Endometriosis
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Abdominal Wall Endometriosis and Malignant Transformation

Abdominal Wall Endometriosis and Malignant Transformation

Table of Contents

Video Description

This video describes a case of malignant transformation of abdominal wall endometriosis. In this video, we present contemporary data on malignant transformation of abdominal wall endometriosis. We propose strategies at the time of laparoscopy and cesarean section to reduce the incidence of abdominal wall endometriosis and associated malignancies.

Presented By

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Dr. Lauren Andrew
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Dr. Liane Belland
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Affiliations

University of Calgary

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What is Abdominal Wall Endometriosis and Malignant Transformation?

Abdominal wall endometriosis (AWE) is a rare form of endometriosis where endometrial-like tissue grows on the abdominal wall, often near surgical scars from cesarean sections or pelvic surgeries. This tissue responds to hormonal changes, causing cyclical pain, swelling, or bleeding at the site, especially during menstruation.

In extremely rare cases, this ectopic endometrial tissue can undergo malignant transformation into cancer, typically endometrioid or clear cell carcinoma. Such transformations are very rare but pose clinical challenges due to their aggressive nature and risk of spread.

  • Symptoms: Presents as pain, palpable mass, and swelling near previous surgical scars.
  • Diagnosis: Involves imaging (ultrasound, MRI) and, occasionally, biopsy to confirm.
  • Malignant Transformation: Rare; may result from chronic inflammation or insufficient removal of endometriotic tissue.
  • Treatment: Surgical excision is standard for AWE. Malignancy requires wider surgical resection, possibly with chemo or radiotherapy.

Early diagnosis and treatment of AWE reduce the risk of malignant transformation, though this remains uncommon. Regular monitoring for atypical symptoms aids in early detection of potential malignancy.

What are the Risks of Abdominal Wall Endometriosis and Malignant Transformation? 

Abdominal wall endometriosis (AWE) and its potential for malignant transformation present several risks that can impact a patient’s health and quality of life. Below are the primary risks associated with AWE and its rare progression to malignancy:

  • Pain and Discomfort: Causes localized pain, palpable mass, and swelling near surgical scars, especially during menstruation, potentially leading to chronic discomfort.
  • Bleeding and Swelling: Ectopic endometrial tissue may cause visible bleeding and cyclical swelling at the site, worsening with hormonal changes.
  • Risk of Malignant Transformation: Rare but possible; chronic inflammation or incomplete excision of endometriotic tissue can increase the likelihood of cancerous changes, typically resulting in endometrioid or clear cell carcinoma.
  • Complications from Malignancy: Malignant transformation may lead to aggressive tumor growth, higher risk of metastasis, and need for extensive treatment.
  • Recurrence: Even after treatment, AWE can recur, especially if not fully excised, necessitating further monitoring and possible re-intervention.

Early diagnosis and comprehensive treatment of AWE are essential to minimize these risks and improve outcomes, particularly in preventing recurrence and addressing any potential for malignancy.

Video Transcript: Abdominal Wall Endometriosis and Malignant Transformation

In this video we describe a case of malignant transformation of an abdominal-wall endometriosis. Our objectives for this video are to present contemporary data on malignant transformation of abdominal-wall endometriosis, through a case presentation and ultimately to propose approaches to decrease abdominal-wall endometriosis incidents.

Abdominal-wall endometriosis occurs as part of extra-pelvic endometriosis. It can be primary, occurring mainly in the umbilicus or groin. Or much more commonly, secondarily within a surgical scar. Symptoms will include abdominal-wall mass, pain, and they may have symptoms of concurrent pelvic endometriosis.

The initial differential also needs to include desmoid tumours and sarcomas. Imaging, such as ultrasound, CT, or MRI, will assist in determining, size, location, and involvement of rectus muscle. Fine-needle aspirate is controversial unless the diagnosis is unclear due to concerns of seeding with malignancy but may be highly useful for desmoid tumours.

Options for management are similar to pelvic endometriosis and include medical or surgical management, with wide local excision being the goal of [unclear] medical management. This may require multi-disciplinary care if mesh or flap placements are required. Care should be individualised to the patient, depending on pain, symptoms, and fertility plans.

We present a case of a 51-year-old with a history of one prior Caesarean section, and a prior panniculectomy and abdominoplasty in 2017. With confirmed abdominal-wall endometriosis from a 13 cm flap removal. She had ongoing pain, and presented to MIS with a growing, palpable, abdominal mass within the place of a prior abdominal-wall endometrioma as shown here.

