Skin melanocytic tumor
Other pigmented lesions and disorders of pigmentation
Atypical melanocytic hyperplasia

Author: Christopher Hale, M.D.

Revised: 31 August 2018, last major update March 2013

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

PubMed Search: atypical melanocytic hyperplasia

Cite this page: Hale, C.S. Atypical melanocytic hyperplasia. website. Accessed October 16th, 2018.
Definition / general
  • Also called atypical melanocytic proliferation or benign atypical junctional melanocytic hyperplasia
Case reports
Microscopic (histologic) description
  • Atypical single unit melanocytes limited to epidermis, often seen at periphery of classic melanoma
  • In contrast to melanoma in situ, exhibits only focal confluence at dermoepidermal junction, has limited pagetoid spread and involves only upper hair follicle
  • Factors favoring atypical melanocytic hyperplasia over melanoma in situ (Mod Pathol 2000;13:857):
    • No lateral spread
    • No upward extension into epidermis
    • No finely granular, "smoky" melanin
    • No marked cytologic atypia
    • No mitotic figures
    • No host inflammatory fibrotic response
Differential diagnosis