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A female, 59 year-old patient complaining of colic-like abdominal pain and mild enterorrhagia for some months. No abnormal finding was observed at physical examination and laboratory tests. Colonoscopy demonstrated the presence of an expansile occlusive luminal lesion in the ascending colon. The patient was referred for radiological staging and submitted to contrast-enhanced abdominal computed tomography (Figure 1).

Figure 1

Axial CT section (A) and coronal reformation (B).

Image description

. Axial CT section (A) and coronal reformation (B) showing a predominantly lipomatous tumor with fat density in the transverse colon (arrows), with bosselated contour, measuring about 9 cm in its greater cross-sectional diameter, and signs of ileocolic intussusception.

Diagnosis: Giant colonic lipoma.

COMMENTS

The Brazilian radiological literature has recently highlighted the relevance of imaging methods in the improvement of the diagnosis of digestive system conditions(.

Colonic lipoma is a rare benign tumor in spite of being the most common non-epithelial (mesenchymal) neoplasia in the gastrointestinal tract. Generally, it is located in the submucosa and, in rare cases, in the subserous membrane( and may have a lobulated aspect. This tumor is more commonly found in women (66,7%)( between the fifth and sixth decades of life, and is asymptomatic in most cases. However, a tumor > 2-3 cm may generate normally nonspecific and long-lasting symptoms such as abdominal pain, blood in stools and change in bowel habits(. Larger tumors may present symptoms of bowel obstruction with colonic intussusception(. Spontaneous elimination of lipomas has also been reported(.

Studies demonstrate that approximately 46% of bowel lipomas are incidentally found in surgical specimens removed for other conditions(, and the ascending colon is the most common site of involvement(.

Imaging studies can be useful in the preoperative diagnosis, but generally the definitive diagnosis is made with basis on the analysis of the surgical specimen( (Figure 2). However, the finding of macroscopic fat at computed tomography or magnetic resonance imaging narrows the differential diagnosis in these cases(.

Figure 2

Surgical specimen showing a lipomatous tumor in the transverse colon (arrows).

Barium enema demonstrates luminal filling failure, but such finding is nonspecific and may be observed in other types of colonic neoplasias(.

Unenhanced nodules or parietal mass with fat density (-40 to -120 Hounsfield units), as described in the present case, represent a useful tomographic finding in the diagnosis. In cases of association with intussusception, the diagnosis may be more difficult because of the presence of necrotic foci or infarct( and, in many cases, the differential diagnosis with other lesions such as adenocarcinomas, lymphomas and metastases( cannot be reliably be established.

The treatment varies with the location, symptoms and size of the lipoma. Lesions < 2 cm may be endoscopically resected with the aid of ultrasonography in order to reduce the risk of perforation. The great majority of authors recommend surgical treatment for lesions > 2 cm, and the surgical options include lesion resection, partial colectomy and hemicolectomy(.

Main differential diagnoses include adenoma, adenocarcinoma, lymphoma, neuroendocrine tumors, fibroma, leiomyoma and hamartoma(.

Although rare, colonic lipomas should be considered in the differential diagnosis of large bowel tumors. An accurate diagnosis is hardly made preoperatively and many times the lesion may be confused with adenomatous polyps or carcinoma. The surgical approach is the treatment of choice for colonic lipoma, varying with the lesion size and location, and with the presence or not of complications(.