She initially underwent MRI in 2019 and demonstrated a residual 4 cm abdominal-wall endometrioma in the prior surgical bed. Interval imaging with ultrasound demonstrated growth of the mass, with features consistent with endometriosis, as demonstrated here with the mass entering into the bladder. Of note, in all prior imaging there was no evidence of concurrent pelvic endometriosis or lymphadenopathy.

Initial medical management was undertaken using leuprolide acetate, without addback given prior hormone intolerance. Norethindrone acetate was later added for control of vasomotor symptoms, however there was no volume reduction of the mass. Her original plastic surgeon was re-consulted, and a multi-disciplinary surgical plan was created, including wide local excision with concurrent hysterectomy and bilateral salpingo-oophorectomy, for surgical management of any pelvic disease.

Biopsy of the mass was not done due to lack of prior atypia in the 13 cm specimen in 2017. We started with mapping of the borders of the abdominal-wall mass before pneumoinsufflation. There was no microscopic lymphadenopathy on palpation. Ports were then placed lateral to these borders to avoid breaching the mass. Initial pelvic survey demonstrated significant intra-peritoneal depression of the abdominal-wall endometriosis, without breaching the peritoneum.

Mobility of the uterus was restricted, secondary to the mass, and therefore a complete 360 inspection was limited at the beginning of the case. Bilateral ovaries and fallopian tubes appeared normal, as well as a normal appendix and upper abdomen. Of note, there was no evidence of intra-peritoneal endometriosis in the rest of the pelvis.

With plastic surgery, the incision over her prior abdominoplasty was opened, and the subcutaneous tissue was dissected until the anterior border of the mass was identified. The cranial and caudal borders of the mass were then dissected down, ensuring to take adequate margins of tissue to ensure complete excision. With the lateral borders delineated we could see the mass surface was irregular, with internal cystic-appearing structures, which was concerning for possible malignancy.

We therefore proceeded with frozen section, although the surgical plan of wide local excision would be appropriate regardless of the results. You can see here the internal consistency of the mass is cystic, which was concerning for a clear-cell carcinoma. We can see that this mass is intimately associated with the rectus muscles and pubic synthesis but was not invading these structures.

Further dissection was completed until the mass was removed en bloc. The mass was just over 11 cm in widest diameter and, as shown here, has irregular borders with internal cystic changes. Mesh was then used to reconstruct the abdominal wall, given the size and extent of dissection. The final result demonstrates a smooth abdominal-wall contour.

Frozen sample was inconclusive, but on final pathology there was a clear-cell carcinoma of the abdominal-wall mass within a background of endometriosis. The margins were negative, and the capsule was intact. There was also adenomyosis of the uterus, with benign ovaries and fallopian tubes. She was referred to surgical and gyne oncology.

Endometriosis-associated abdominal-wall cancers are rare and occur in only 1% of all abdominal-wall endometriosis. The most common subtypes are clear-cell and endometrioid carcinoma. A recent systematic review described 73 cases of abdominal-wall endometriosis-related cancers. The median age of presentation was 47, and the median time from initial surgery to cancer presentation was 20 years.

The main symptoms were a combination of abdominal-wall mass and pain. Over 98% of these malignancies have had some type of abdominal surgery, with 83% of these cases occurring within a Caesarean-section scar. Less than 2% of these malignancies were from primary abdominal-wall endometriosis.

In general literature suggests that the recommended initial treatment would be wide local excision with concurrent pelvic surgery to rule out a pelvic source. Lymph-node sampling and omentectomy are variable. Adjuvant treatment adopted from endometriosis-associated ovarian cancer are typically described. This is often an aggressive malignancy, with a 40% five-year survival rate.

Since the majority of these cases are in sites of prior surgery, we could consider malignant transformation of abdominal-wall endometriomas as a potentially preventable result of pelvic surgery. Prevention strategies should therefore be aimed at reducing points of contamination at the abdominal wall.

Since over 80% of these patients have had at least one Caesarean section, risk-reducing strategies include considering avoiding routine exteriorisation of the uterus. Changing instruments before abdominal-wall closure and avoiding contact with the abdominal wall with the hysterotomy. For laparoscopy specimen-removal bags, for endometriomas in particular, should be used in addition to consideration of deflating the abdomen prior to removing trocars.

Malignant transformation of abdominal-wall endometriosis is a rare presentation which typically occurs 20 years from a Caesarean section. Differential diagnoses should be entertained with an appropriate workup performed. Surgical management should always include wide local excision, with exclusion of pelvic organs as the source of malignancy through removal of adnexa and either hysterectomy or endometrial sampling.

Reduction strategies to prevent the seeding of the abdominal wall with endometriosis can be implemented in both Caesarean section and laparoscopy. Many thanks to Dr Justin Yeung and Dr Gwen Hollaar, and to our patient for wanting to educate above all else.