Spitz (Spindle and Epithelioid Cell) Nevi



Spitz (Spindle and Epithelioid Cell) Nevi


Jessica M. Comstock, MD

David Cassarino, MD, PhD










A pink papule, typical of a Spitz nevus, is shown on the face of a child. (Courtesy R. J. Antaya, MD.)






High-power examination of a Spitz nevus shows small nests of epithelioid to spindled melanocytes with overlying artifactual clefting image and an eosinophilic Kamino body image.


TERMINOLOGY


Synonyms



  • Spindle and epithelioid cell nevus


  • Spindle cell nevus


  • Epithelioid cell nevus


  • Nevus of large spindle &/or epithelioid cells


  • Benign juvenile melanoma (outdated term)


CLINICAL ISSUES


Site



  • Extremities, especially thigh


  • Trunk


  • Head and neck


Presentation



  • Most common in children and young adults



    • 0.5-1% of all nevi in children and adolescents


    • May occur at all ages


  • Solitary



    • Can be clustered or disseminated


Treatment



  • Complete conservative excision


Prognosis



  • Benign


  • Low recurrence rate, even after incomplete excision


MACROSCOPIC FEATURES


General Features



  • Dome-shaped dermal nodule


  • Pink or flesh-colored


  • Often misdiagnosed clinically as hemangioma or pyogenic granuloma


Size



  • Usually < 1 cm


MICROSCOPIC PATHOLOGY


Histologic Features



  • Junctional, compound, and dermal forms



    • Most common type is compound with prominent dermal component


  • Symmetric, well-circumscribed proliferation



    • Usually no lateral extension of junctional nests beyond dermal component


  • Varying proportions of spindled and epithelioid melanocytes



    • Spindle cells more common in most cases



      • Completely spindle cells in ~ 45% of Spitz nevi


      • Mixed spindle and epithelioid cells in ~ 35%


      • Only epithelioid cells in ~ 20%


    • Epithelioid cells usually dispersed individually throughout lesion


  • Spindle cells are arranged in fascicles perpendicular to epidermis


  • Small clusters of melanocytes can be seen in epidermis



    • Can see pagetoid spread of a few single melanocytes


  • Artifactual clefting of junctional nests from overlying epidermis


  • Kamino bodies



    • Eosinophilic globules at dermal-epidermal junction


    • Important diagnostic clue, but may need step sections to find


    • PAS and trichrome positive


  • Melanocytes “mature” by becoming smaller from superficial to deep



    • Melanocytes taper to narrow point in deep dermis, forming upside-down triangle


    • Deep melanocytes may resemble ordinary nevus cells


    • Important clue for differentiating from melanoma


  • Other unique features


Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Spitz (Spindle and Epithelioid Cell) Nevi

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