Spitz nevus

'Spitz nevus, also known as epithelioid and spindle-cell nevus, is an uncommon melanocytic lesion that can be difficult to differentiate from malignant melanoma.

General

• May be very difficult to differentiate from melanoma.

Epidemiology:

• Children & adolescents.

Treatment:

• Complete excision.

Gross

• Usually face or extremity.

Microscopic

Features:

• Architecture:
  • Nests of cells (spindle, epithelioid or spindle/epithelioid) - in both dermis and epidermis.
    • Nests are vertically arranged, i.e. the long axis of the nests are perpendicular to the skin surface.
      • Nest arrangement/orientation described as "cluster of bananas".
• +/-Hyperkeratosis (more keratin, i.e. thick stratum corneum).
• +/-Hypergranulosis (thick stratum granulosum).
• +/-Acanthosis (thick stratum spinosum).
• Kamino bodies (also written Camino bodies) - dense eosinophilic bodies.
  • Apoptotic cells.
  • Kamino bodies are rare in melanoma.

Notes:

• Never in the setting of solar elastosis.
  • If there is solar elastosis -- it's melanoma.

DDx:

• Malignant melanoma - so-called Spitzoid melanoma.
• Pigmented spindle cell nevus of Reed.

Images

• 

  Spitz nevus - low mag. (WC)

• 

  Spitz nevus - intermed. mag. (WC)

• 

  Spitz nevus - high mag. (WC)

www:

• Spitz nevus - collection of images (drmihm.com).
• Spitz nevus with arrow to camino body (unibas.ch).

IHC

• HMB-45 -ve at deep aspect.
• Ki-67 low.

See also

• Melanocytic lesions.
• Malignant melanoma.