Tumors and Tumorlike Conditions

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Chapter 109

Tumors and Tumorlike Conditions

Tumors and tumorlike conditions affecting the colon in children can be divided into several categories. For the purpose of this chapter, we will discuss benign lymphoid hyperplasia, vascular lesions of the colon, and neoplasms. Several neoplasms arise in patients with genetic disorders, and in those cases, we have attempted to provide a brief description of the disorder. Although these colonic lesions, particularly the neoplastic ones, tend to be rare in children, it is incumbent on the radiologist to be familiar with them to be able to provide a thoughtful and thorough consultation with respect to the imaging findings.

Nonneoplastic Lesions

Benign Lymphoid Hyperplasia

Etiology: A number of possible causes have been postulated. The observation of benign lymphoid hyperplasia in families suggests that genetic or environmental factors could be pertinent.2 A recent study by Krauss et al.3 found that the prevalence of lymphoid hyperplasia at colonoscopy also is high in adults, and they postulated that it may relate 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 and the autism spectrum disorder.4

Imaging: The appearance on imaging studies is that of innumerable small filling defects, mostly uniform in size, at times umbilicated, and most commonly seen on double-contrast imaging of the colon (Fig. 109-1). These lesions are often too small to be detected on a single-contrast examination. One of the earliest imaging descriptions stressed their benign nature and the need to distinguish the lesion from true polyps,5 citing instances in which colectomies were performed because the benign nature of these lesions was not recognized. This pattern of innumerable small lesions (often in the range of 2 to 3 mm) also should be distinguished from benign lymphoid polyps, which are more common in adults and can become fairly large and pedunculated.6

Vascular Lesions

Etiology: Vascular lesions of the colon represent a wide array of conditions. The etiology is known for some lesions and remains unknown for others. Colonic varices (particularly in the rectal region) can be seen as mural lesions and typically are seen 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 that group of patients, significant rectal bleeding was seen in 7%.7

Other vascular lesions also can result in lower GI bleeding. Venous malformations, arteriovenous malformations, angiodysplasia, telangiectasias, and hemangiomas all have been described in the colon in children but are rare.8 Their etiology is not well understood.

Imaging: The lesions are difficult to resolve with most imaging modalities. Multidetector computed tomography (CT) with imaging in the early arterial phase after contrast injection can demonstrate these lesions. Involved bowel will show intense enhancement (Fig. 109-2). Some patients will have abnormal supplying arteries or draining veins visible on CT. In a minority of cases with bleeding, active extravasation can be visualized.9

Neoplastic Lesions

Neoplasms of the colon are rare in children. Most are benign juvenile polyps. Polyps associated with the hereditary polyposis syndromes are quite rare, and there is often a known family history. Primary malignancies arising from the colon and metastatic disease to the colon are rarer still. These three groups will constitute the remainder of this chapter.

In the past, the double-contrast barium enema has been the study of choice in the investigation of colonic neoplasms. However, more recently, ultrasound, CT, and magnetic resonance imaging (MRI) increasingly have been used. Often these modalities are used in the initial stages of the investigation, but the final diagnosis is established after endoscopy, snare resection, and/or surgical intervention.

Juvenile Polyps

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, these lesions are typically smooth and can be sessile or pedunculated; most measure 3 cm or less. Currently the diagnosis is more frequently made endoscopically or on cross-sectional imaging, in which the lesions appear as nonspecific intraluminal masses (Fig. 109-3).

Polyposis Syndromes

Although the inherited polyposis syndromes are rare, they have the potential to cause serious morbidity and mortality within affected families. A proper understanding of the various conditions is important for the primary clinician and consultant. Genetic screening and initiation of a surveillance plan is mandatory. Surveillance should include the GI tract as well as extraintestinal sites of potential disease.13

Syndromes Associated with Juvenile or Hamartomatous Polyps

Juvenile Polyposis Syndrome

Overview: First described in the literature in 1964,14 JPS is an autosomal-dominant condition that is characterized by a multiplicity of GI hamartomatous polyps. It is the most common of the hamartomatous syndromes.

Clinical Presentation: From a clinical standpoint, the disease should be considered in any patient with five or more juvenile polyps in the colon, extracolonic juvenile polyps, or with any number of polyps when associated with a positive family history.16 The clinical presentation can be more variable than in the patient with nonsyndromic juvenile polyps. In addition to rectal bleeding, anemia, and intussusception, patients with JPS in whom there is involvement of a large segment of the GI tract can present with failure to thrive, malabsorption, or hypoalbuminemia. Associated congenital anomalies include hydrocephalus and hypertelorism. Small series have described JPS in association with other conditions, including hereditary hemorrhagic telangiectasia.17

Treatment: Patients with JPS have an increased risk of colonic malignancy that is reported to be as high as 50% on the basis of family studies.18 Screening of these children can be done with a combination of endoscopy, various imaging modalities, and capsule endoscopy. Polyps typically are removed via snare polypectomy.

Cowden Syndrome

Overview: Cowden syndrome is a rare autosomal-dominant syndrome with an estimated prevalence of 1 : 200,000 individuals.19 Features include hamartomatous polyps of the GI tract, hamartomatous lesions of the skin, hamartomas of other solid organs, and neoplasms of the breast, thyroid, and endometrium.19 GI tract polyps arising in these patients include inflammatory, hyperplastic, lipomatous, and even adenomatous lesions.