Lipomas are one of the most common benign lesions that occur in the colon and are found during colonoscopies. Only polyps are discovered more often.
Once a diagnosis of lipoma is confirmed, only observation is required. In some cases, however, endoscopic, laparoscopic or surgical removal is necessary.
What is a Lipoma?
Lipomas are round tumors composed of fatty tissue. These tumors are non-cancerous and rarely cause symptoms. They can be found almost anywhere in the digestive tract, but are most commonly found in the bowel walls. Lipomas are most common in people between the ages of 50 and 70, and occur up to twice as frequently in women than in men.
When lipomas in the colon grow unusually large, they may begin to cause symptoms due to their size. These symptoms may include blood in bowel movements, abdominal pain, constipation and intussusception, a condition where one section of the bowel slides inside the section in front of or behind it.
How are Lipomas Diagnosed?
Most lipomas that occur in the gastrointestinal tract cause no symptoms, so they go undetected until they are found during an endoscopic or radiological examination of the bowels. This exam may be prescribed following a positive stool occult blood test, but more often the benign growths are found during a routine preventative colonoscopy.
Even when a lipoma grows unusually large, patients often have vague symptoms, or symptoms which appear and disappear. These intermittent and nonspecific symptoms often delay the patient from seeking medical treatment, and also make the diagnosis more difficult because they could point to a wide variety of gastrointestinal issues.
The most important aspect of diagnosing a lipoma is to distinguish it from a malignant neoplasm — a cancerous growth. In the vast majority of cases, lipomas do not need treatment. Since there is no reason to resect these growths for most people, colon and rectal surgeons look for several signs to ensure a growth is a benign lipoma and not a more harmful growth.
During the colonoscopy, the doctor will look for what is known as the “pillow sign.” They will use endoscopic tools to press on the growth. Lipomas react like a pillow, first indenting then slowly returning to normal after pressure is removed. They may also perform a biopsy of the area. However, gastrointestinal lipomas are covered with normal colon tissue, and the biopsy results usually only demonstrate this tissue.
When Treatment is Required for a Lipoma?
Most lipomas in the gastrointestinal tract need no treatment. Reasons why your doctor may recommend removing a lipoma include:
- To rule out a malignant fatty tumor, or otherwise evaluate the histology
- When they are larger than 2 cm and causing symptoms
- When they are larger than 5 cm, whether currently symptomatic or not, although this is controversial.
Symptoms of lipomas vary from patient to patient. About 23 percent of symptomatic patients suffer from abdominal pain, and 20 percent have rectal bleeding. Other common symptoms include nausea, vomiting, anemia, weight loss and abdominal distention. More serious symptoms such as intussusception and bowel blockage may occur, but are rare.
How are Lipomas Removed?
Lipomas are made of a capsule as well as the yellow fat that fills the capsule. In order to prevent recurrence in the same spot, both the fat and the capsule must be completely removed. This is possible through an endoscopic procedure, a laparoscopic procedure or traditional open surgery. All of these methods can provide an excellent outcome with no possibility of local recurrence as long as the capsule is completely removed.
Advancing technology has made it increasingly safe to excise lipomas in the colon endoscopically, during a colonoscopy. This is considered a non-surgical removal, and is sometimes called “colonoscopic snare” removal. Small symptomatic lipomas are often removed this way, as are growths with a narrow base. EMR, or endoscopic mucosal resection is another method of removing susicious lesions. Larger areas can be removes with this technique. This method is performed by specially trained physicians such as a colon and rectal surgeon.
With larger lipomas or those with a broad base, there is an increased risk of bowel perforation with this procedure, so other options may be explored. Lipomas that are causing hemorrhage or obstruction may also require laparoscopic removal or open surgery.
If there are questions about the histology of the growth, more caution may be taken before removal. Since benign lipomas are mostly harmless, they can simply be scooped out with no worry about the spread of harmful cells. At the same time, the fatty tumors are encapsulated, so there is no spread into the surrounding tissues.
A malignant liposarcoma, on the other hand, would require careful removal as well as the removal of extra tissue around the growth to ensure clear margins showing that the cancer has not spread. For that reason, you may be asked to undergo a biopsy to rule out cancer before the lipoma is removed. If this testing does not exclude the possibility of a malignant growth, laparoscopic or surgical resection of the bowel will probably be used to remove the growth and the surrounding tissue.
In Summation …
There are two primary reasons your doctor may recommend treatment after the discovery of a lipoma-like growth in your colon. Large lipomas may cause serious symptoms, so they may be removed. If you are not suffering from symptoms, your doctor will probably only observe the growth through regular colonoscopies. The exception to this is if testing cannot confirm that the tumor is a benign lipoma and not something more serious.
