Cellular blue nevus

    Article Contributors: 
    Sean Klepper M.D.
    Stephen Lyle, M.D., ...

    Clinical Features:

    • Most common in children and young adults
    • Presents as a well-circumscribed 1- to 2-cm blue to black area of discoloration, most commonly on the buttocks, sacral area or scalp
    • Rarely recurs
    • Rare transformation to melanoma (malignant blue nevus)

    Histologic Features:

    • Cellular lobular mass, or sometimes multiple lobules, centered on the reticular dermis and sometimes extending into the subcutaneous fat
    • The inferior margin of the lesion is well defined displays a rounded, bulging appearance.
    • At least one third of the lesion is composed of round to oval to fusiform cells with variable amounts of melanin and often relatively clear cytoplasm.
    • The cells may show mild pleomorphism and occasional mitoses, but if two or more mitoses per square mm are seen, the lesion should be carefully evaluated for features of malignancy.
    • The nevus cells are usually arranged in nests or bundles of fascicles, which may or may not be encapsulated by fibrous tissue.
    • The fibrous tissue surrounding the nests often contains pigmented dendritic melanocytes and melanophages.
    • Cystic degeneration of the nests is common, particularly in the central aspect of the lesions, secondary to ischemia.  Edema, myxoid degeneration, reduced cellularity and increased melanophages are seen.
    • Many cases show a component of common blue nevus in addition to the cellular blue nevus pattern ("biphasic pattern").
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    Cases associated with this book:

  • Cellular blue nevus
    Author: Stephen Lyle, M.D., Ph.D.

    Conference: Dr. Z's Consultations