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Cutaneous endometriosis

Author: Brian Wu PhD. MD Candidate, Keck School of Medicine, Los Angeles, USA; Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, November 2015.

Cutaneous endometriosis — codes and concepts

What is endometriosis?

The endometrium is the lining of the uterus (womb). Endometriosis is the growth of endometrial tissue outside the uterus. It usually arises close to the uterus within the pelvis — the lower part of the abdomen. The mass is also called an 'endometrioma'. Endometriosis outside the pelvis occurs in about 12% of women with endometriosis.

What is cutaneous endometriosis?

Cutaneous endometriosis is endometriosis in the skin and is rare. It was first described by Villar in 1860. It commonly occurs in a surgical incision from a previous gynaecological or abdominal surgery, such as caesarian section, hysterectomy or laparoscopic surgery but can also develop spontaneously. It also called 'scar endometriosis'.

The most common sites for cutaneous endometriosis are the abdominal wall, the umbilicus and the extremities.

What causes cutaneous endometriosis?

There are two theories regarding the cause of spontaneous cutaneous endometriosis.

  • The transportation theory states that endometrial cells are transported outside the uterus via the lymphatic system or another route.
  • The metaplasma theory states that endometrial cells may develop in the coelomic mesothelium in the presence of high oestrogen levels or another stimulus.

What are the clinical features of cutaneous endometriosis?

Women with cutaneous endometriosis can present with the following signs and symptoms.

  • A palpable subcutaneous mass; this can cramp and bleed during the monthly period and is sometimes dubbed a “menstruating tumour”.
  • The mass is generally firm and may be blue, black, brown or red in colour
  • Typical size range for the mass averages 0.5–6 mm in diameter.
  • The patient can complain of itching, swelling or tenderness.
Cutaneous endometriosis in the perineum

What complications stem from cutaneous endometriosis?

Complications from cutaneous endometriosis include:

  • Local recurrence after surgical excision
  • Development of endometrial carcinoma (this is rare)

Malignancy should be suspected if the mass is abnormally large, has grown rapidly, or has recurred after previous excisions.

How is cutaneous endometriosis diagnosed?

Diagnosis of cutaneous endometriosis is based upon:

  • Patient history, including gynaecological and surgical history
  • Physical examination
  • Echography (ultrasound test)
  • Doppler examination of the soft tissues of the abdominal wall
  • Computer tomography
  • Magnetic resonance imaging
  • Skin biopsy

Histopathology is the key to accurate diagnosis and detects endometrial glands, stroma and haemosiderin if present.

Diagnosis is often delayed due to confusion with other conditions, including haematoma, neuroma, hernia and neoplastic tissue.

What is the treatment for cutaneous endometriosis?

The main treatment for cutaneous endometriosis is surgical excision of the mass, preserving the umbilicus whenever possible and if relevant.

Medical therapy uses the hormones danazol, progesterone, and Gonadotrophin Releasing Hormone (GnRH).

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