Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Colonic Vascular Lesions


Etiology

Vascular lesions of the colon are an important medical problem and have now been recognized as a significant cause of gastrointestinal bleeding. They can be solitary or multifocal, benign or malignant, or associated with a syndrome or systemic dis­order. There are three main groups: vascular malformations, neoplastic lesions, and non-neoplastic lesions ( Figure 32-1 ). Vascular malformations can be broadly classified into arterial, venous, and arteriovenous types. Neoplastic lesions include hemangiomas, hemangioendotheliomas, and angiosarcomas. Non-neoplastic lesions can be further divided into inflammatory lesions (e.g., vasculitis) and obstructive lesions (e.g., ischemic colitis). Few systemic conditions and syndromes manifest with vascular lesions, such as colonic varices in portal hypertension or vasculitis in systemic lupus erythematosus, polyarteritis nodosa, Ehlers-Danlos syndrome, Osler-Weber-Rendu disease, Marfan syndrome, and systemic sclerosis. This chapter focuses on vascular lesions that cause gastrointestinal bleeding and that are representative of the spectrum of vascular lesions of the gastrointestinal tract.

Figure 32-1, Algorithm for colonic vascular lesions.

Prevalence and Epidemiology

The prevalence is related to the cause and age of the patient. The prevalence of angiodysplasia is 0.8% in healthy patients older than 50 years who are undergoing screening colonoscopy. These lesions characteristically appear in the right colon and cecum in older patients, although they may be found anywhere in the lower gastrointestinal tract, may be multiple, and can occur in younger patients. Dieulafoy's lesion involving the colon is rare and more frequently affects the stomach. It is twice as common in men as in women and manifests at a mean age of 52 years. Hemangiomas are benign vascular tumors that can be found throughout the gastrointestinal tract, often in the rectum or colon. The incidence of gastrointestinal hemangioma is reported as 0.3%, and these tumors account for 5% to 10% of all benign intestinal tumors. In some populations these lesions are multiple and associated with skin lesions, such as the blue rubber bleb nevus syndrome with purple-blue cutaneous hemangiomas or the Klippel-Trenaunay syndrome with port-wine–colored cutaneous hemangiomas, hemihypertrophy, and varicose veins. Rare vascular malignant neoplasms of the gastrointestinal tract include angiosarcomas, hemangiopericytomas, and hemangioendotheliomas. The incidence of these lesions is highly variable. Telangiectases are similar to angiodysplasias but occur in all the layers of the bowel wall, are usually congenital, and often occur in other organ systems. Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease) is an autosomal dominant disorder with telangiectases involving the lips; mucous membranes, especially in the mouth and nose; gastrointestinal tract, especially the stomach and small bowel; liver; lung; retina; and central nervous system.

Clinical Presentation

Although many vascular lesions are asymptomatic, those that manifest with bleeding require expeditious localization and control. These lesions may be responsible for severe, acute, and overt bleeding or alternatively can cause chronic or occult bleeding. Some of these lesions are difficult to localize on cross-sectional imaging and colonoscopy and necessitate use of more invasive modalities such as angiography. Although the clinical presentation, age of the patient, and other epidemiologic factors may indicate a particular type of colonic vascular lesion, endoscopy with biopsy and visceral angiography are critical in establishing the correct diagnosis.

Pathophysiology and Pathology

Pathologic processes of vascular lesions involving the colon depends on the underlying cause, which can be vascular, neoplastic, or non-neoplastic in origin.

Angiodysplasia

These lesions are acquired vascular ectasias, possibly caused by chronic, low-grade colonic obstruction. Histologic identification is difficult unless special techniques are used. Microscopically, angiodysplasias are composed of clusters of dilated, tortuous, thin-walled veins, venules, and capillaries localized in the colonic mucosa and submucosa.

Dieulafoy's Lesion

Dieulafoy's lesion belongs to an arterial type of vascular abnormality with abnormally large (caliber-persistent) submucosal end-arteries; in some instances, there is a small, overlying mucosal defect.

Congenital Arteriovenous Malformations

Histologically, arteriovenous malformations are persistent congenital communication between arteries and veins located in the submucosa. Characteristically, arterialization of the veins is seen. The veins are tortuous and dilated, having thick walls with smooth muscle hypertrophy and intimal thickening.

Hemangioma

Hemangioma is the second most common vascular lesion of colon and may be solitary or may be multiple in patients with multisystem involvement. Histologically, hemangiomas can be divided into cavernous, capillary, and mixed. Cavernous hemangiomas are composed of large, dilated spaces filled with blood and are covered with a thin wall of abnormal vessels. Capillary hemangiomas consist of conglomerates of small, thin-walled vessels.

Imaging

Because the clinical presentation and manifestations of patients with colonic vascular lesions in the form of lower gastrointestinal bleeding overlap with those of other colonic diseases, a precise identification of cause is possible only with a high degree of suspicion and by using different imaging modalities. A precise knowledge of clinical background with imaging findings can help narrow the differential diagnosis. Although there is no specific algorithm, the information presented in Box 32-1 and Table 32-1 should be kept in mind when there is a high index of suspicion of a vascular lesion.

Box 32-1
Clinical Factors in Differentiating Colonic Vascular Lesions

  • Age

    • Elderly

      • Angiodysplasia

      • Dieulafoy's lesion

      • Ischemic colitis

    • Children

      • Hemangiomas

      • Hereditary hemorrhagic telangiectasia

  • Location of Involvement

    • Angiodysplasia: Cecum and proximal ascending colon

    • Hemangiomas: Predilection for rectosigmoid region

  • Multifocal Involvement

    • Hemangioma

TABLE 32-1
General Information and Diagnostic Modalities
Angiodysplasia Hemangioma Dieulafoy's Lesion
Age Older than 50 years Younger age group No specific age distribution
Diagnostic modalities Endoscopy, catheter angiography, or CT angiography CT and endoscopy Endoscopy and angiography
Radiographs N/A Phleboliths can be seen on radiographs. N/A
CT/CTA Findings Ectatic, dilated vessels in the wall of colon, an early filling vein, and an enlarged ileocolic artery Enhancing lesion with phleboliths N/A
MRI findings N/A Thickened colon wall with high signal intensity on T2-weighted imaging N/A
Colonoscopy Lesions are flat, 2-5 mm in diameter, and red. Elevated blue nodular lesions or dilated vessels Caliber-persistent artery protruding from the mucosa
CT , Computed tomography; CTA , CT angiography; MRI , magnetic resonance imaging; N/A , not applicable.

Angiodysplasia

Angiodysplasia or vascular ectasia is the most common vascular malformation of the gastrointestinal tract in the elderly and one of the major causes of lower gastrointestinal bleeding. Accurate diagnosis may require a combination of diagnostic techniques, such as angiography, nuclear scanning, and colonoscopy.

Barium Studies

Because the lesions of angiodysplasia are small in diameter and do not distort the mucosa, double-contrast barium enema studies are of no value in the diagnosis of angiodysplasia. This technique is useful, however, to rule out other causes of gastrointestinal bleeding, such as neoplastic lesions.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts