Skin melanocytic tumor
Lentigines, melanotic macules and melanocytic hyperplasia
Melanocytic hyperplasia
Author: Christopher S. Hale, M.D.
Last author update: 1 March 2013
Last staff update: 12 December 2024
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: atypical melanocytic hyperplasia
Table of Contents
Definition / general | Terminology | Case reports | Microscopic (histologic) description | Differential diagnosisCite this page: Hale CS. Melanocytic hyperplasia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumormelanocyticatypicalmelanocytichyperplasia.html. Accessed December 22nd, 2024.
Definition / general
- Controversial topic
- May coexist with benign nevi (Mod Pathol 2000;13:857)
- May occur on foot or on sun damaged skin (Arch Dermatol 1994;130:1042, J Dermatol 2007;34:56)
- Chronic sun exposure leads to 2× increase in melanocyte density, often with aytpia (J Am Acad Dermatol 2011;65:1186)
Terminology
- Also called atypical melanocytic proliferation or benign atypical junctional melanocytic hyperplasia
Case reports
- 64 year old woman with esophageal squamous cell carcinoma in situ (Virchows Arch 2000;437:203)
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
- Melanoma in situ (Am J Dermatopathol 1996;18:560)
- Pseudomelanocytic nests in lichenoid reactions (Am J Dermatopathol 2009;31:305)
