Pigmented spindle cell (Reed) nevus

    Article Contributors: 
    Sean Klepper M.D.
    Artur Zembowicz M.D....

    Clinical Features:

    • Peak incidence in the third decade; slight female predominance
    • Most common on the extremities
    • Presents as a small, symmetric, sharply demarcated, pigmented papule or nodule of acute onset
    • The importance of recognizing this entity lies in the fact that it is often misdiagnosed as melanoma. 

    Histologic Features:

    • Junctional or compound nevus (with the junctional component often predominating)
    • The lesion displays a symmetric configuration with fairly sharply demarcated lateral borders.
    • The nevus cells are uniform spindle cells arranged in tightly packed fascicles, with relatively uniform spacing between the fascicles and with the cells often vertically oriented.
    • The spindle cells tend to be narrower than those of classic Spitz nevus, and have nuclei smaller than or equal in size to keratinocyte nuclei and inconspicuous nucleoli.
    • The nevus cells typically contain at least focall abundant coarse melanin pigment, in contrast to Spitz nevus.  The pigment may also be present within the keratinocytes and the papillary dermis.
    • The nuclei of the nevus cells become smaller as one procedes deeper into the lesion (they "mature").
    • Mitoses are often present in the junctional component, but are rare to absent in the dermal component.
    • Pigmented spindle cell nevus and Spitz nevus exist along a spectrum, and one sometimes encounters lesions with features intermediate between the two entities.
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    Cases associated with this book:

  • Pigmented spindle cell nevus
    Author: Artur Zembowicz M.D. Ph.D.

    Conference: Dermpedia Teaching Collection