Skin melanocytic tumor
Minimal deviation melanoma

Author: Christopher Hale, M.D. (see Authors page)

Revised: 14 September 2018, last major update May 2013

Copyright: (c) 2002-2018,, Inc.

PubMed Search: Minimal deviation melanoma

Cite this page: Hale, C. Minimal deviation melanoma. website. Accessed September 25th, 2018.
Definition / general
  • First described by Reed (Semin Oncol 1975;2:119)
  • Controversial topic / diagnosis (Mod Pathol 2006;19:S41) which may not have clinical significance (Melanoma Res 2000;10:371) - concept is not universally accepted
  • Introduced to embrace the concept that a subset of invasive melanomas is characterized by lesser cytologic atypia and a better prognosis than conventional melanomas of the same thickness
  • Cells are more atypical than nevi but less atypical than classic melanoma
  • Also called borderline melanocytic lesion
Clinical features
  • Plaque or nodule, fleshy, dark brown or bluish black and up to 1 cm
  • May resemble an epidermal cyst
Microscopic (histologic) description
  • Expansive nodule in vertical growth phase that fills papillary dermis and may extend into reticular dermis (Mod Pathol 2006;19:S41)
  • Usually uniform cells with mild to moderate atypia that resemble nevus cells but are moderately enlarged with irregular chromatin and increased N / C ratios
  • Growth displaces surrounding structures and remnants of residual benign nevus are often present
  • Equivalent to at least a level III melanoma due to extent of dermal invasion
  • May have perineural invasion and mitotic figures but usually does not invade subcutaneous fat; no necrosis, no maturation
  • Variants: Spitz, halo nevus-like (Am J Surg Pathol 1990;14:53), spindle cell (Pediatr Pathol 1988;8:401), desmoplastic, small cell and dermal
Positive stains
Differential diagnosis