May be more common on head and neck
Microscopic
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Lesion overall orderly, symmetric, and well circumscribed
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Most commonly: Compound/intradermal melanocytic nevus plus blue nevus
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Others types of combined nevi include compound or intradermal nevus plus pigmented spindle or spitzoid cells
Top Differential Diagnoses
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Blue nevus (common and cellular types)
Composed of dendritic to spindled melanocytes and melanophages
Cellular often shows deep extension into dermis/subcutaneous
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Deep penetrating nevus
Wedge-shaped architecture
Often deep extension into dermis/subcutaneous
Junctional nests may be present
Dermal component composed of epithelioid/spindled melanocytes in nests bordered by melanophages
Nests/fascicles of cells may be centered around adnexal/neurovascular structures in dermis
Occasionally, bulbous/pushing margin is present
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Congenital melanocytic nevus: Present at birth
May extend deep into dermis or subcutaneous tissue
May infiltrate arrector pili, adnexal structures, nerves
Maturation with depth
TERMINOLOGY
Synonyms
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Melanocytic nevus with phenotypic heterogeneity, clonal nevus, nevus with focal epithelioid component, combined Spitz nevus, inverted type A nevus
Definitions
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Presence of 2 or more distinct populations of melanocytes (i.e., type A melanocytic nevus cells and spindled or dendritic cells)
or
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Presence of 2 or more types of melanocytic nevi (i.e., intradermal melanocytic and blue or Spitz)
CLINICAL ISSUES
Presentation