A 77-year-old woman visited us complaining of a nasal macule that had been gradually enlarging for 14 months. Previous topical corticosteroid application was ineffective. Physical examination revealed a hemorrhagic erythematous lesion with crust measuring 36 × 30 mm in diameter on the right side of her nose. On dermoscopy, telangiectasia and arborizing vessels were conspicuous without any pigmented spots or dots. Histopathologically, atypical basaloid cells were found to be proliferating in nests with peripheral palisading. However, melanin granules in the nests and peritumoral melanophages were not found, leading us to the diagnosis of non-pigmented basal cell carcinoma. Further immunohistological examination elucidated that Melan-A-positive melanocytes existed in the tumor nests; however, they were not stained by tyrosinase and Fontana-Masson staining. These results indicated that the inhibition of eumelanin biosynthesis in melanocytes would explain the hypopigmented nature of her basal cell carcinoma.
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