The many faces of blue nevus: A clinicopathologic study

Background: In recent years, several histopathologic variants of blue nevus have been identified, whose clinical and dermoscopic correlates need further clarification. Methods: A comparative evaluation of histopathologic and dermoscopic features was carried out on 52 melanocytic proliferations belonging to the morphologic spectrum of blue nevus. Results: On dermoscopy, all lesions showed a homogeneous, structureless pigment pattern, with a curious variety of colors (blue, white-blue, black, brown, and polychromatic). Histopathologically, the majority of blue lesions were common blue nevi (11/19); the majority of white-blue lesions were 'hypochromic' (sclerotic, hypomelanotic, and amelanotic) blue nevi (17/22); all the black lesions were 'compound' blue nevi (2/2); the majority of brown lesions were combined blue nevi (3/4); the unusual polychromatic dermoscopic appearance was often associated with a histopathologic diagnosis of deep penetrating nevus (2/5). Conclusions: A dermoscopic-pathologic approach now allows us to identify 'blue' (common) blue nevi, 'white' (hypochromic) blue nevi, 'black' (compound) blue nevi, 'brown' (combined) blue nevi, and 'polychromatic' (deep penetrating) blue nevi. A better recognition of the many dermoscopic faces of blue nevi is expected to give a morphologic guideline for the clinical management of these lesions.