What are the other Names for this Condition? (Also known as/Synonyms)

• AML of Colon
• Angiomyolipoma of Large Intestine
• Colonic Angiomyolipoma

What is Angiomyolipoma of Colon? (Definition/Background Information)

• An angiomyolipoma (AML) is a benign tumor that is a mixture of blood vessels (angio-), smooth muscles (myo-), and fat (or lipoma). The tumor is seen among a wide age range of adults and can occur at various locations in the body. But, the most common location is the kidney
• Angiomyolipoma of Colon (or Colonic Angiomyolipoma) is a very uncommon extrarenal AML that may be present in the large intestine or colon. Currently, almost all the cases have been reported in adult men
• Angiomyolipoma can be associated with a syndrome (tuberous sclerosis) in some cases, termed syndromic angiomyolipoma; or in a majority of cases, it may not be associated with a genetic disorder, when it is termed non-syndromic angiomyolipoma. An association of Angiomyolipoma of Colon with tuberous sclerosis has been rarely reported
• Many angiomyolipomas are found incidentally while examining the individual for other medical conditions. The signs and symptoms depend upon the size of the tumors. Large tumors are known to cause abdominal discomfort, bloating, and irregular bowel movements
• Typically, a surgical excision and removal of Angiomyolipoma of Colon may be undertaken. Recently, newer therapy involving FDA-approved medications may also be considered
• The prognosis of Colonic Angiomyolipoma is generally excellent with its complete removal, since it is a benign tumor. However, the prognosis also depends upon a set of factors that includes the severity of the signs and symptoms, age and overall health of the individual, response to treatment, and its association with tuberous sclerosis

Who gets Angiomyolipoma of Colon? (Age and Sex Distribution)

• Angiomyolipoma of Colon has been predominantly observed in middle-aged men. It has also been observed in much older men
• The tumor may also affect females (adult women)
• No ethnic or racial preference is seen
• Angiomyolipoma of Colon is a very rare tumor and only less than 10 cases have been reported in the medical literature

What are the Risk Factors for Angiomyolipoma of Colon? (Predisposing Factors)

Currently, no specific risk factors have been noted for Angiomyolipomas of Colon. The risk factors for angiomyolipoma, in general, may include the following:

• Tuberous sclerosis (TS) is a risk factor for angiomyolipoma, and hence, a family history of TS can increase the risk. Tuberous sclerosis complex is an inherited genetic disorder that can cause the formation of other tumor types, such as astrocytomas, rhabdomyomas, phakomas, oncocytomas, and angiofibromas, at various body locations
• In general, AML can also be associated with other syndromes/disorders including:
  • von Recklinghausen disease (neurofibromatosis type I)
  • von Hippel-Lindau disease
  • Sturge-Weber syndrome
  • Autosomal dominant polycystic kidney disease
• Some reports indicate that events causing an hormonal imbalance in the body, such as puberty and pregnancy in women, may be a risk factor

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Angiomyolipoma of Colon? (Etiology)

The exact cause and mechanism of Angiomyolipoma of Colon formation, in a majority of cases, is unknown. Solitary tumors are believed to be the result of sporadic mutations on TSC1 or TSC2 genes, implying that they do not have a preceding family history of the condition.

• Research has shown that the tumors arise from cells called perivascular epithelioid cells (PEC), which surrounds the blood vessels. Hence, angiomyolipoma (AML) is a type of a tumor known as a PEComa
• Multiple angiomyolipomas are known to occur in a background of tuberous sclerosis (TS), which is a genetic condition. It may also occur when there is a positive family history of the condition. In the case of Colonic Angiomyolipoma, an association with TS has not been evidently noted
• In general, syndromic AML is also associated with other genetic disorders such as von Recklinghausen disease, von Hippel-Lindau disease, Sturge-Weber syndrome, and autosomal dominant polycystic kidney disease
• Some research indicates that hormonal influence may play a role in AML formation for the following reasons:
  • The tumor is more often seen in women
  • It grows larger during pregnancy
  • The onset can be after puberty
  • And high progesterone receptor activity is present on microscopic examination

What are the Signs and Symptoms of Angiomyolipoma of Colon?

The signs and symptoms of Angiomyolipoma of Colon may include the following:

• Most tumors are small-sized and may not exhibit any signs and symptoms
• Large tumors (size over 4 cm) can compress the surrounding structures or organs and give the sensation of an abdominal mass
• Colonic tumors are known to appear like a polyp (some are pedunculated)
• Abdominal pain and discomfort
• Rarely, blood in stool resulting in anemia
• Irregular bowel movements; diarrhea or constipation
• Abdominal distension/bloating/enlargement
• Intestinal obstruction due to large tumors may occur
• Bleeding can occur within large tumors; hemorrhage within the tumors can lead to tissue death (or infarction)
• In sporadic cases (when not associated with tuberous sclerosis), angiomyolipoma is usually single. Often with sporadic tumors, they tend to be larger and so signs and symptoms may be observed
• With a syndrome or genetic disorder, multiple tumors may be noted

How is Angiomyolipoma of Colon Diagnosed?

