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Clinical Characteristics

Patients with a helminthoma usually have vague, non-specific complaints, often for periods as short as 2 to 5 days. Others, especially children, may suffer intermittent attacks of colic for 2 or 3 weeks, simulating intussusception. Some patients complain of abdominal pain localized to the site of the helminthoma, usually in the right lower quadrant, less often in the left iliac fossa or elsewhere in the abdomen. There may be anorexia, nausea, vomiting and low grade fever. If the nodule ruptures inward, there may be bloody diarrhea and dehydration. The white blood cell count is elevated, and some patients have moderate eosinophilia. If the nodule ruptures outwards, there will be peritonitis.

On clinical examination there is abdominal guarding and tenderness and often an easily palpable, tender mass. The tumor is usually smooth, well localized in some patients, more diffuse in others. The clinical diagnoses are likely to be an appendiceal or pericecal abscess, diverticulitis, amebiasis with an ameboma, intussusception, a pelvic abscess, or malignancy. Rarely, helminthomas are multiple. In acute cases in childhood, there may be perforation of the cecum anteriorly with an abscess extending to the abdominal wall, which may be the presenting finding. In some parts of West Africa, it is well known to villagers, who describe it as having "a turtle in the belly". Local heat is applied until it ruptures.

Radiological Diagnosis

The essential finding is a mass, which may be small or large, in the wall of the bowel. It seldom encircles the lumen, but the intramural mass causes eccentric narrowing which may be mistaken for extrinsic pressure. It is commonly localized in or adjacent to the wall of the cecum or ascending colon (Fig. 18.2).

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Fig. 18.2 A-D. Helminthoma: four examples of this granulomatous tumor caused by a worm burrowing into the wall of the cecum. The radiographic appearance must be distinguished from amebiasis, tuberculosis, and carcinoma. It is often impossible to identify the worm in the pathological specimen.

It is best demonstrated by a barium enema with air contrast or by ultrasonography or CT. The mucosa is usually intact and shows no significant abnormality apart from stretching over the underlying intramural mass. The edges of the mass are usually sharply defined and biconvex, as expected in an intramural lesion (Fig. 18.3). Very rarely barium may fill a small perforation following the route of the worm (Fig. 18.3B), but there is usually too much edema and swelling to demonstrate this. Contraction of the entire cecum, as occurs in amebiasis or tuberculosis, or involvement of the whole bowel circumference is unlikely, nor should the bowel lumen be invaded; instead, it is sharply distorted. As the tumor enlarges and spreads outwards, the bowel will become fixed.

A helminthoma which is found unexpectedly in the bowel by the radiologist or surgeon is likely to be small and more mobile. The intervening bowel wall and the mucosa will be normal. It will then be even more difficult to make the correct diagnosis.

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Fig. 18.3 (A) A helminthoma in the proximal sigmoid colon has the radiographic appearance of an intramural or wall lesion but may be mistaken for an ameboma or carcinoma. Radiological differentation may not be possible. (Courtesy of Dr. J.M. Welchman, Kampala) (B) Another helminthoma in the sigmoid colon showing the beginning of the perforating track from the bowel lumen outwards.

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