Skin - Nonmelanocytic tumors
Other tumors of skin

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

Revised: 4 October 2016, last major update September 2012

Copyright: (c) 2001-2016,, Inc.

PubMed search: endometriosis [title] skin

Cite this page: Endometriosis. website. Accessed October 21st, 2016.
Definition / General
  • Ectopic endometrial tissue, usually described in pelvic organs, but 0.5% - 1.0% of cases are cutaneous
  • Women of reproductive age, often due to iatrogenic seeding of umbilicus during C-section (Villar’s nodule) but may occur in almost any site
  • Carcinoma rarely arises in preexisting endometriosis
  • Women with endometriosis may have mildly increased risk of melanoma (Int J Epidemiol 2009;38:1143)
Case Reports
  • Gonadotropin releasing hormone analogues
  • Excision
Gross Description
  • Dark red to bluish nodule, may form cystic structure
Gross Images
Images hosted on other servers:

Villar's nodule

Micro Description
  • Endometrial glands, endometrial stroma and hemorrhage
  • May have marked decidual changes
Micro Images
Images hosted on other servers:

Endometriosis in periumbilical dermis

Various images

Positive Stains
Negative Stains
Differential Diagnosis
  • Sweat gland tumor
  • Urachal duct cyst
  • Pyogenic granuloma
  • Hernia
  • Residual embryonic tissue
  • Primary or metastatic adenocarcinoma (Sister Joseph's nodule)
  • Cutaneous endosalpingiosis