blue nevus n a small blue or bluish black spot on the skin that is sharply circumscribed, rounded, and flat or slightly raised and is usu. benign but often mistaken for a melanoma
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a benign, usually solitary type of melanocytic nevus, representing a localized proliferation of melanocytes in the dermis. It is a dark blue to black, moderately firm, rounded, sharply defined nodule containing spindle-shaped melanocytes with slender cytoplasmic processes, and is generally seen in association with melanin-laden macrophages in a sclerotic dermis. Called also dermal melanocytoma and Jadassohn-Tiиche n.Medical dictionary. 2011.