Tumors and Tumor-like Conditions

Overview.

Benign lymphoid hyperplasia is a benign condition of the bowel most frequently found in the distal ileum and the colon. These lesions represent patches of lymphoid tissue and can be seen in both adults and children. The precise prevalence in children is unknown, but the entity has been found in up to 30% of symptomatic patients undergoing colonoscopy.

Etiology, Pathophysiology, and Clinical Presentation.

The observation of benign lymphoid hyperplasia in families suggests that genetic or environmental factors could be pertinent. A high prevalence of lymphoid hyperplasia in adults has also been found, possibly related to an enhanced immune response. In children, a number of theories have been proposed, including a local response to infection, immunodeficiency states, and local hypersensitivity reaction. Controversy also exists regarding the association of benign lymphoid hyperplasia with autism spectrum disorder.

Benign lymphoid hyperplasia is usually discovered incidentally either on imaging or at endoscopy. As such, it is almost certainly underrecognized, and its true prevalence is unknown. Visual inspection at colonoscopy will demonstrate multiple raised, closely spaced areas along the bowel wall.

Imaging.

The appearance on imaging studies is that of innumerable small filling defects, mostly uniform in size, at times centrally umbilicated, and most commonly seen on double-contrast imaging of the colon ( Fig. 108.1 ). The lesions typically range in size from 2 to 3 mm and are often too small to be detected on a single-contrast examination. One of the earliest imaging descriptions stressed the need to distinguish lymphoid hyperplasia from true polyps, citing instances in which colectomies were performed because the benign nature of these lesions was not recognized. The characteristic pattern of innumerable small, uniform lesions also should be distinguished from benign lymphoid polyps, which are more common in adults and can become large and pedunculated.

Treatment.

Lymphoid hyperplasia itself requires no specific treatment. If it is associated with another condition, then that condition would be treated accordingly .

Overview.

A number of vascular lesions and vascular tumors can arise within the colon. Although rare in children, they usually have specific clinical and imaging findings that can allow for a specific diagnosis. Some vascular lesions will be found incidentally while others present as lower gastrointestinal (GI) tract bleeding.

Etiology, Pathophysiology, and Clinical Presentation.

Vascular lesions of the colon represent a wide array of conditions. Colonic varices (particularly in the rectal region) appear as mural lesions and typically are associated with portal hypertension, providing a collateral pathway between the portomesenteric and the systemic venous systems. This collateral pathway has been reported to occur in nearly one-third of children with portal hypertension, in whom rectal bleeding is seen in 7%.

Other colonic vascular lesions that cause lower GI bleeding include venous malformations, arteriovenous malformations, angiodysplasia, telangiectasias, and hemangiomas. Most vascular malformations of the pediatric GI tract are vascular malformations of the cavernous type. These can be components of syndromes of anomalous vascular development such as Klippel–Trenaunay syndrome and blue rubber bleb nevus syndrome.

Because vascular lesions of the colon tend to come to light when they are symptomatic, the true incidence is unknown, but they are believed to be rare in children. The presentation can be that of lower GI bleeding or iron deficiency anemia. It should be noted that hemangiomas, though discussed here, fall under the category of vascular tumors of the GI tract and are associated with cutaneous hemangiomas in up to 50% of cases.

Imaging.

The lesions are difficult to resolve with most imaging modalities, but imaging with CT in the early arterial phase after contrast injection can demonstrate these lesions. Involved bowel will show intense enhancement ( Fig. 108.2 ), and occasionally abnormal supplying arteries or draining veins are visible. In a minority of cases with bleeding, active extravasation can be seen.

Treatment.

Much like vascular lesions elsewhere in the GI tract and indeed elsewhere in the body, the treatment depends on the specific lesion, its location, the degree and extent of involvement, and the clinical status of the patient. These lesions can be treated medically or surgically, embolized angiographically, or sclerosed endoscopically.

Overview.

Juvenile or hamartomatous polyps are the most common intestinal tumors in childhood, with a prevalence of 1% to 3%. They may be single or multiple, and most are found in the sigmoid colon and rectum, but they can arise anywhere along the GI tract.

Etiology, Pathophysiology, and Clinical Presentation.

Histologically these lesions appear as mucus-filled glands, and they might be related to blocked, hyperplastic mucus glands. A dense infiltrate of inflammatory cells suggests an inflammatory inciting event, and thus the synonymous term “inflammatory polyp.” However, the underlying etiology of these isolated polyps remains to be determined.

Most patients present in the first decade, typically between 2 and 5 years of age. The most common presenting symptom is painless, bright-red rectal bleeding. Pain is associated with the rare complication of colocolic intussusception. Some children present with iron deficiency anemia and others with a prolapsing mass, which can be mistaken for rectal prolapse.

Imaging.

In the past, investigation for colonic neoplasms such as the juvenile polyp in a child with rectal bleeding often included a double-contrast enema. On such an examination, the lesions are typically smooth, can be sessile or pedunculated, and measure 3 cm or less. Currently the diagnosis is frequently made endoscopically or on cross-sectional imaging, with the lesions appearing as nonspecific intraluminal masses ( Fig. 108.3 ).

Treatment.

Because these solitary lesions carry no increased risk of malignancy, the treatment is polypectomy alone. Most commonly, a polypectomy is performed with snare resection during a colonoscopy. Anemia is treated with iron supplementation or transfusion if necessary. With resection of the polyp, the blood loss should cease. If multiple polyps are present or a family history of juvenile polyps is uncovered, then the patient should be evaluated for the juvenile polyposis syndrome (JPS), discussed later.

Overview.

First described in the literature in 1964, JPS is an autosomal-dominant condition characterized by a multiplicity of GI hamartomatous polyps. It is the most common of the hamartomatous syndromes.