Cutaneous endometriosis occurs when uterine-like tissue grows on the skin.

Endometriosis can be cutaneous, which means affecting the skin, or subcutaneous, which happens beneath the layers of skin.

Cutaneous endometriosis is rare, making up less than 1% of all cases.

Primary cutaneous endometriosis refers to cells that develop spontaneously without a history of abdominal or pelvic surgery.

Secondary cutaneous endometriosis is the most common explanation for scar endometriosis and is assumed to occur during abdominal or pelvic surgery.

The symptoms of cutaneous endometriosis can resemble more common conditions like keloid, making the disease challenging to diagnose.

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

Cutaneous endometriosis can present as a nodule on or below the skin. The lesions are typically firm and measure between .05–6 millimeters (mm) in diameter.

The mass may cramp and bleed along with your menstrual cycle and may be black, blue, red, or brown. Other symptoms include itching, swelling, and tenderness.

There are two theories on what causes endometriosis, but more research is needed for a definitive answer.

The metaplasma theory suggests that the body produces the cells in response to high estrogen levels or another catalyst.

The transportation theory states that the cells are transported outside the uterus by the lymphatic system or vascular pathways.

Depending on where the lesion is located, endometriosis can be considered endopelvic or extrapelvic/extragenital.

Cutaneous endometriosis falls under the subtype of extrapelvic endometriosis.

Extrapelvic endometriosis is rare and can occur in the urinary tract, abdominal wall, urinary and gastrointestinal tract, brain, skin, and lungs.

It’s thought that certain surgical procedures can transplant tissue from the pelvic cavity to the surgical site, resulting in implantation onto the skin.

Cutaneous scar endometriosis is associated with hysterectomy, episiotomy, and cesarean section.

A diagnosis of cutaneous endometriosis is often delayed due to the symptom’s similarities to other diseases, including:

Fine needle aspiration and histopathology are the most accurate diagnosis methods. These tests detect endometrial glands, stroma, and hemosiderin.

Your clinician may also request the following:

  • physical exam
  • ultrasound
  • doppler exam of the soft tissue of the abdominal wall
  • CT scan
  • MRI

The most common treatment for cutaneous endometriosis is surgical excision.

Removing the lesion in a wide-margin excision is the gold standard of surgical therapy. The incision should be at least 1 centimeter (cm) away from the solid tissue to prevent further spreading of endometrial-like cells.

Your clinician may prescribe hormone therapy in conjunction with surgery. Hormones can help shrink the nodule.

Hormone therapy can also be used alone to help manage your symptoms.

There are some complications associated with cutaneous endometriosis. The scar could reappear after surgical excision. You may also develop endometrial carcinoma, which is rare.

If a mass is growing rapidly and is abnormally large or has returned after a previous excision, your physician should investigate the malignancy of the nodule.

Hormonal treatments are effective only for as long as you take them. Discontinuing medication could result in the cells returning.

Cutaneous endometriosis is a rare form of endometriosis where uterine-like tissue grows and sheds on the skin.

Symptoms can include cyclic bleeding, swelling, and pain at the site of the lesion.

Your clinician will use your medical history and some testing to determine the best treatment options. You’ll have the final say on what treatment feels right to you.

Catasha Gordon is a sexuality educator from Spencer, Oklahoma. She’s the owner and founder of Expression Over Repression, a company built around sexual expression and knowledge. You can typically find her creating sex education materials or building some kinky hardware in a fresh set of coffin nails. She enjoys catfish (tail on), gardening, eating off her husband’s plate, and Beyoncé. Follow her everywhere.