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Melanocytic · Spitzoid

Spitz naevi & atypical Spitz tumours

Spitz naevus; spindle and epithelioid cell naevus; atypical Spitz tumour (AST); spitzoid melanoma

Spitz naevi are benign melanocytic naevi with characteristic spindle and epithelioid melanocytes. The clinical and histological challenge is distinguishing benign Spitz naevus from atypical Spitz tumour from spitzoid melanoma — molecular profiling (kinase fusions, HRAS mutations) and ancillary techniques (FISH, CGH) increasingly inform the assessment.

CurrentLast reviewed 25 March 2026
Classical Spitz naevus, child
Classical Spitz naevus — pink, dome-shaped, well-circumscribed papule on the face of a child or young adult.

Clinical features

Spitz naevi typically present as a solitary, rapidly growing, dome-shaped, pink to brown papule, usually on the face or limb of a child or young adult. Adults can also develop new Spitz lesions; rapid growth in this group is more concerning. Pigmented variants (Reed naevus) show characteristic starburst dermoscopy.

Dermoscopy

  • Symmetrical starburst pattern — peripheral pseudopods or streaks radiating from a central darker zone (Reed-type).
  • Symmetrical globular pattern in younger lesions.
  • Pink-vascular pattern with regular dotted vessels in non-pigmented Spitz.
  • Loss of symmetry, asymmetric pseudopods, polymorphous vessels or atypical pigment network → concerning for spitzoid melanoma.

Histology & molecular

Histology shows large epithelioid and spindle melanocytes in vertical fascicles, often with Kamino bodies, hyperplastic epidermis and clefts. The traditional histopathological criteria for atypia were unreliable — molecular profiling has reshaped the field.

Molecular subgroups (Bastian)

  • HRAS mutation — typical of benign desmoplastic Spitz.
  • Kinase fusions — ALK, ROS1, NTRK1, NTRK3, RET, MET, BRAF, MAP3K8 — recurrent in Spitz lesions including atypical and malignant.
  • BAP1-inactivated melanocytic tumours — domed pink papules often in BAP1-TPDS.

Ancillary tests: FISH (myc amplification suggests melanoma), CGH (multiple chromosomal aberrations), 9p21 loss (CDKN2A homozygous deletion strongly favours malignancy).

Management

  • Classical Spitz in a child: if dermoscopy is symmetrical and stable, observation is acceptable; many lesions involute.
  • Adult Spitz / atypical Spitz: excisional biopsy with narrow margin; specialist dermatopathology review; molecular ancillaries.
  • Atypical Spitz tumour (AST): wide local excision with 5–10 mm margin per regional MDT recommendation; consider SLNB (controversial — positive SLN does not necessarily indicate malignant behaviour in spitzoid lesions).
  • Spitzoid melanoma: manage as conventional melanoma per melanoma monograph.
Clinical pearlSpecialist review

Atypical Spitz tumours are often best managed via specialist dermatopathology review and molecular ancillaries — the histological grey zone is wide and management implications considerable.

References

  1. Cerroni L et al. Melanocytic tumors of uncertain malignant potential. Am J Surg Pathol; 2010.
  2. Bastian BC. Spitz tumors and the kinase fusion paradigm. Nat Rev Cancer; 2014.
  3. Cesinaro AM et al. Spitz tumors: a comprehensive review. Pathology; 2020.

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