Spitz (Spindle and Epithelioid Cell) Nevi

Spitz (Spindle and Epithelioid Cell) Nevi
Jessica M. Comstock, MD
David Cassarino, MD, PhD
Key Facts
Clinical Issues
  • Benign melanocytic tumor
  • Most common in children and young adults
  • Common sites: Extremities, especially thigh
  • Pink or flesh-colored, dome-shaped dermal papule or nodule
Microscopic Pathology
  • Junctional, compound, and dermal forms
  • Symmetric, well circumscribed
  • Varying proportions of spindled and epithelioid melanocytes
    • Spindle cells much more common
    • Epithelioid cells usually dispersed individually throughout lesion
  • Melanocytes “mature” by becoming smaller from superficial to deep
  • Kamino bodies: Eosinophilic globules at dermal-epidermal junction
  • Artifactual clefting of papillary dermal nests from overlying epidermis often present
  • Can show atypical features (atypical Spitz nevus/tumor)
Top Differential Diagnoses
  • Spitzoid melanoma; findings suspicious for melanoma include
    • Patient > 10 years old
    • Lesion > 1 cm
    • Ulceration and increased mitoses present
    • Asymmetry and poor circumscription
    • Subcutaneous involvement
  • Pigmented spindle cell nevus of Reed
  • Conventional melanocytic nevi
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  • Benign juvenile melanoma (outdated term)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
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Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Spitz (Spindle and Epithelioid Cell) Nevi

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