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Ectopic tissueMetastasis mimicICD-10 N80.6

Cutaneous endometriosis

Cutaneous endometriosis · scar endometrioma · umbilical endometriosis (Villar nodule)

Cutaneous endometriosis is the presence of functional endometrial glands and stroma within the skin — most commonly in caesarean / abdominal-surgery scars (scar endometrioma), but also in the umbilicus (Villar nodule) without prior surgery. It accounts for <1% of all endometriosis. Cyclical pain and swelling synchronous with menses is pathognomonic. The principal skin-oncology relevance is as a differential for Sister Mary Joseph nodule (umbilical metastasis) and cutaneous metastatic disease.

CurrentLast reviewed 16 May 2026
Clinical image of Cutaneous endometriosis
Cutaneous endometriosis. Image sourced from DermNet New Zealand. Used under CC BY-NC-ND 4.0. No endorsement implied.

Classification

  • Scar endometriosis (commonest cutaneous variant):
    • Caesarean-section scar (over 70%).
    • Episiotomy / perineal scar.
    • Laparoscopic / laparotomy port-site scar.
    • Implantation occurs intra-operatively from uterine tissue spillage.
  • Primary cutaneous endometriosis (no prior surgery):
    • Umbilical (Villar nodule): spontaneous; classical extra-pelvic site.
    • Inguinal / vulval.
    • Rare other sites: trunk, limbs.
  • ~0.5-1% of all endometriosis cases.

Clinical features

  • Firm subcutaneous nodule.
  • Bluish or red-brown discolouration; sometimes haemorrhagic.
  • Tender, particularly:
    • Cyclical pain / swelling synchronous with menses (pathognomonic).
    • Sometimes bleeding / serosanguineous discharge during menstruation.
  • Size: usually <3 cm but can be larger; slowly enlarging.
  • Pre-menopausal women; ages 20-40 typically.
  • Concurrent pelvic endometriosis in 25-50%.

Differentials

  • Sister Mary Joseph nodule — umbilical metastasis from internal malignancy (gastric, ovarian, colon, pancreatic) — most important DDx; biopsy if doubt.
  • Cutaneous metastasis.
  • Epidermoid cyst — non-cyclical; central punctum.
  • Keloid scar.
  • Suture granuloma.
  • Stitch / scar abscess.
  • Incisional hernia with omental fat.
  • Desmoid tumour (FAP / sporadic; abdominal-wall).
  • Granuloma, foreign-body reaction.

Investigations

  • Detailed history: cyclicity, prior surgery, gynaecological symptoms.
  • USS: heterogeneous solid mass; well-defined margins.
  • MRI: T1-hyperintense (haemorrhagic foci); useful for extent.
  • Skin biopsy / excisional biopsy: definitive diagnosis.
  • Histology: endometrial glands + stroma; haemosiderin; hormonal-cycle changes; CD10+ stroma (endometrial-stroma IHC marker).
  • If umbilical with no prior surgery, exclude internal malignancy:
    • CT abdomen / pelvis.
    • Tumour markers (CA125, CEA, CA19-9).
    • Gastroscopy / colonoscopy if clinical features.
  • Pelvic USS / MRI to screen for concurrent pelvic endometriosis.
  • Gynaecology referral.

Management

  • Surgical excision: complete local excision with 1 cm margins is curative; specimen for definitive pathology.
  • Recurrence ~5-10%; multidisciplinary planning if recurrent / extensive (cover mesh in fascial-defect surgery).
  • Medical: hormonal therapy for residual / pelvic disease — combined OCP, progestins, GnRH analogues, danazol (BMI considerations), aromatase inhibitors.
  • Long-term: multidisciplinary (plastic surgery, gynaecology, dermatology).
  • Counsel:
    • Benign nature; symptom relief excellent with excision.
    • Hormonal therapy not always required after excision unless pelvic disease.
    • Pregnancy: lesions may regress; fertility-related plans.
  • Sister Mary Joseph exclusion mandatory in umbilical disease.

References

  1. Steck WD, Helwig EB. Cutaneous endometriosis. JAMA. 1965;191:167-170.
  2. Friedman PM, Rico MJ. Cutaneous endometriosis. Dermatol Online J. 2000;6:8.
  3. Khamechian T et al. Cutaneous endometriosis: a case series and literature review. Int J Womens Dermatol. 2020;6:226-229.
  4. Dunselman GAJ et al. ESHRE guideline: management of women with endometriosis. Hum Reprod. 2014;29:400-412.
  5. NICE NG73. Endometriosis: diagnosis and management. London: NICE; 2017 (last updated 11 November 2024; reviewed 2 September 2025).

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