. Ki-67 proliferation index was 30% in the melanoma component and 1% in the blue nevus component. p16 showed diffuse and strong nuclear positivity in the blue nevus and loss of nuclear staining in the melanoma, while Cyclin D1 showed the opposite staining pattern (positive in the melanoma; negative in the blue nevus). A focused next-generation sequencing panel including GNAQ, GNA11, and BRAF was pending at the time of this report. Although uncommon, blue nevi and melanomas in the sinonasal tract are well-documented. While melanomas arising in association with blue nevi have been reported in the skin(2), this case represents the first reported instance of sinonasal melanoma arising from a common blue nevus.

Financial Disclosure:
No current or relevant financial relationships exist.

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Arjun Mehta