Abdominal fibromatosis is a condition characterised by benign soft tissue tumours on the abdominal wall. Although they are not malignant and cannot spread to other parts of the body, they can grow rather aggressively and invade abdominal organs. They also frequently recur locally and have a high rate of morbidity and mortality. Abdominal fibromatosis accounts for 0.03% of all neoplasms and 3% of all soft tissue tumours.
Abdominal fibromatosis is also referred to as desmoid tumour and aggressive fibromatosis due to its tendency to infiltrate even through deep skeletal muscles, compressing nerves and blood vessels in the process. The word “desmoid” is taken from the Greek word “desmos”, which means tendon-like. Thus, the condition shares some characteristics with sarcomas, such as adenocarcinoma, leiomyosarcoma, and lipoma.
Aggressive abdominal fibromatosis tumours can also attach to bones and eventually cause them to erode. Hence, although they do not metastasise (spread), they can still cause severe medical problems and negative effects on the patient’s general health condition simply due to their local growth and invasion.
The nature of abdominal fibromatosis, its effects, as well as potential treatments are impacted by the tumours’ specific location in the abdomen. Based on their location, the tumours are identified as:
Abdominal wall fibromatosis – Tumours that form on the walls of the abdomen
Extra-abdominal fibromatosis – Tumours that form outside the abdomen or abdominal wall
Intra-abdominal fibromatosis – Tumours that form within the abdomen in mesenteric, pelvic, or retroperitoneal locations
The condition also comes in various subtypes, including:
Abdominal fibromatosis is known to be caused by mutations in the APC or B-catenin genes, or both. However, the condition can also develop sporadically in patients with no history of genetic disease. Some studies show that sporadic growth of abdominal fibromatosis may be due to repeated trauma, including surgical trauma, to the affected body part, with oestrogen playing a role in the formation of the tumour. Thus, patients who have had previous abdominal surgery face a higher risk of developing abdominal fibromatosis.
Studies also show that 2% of desmoid tumours affect patients suffering from familial adenomatous polyposis (FAP) or its various forms, such as Gardner’s syndrome. In fact, for some patients, desmoid tumours are the first manifestation of their underlying condition. The tumours usually form when the patient is between the ages of 28 and 31 years old, but may also occur at any age. The risk of desmoid tumour growth further increases due to a previous surgery, with most tumours forming around 4.6 years after a surgical procedure. In many patients with FAP, the tumour is the leading cause of mortality.
Patients who have had previous abdominal surgery or suffer from FAP face a greater risk of developing intra-abdominal fibromatosis.
Due to the growth patterns of intra-abdominal fibromatosis and extra-abdominal fibromatosis, they can cause the following health problems:
Obstructed abdominal organs
Obstructed mesenteric vessels
These may not always be accompanied with pain. In fact, only one-third of abdominal fibromatosis cause abdominal pain. This makes them quite challenging to detect and diagnose.
When left to proliferate, the tumours can compress vital abdominal organs and cause serious, life-threatening problems. This is true for all desmoid tumours, regardless of their location. In one such case, a mesenteric desmoid tumour led to an acute pulmonary embolism and eventually resulted in acute myocardial infarction when the tumour compressed the inferior vena cava.
Patients who experience the above symptoms should see their general physician or family doctor for a diagnosis. Those diagnosed with abdominal fibromatosis are referred to tumour specialists as well as surgeons who specialise in the treatment of sarcoma. The patient’s medical care team may also include oncologists (cancer treatment specialists), gastrointestinal surgeons, and radiation specialists.
The primary treatment option for patients with abdominal fibromatosis is surgical resection for the removal of the tumour along with a wide margin of healthy tissue around it. Less than 5% of surgically excised tumours recur. Abdominal wall tumours as well as extra-abdominal desmoid fibromatosis are relatively easy to remove during surgery. Intra-abdominal tumours, on the other hand, are more difficult and sometimes, even impossible to remove. The condition is further aggravated by the presence of an FAP diagnosis, which almost completely rules out surgery due to high rates of recurrence of desmoid tumours in FAP patients. In such cases, the patients can either undergo surgery for the removal of the intestines or other alternative non-surgical multi-disciplinary treatments.
Surgery is also not immediately recommended upon diagnosis. Nowadays, most doctors advise patients to undergo a period of watchful waiting, during which the tumours are closely observed for signs of growth and proliferation. This approach is backed by studies that show how some desmoid tumours do not grow or sometimes even regress spontaneously. Modern imaging methods such as computed tomography (CT) and magnetic resonance imaging (MRI) scans make the process of following the progress of abdominal fibromatosis easier and more effective.
If the tumours show signs of growth and local invasion that may put nearby organs at risk, then surgery becomes necessary.
Some patients are also prescribed with systemic therapy, such as radiation therapy, hormonal therapy, chemotherapy, targeted therapy, and the use of non-steroidal anti-inflammatory drugs. The use of hormonal therapy is founded on studies that show a link between desmoid tumour growth and oestrogen; thus, patients are given anti-oestrogens such as Tamoxifen.
Most patients who undergo surgical resection also require these therapies as follow-up treatments, and in many cases, treatment is successful with a low recurrence rate.
Newer, experimental treatments are also available, such as the use of Gleevec and Nexavar, which are yielding promising results so far.
The most ideal treatment option is determined based on the tumour’s size, location, potential risks and benefits of surgery, and the patient’s preference.
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Overhaus M, Decker P, Fischer HP, Textor HJ, Hirner A. “Desmoid tumours of the abdominal wall: A case report.” World J Surg Oncol. 2003; 1:11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC169179/
Palladino E, Nsenda J, Siboni R, Lechner C. “A giant mesenteric desmoid tumour revealed by acute pulmonary embolism due to compression of the inferior vena cava.” Am J Case Rep. 2014; 15:374-377. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4159246/