A diagnosis of Angiomyolipoma of Colon may involve the following tests and procedures:

• Complete physical exam with evaluation of medical history
• Ultrasound scan of the abdomen: It is a noninvasive procedure that uses high frequency sound waves to produce real-time images
• Abdominal and pelvic CT scan: It is a noninvasive procedure that provides more details of soft tissues, blood vessels, and internal organs
• Stool sample analysis
• Screening colonoscopy: A colonoscopy is a test that allows the physician to look at the inner lining of the colon and rectum. A typical colonoscopy involves using a thin, flexible tube (called a colonoscope), with an attached video camera, to view the colon and rectum
• Lower gastrointestinal series, which are a combination of analysis methods, combining X-rays and barium to visualize the intestinal region
• Vascular angiographic studies of the tumor
• Exploratory laparoscopy (diagnostic laparoscopy) may be required, if gastrointestinal symptoms are present. In this procedure, the abdomen is examined using a minimally-invasive technique, and a tissue biopsy and tissue for culture obtained

Although the above modalities can be used to make an initial diagnosis, a tissue biopsy of the tumor is necessary to make a definitive diagnosis to begin treatment. The tissue for diagnosis can be procured in multiple different ways which include:

• Endoscopic fine needle aspiration (FNA) biopsy of the tumor: An endoscopic FNA biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor. Hence, a FNA biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy is preferred
• Core biopsy of the tumor
• Open biopsy of the tumor

Tissue biopsy:

• A tissue biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
• Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
• The tumors may have varying proportions of blood vessels, smooth muscle, and fat cells, when examined by a pathologist under a microscope
• Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies to assist in the diagnosis

Note: A differential diagnosis, to eliminate other tumor types is considered, before arriving at a conclusion.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Angiomyolipoma of Colon?

The complications of Angiomyolipoma of Colon are dependent upon the size of the tumor and may include:

• Large tumor masses may get secondarily infected with bacteria or fungus
• Stress and anxiety due to fear of cancer of the intestine
• Polypoid tumors may undergo mechanical injury, such as torsion or twisting, which can result in excruciating pain
• Severe bleeding from the gastrointestinal tract
• Damage to the muscles, vital nerves, and blood vessels, during surgery
• Post-surgical infection at the wound site is a potential complication
• Research has not conclusively proven that angiomyolipoma can turn malignant. Although, some cases of sarcoma developing from AML (not associated with tuberous sclerosis) have been noted

How is Angiomyolipoma of Colon Treated?

The treatment measures for Angiomyolipoma of Colon may include the following:

• Majority of asymptomatic tumors are not surgically removed: The healthcare provider may recommend a ‘wait and watch’ approach for small-sized tumors presenting mild signs and symptoms, after a diagnosis of angiomyolipoma is established
• Pain medications for AML of Large Intestine causing pain
• Surgical intervention with complete excision can result in a complete cure. It can also help reduce the chances of tumor recurrence
  • Small tumors may be removed during a colonoscopy and sent for testing, in order to ensure that they are non-malignant or harmless
  • Partial colectomy or bowel resection, where the damaged portion of the colon is surgically removed
  • Tumor embolization (performed on a case-by-case basis) is a possible treatment option. Here the blood supply to the tumor is blocked resulting in its shrinkage or death
• Newer medical treatments; recently FDA-approved medications may also be used
• Prompt diagnosis and treatment of any severe GI tract bleeding due to the tumor
• Treatment of the underlying or associated conditions, if any
• Post-operative care is important: A minimum activity level is ensured, until the surgical wound heals
• Follow-up care with regular screening may be recommended by the healthcare provider

How can Angiomyolipoma of Colon be Prevented?

Current medical research has not established a method of preventing both syndromic and non-syndromic forms of Angiomyolipoma of Colon. However, in case it is associated with genetic disorders, such as tuberous sclerosis, then the following may be considered:

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders such as tuberous sclerosis
• Regular medical screening at periodic intervals with tests and physical examinations are strongly recommended

What is the Prognosis of Angiomyolipoma of Colon (Outcomes/Resolutions)

• The prognosis of Angiomyolipoma of Colon depends upon the severity of the signs and symptoms. It also depends upon the overall health of the individual, association with tuberous sclerosis, and response to therapy
• Typically, individuals with small-sized tumors have a better prognosis than those with larger-sized tumors (over 4 cm in size). Also, those with non-syndromic (sporadic) tumors have a comparatively better prognosis than individuals with tumors that are seen in association with a genetic disorder (syndromic)
• In most cases, the prognosis of small-sized solitary tumors is excellent with surgical intervention or appropriate treatment, since these are benign tumors

Additional and Relevant Useful Information for Angiomyolipoma of Colon:

Angiomyolipoma can occur at various locations in the body, such as the soft tissue, skin, fallopian tube, spermatic cord, penis, liver, and lung.