Skin nonmelanocytic tumors
Other tumors of skin

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

Revised: 14 September 2018, last major update September 2012

Copyright: (c) 2001-2018,, Inc.

PubMed search: endometriosis [title] skin

Cite this page: Hale, C. Endometriosis. website. Accessed December 12th, 2018.
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 nodule

Microscopic (histologic) description
  • Endometrial glands, endometrial stroma and hemorrhage
  • May have marked decidual changes
Microscopic (histologic) 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