Angiolipoma is a benign tumor, commonly occurring in the subcutaneous tissue and other locations, but is rarely found in the gastrointestinal tract. Histologically, it is comprised of adipose tissue and proliferative blood vessels and is usually diagnosed postoperatively. This report focuses on the importance of correct pre- and/or intraoperative histological diagnosis in order to offer the best therapeutic choice with the diagnosis confirmed postoperatively.

Angiolipoma was first described in 1912 by Bowen[1]. In 1960, Howard[2] demonstrated that the clinicopathological features of angiolipomas differed from those of lipomas, thereby delineating angiolipoma as a new entity. It can be classified by the ratio of adipose and vascular tissue composition as predominantly lipomatous or angiomatous type[3]. Cytogenetic analysis shows the normal karyotype of angiolipomas contrasts with the various other types of benign lipomatous tumors, most of which show rather specific clonal chromosomal aberrations[4], which suggests that the pathogenesis of angiolipomas may be different from that of ordinary lipomas. Angiolipomas usually develop as encapsulated subcutaneous tumors, most commonly on the arms and trunk in young adults. They are rarely larger than 2 cm in diameter, frequently multiple in number and characteristically tender or painful[5]. They are rarely found in the gastrointestinal tract. In a literature review, we found only 22 cases of angiolipomas involving the gastrointestinal tract. Of these, one was located in the esophagus[6], three in the stomach[7–9], two in the duodenum[10, 11], six in the small intestine[12–17], three at the ileocecal junction[18–20], five in the colon[3, 10, 21–23], and two in the rectum[24, 25]. Angiolipomas in the gastrointestinal tract usually do not have specific clinical manifestations. Patients are often asymptomatic when the tumor is small. With increasing size of the tumor, they may experience abdominal pain, abdominal distension, melena, and symptoms of intussusception and bowel obstruction. Colon angiolipoma with intussusception, as seen in this case, is rare and may require urgent surgical intervention. Only two such cases have been reported in the literature[23, 26].

Radiological examination including barium radiographs, enteroclysis, abdominal ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) can detect the lesion in the gastrointestinal tract before histopathological diagnosis. Barium enema[3] and enteroclysis[17] may show a filling-defect in the lumen which usually appears as a hyperechoic lesion on transabdominal ultrasonography[3, 16] and a submucosal lesion in the gastrointestinal wall in endosonography[6] with central high signal intensity and peripheral iso-signal intensity on T1-weighted inphase images[17]. CT image characteristics depend on the tissue composition of the lesion, from a lipomatous type comprised of fat without contrast enhancement, which is often diagnosed as a lipoma[27], to a low-fat containing tumor showing numerous small round density enhancements[28, 29]. In 1998, Mintz and Mengoni[30] reported the use of sonography to diagnose a breast angiolipoma, which appeared as a homogeneously hyperechoic density on echogram. Chen et al.[3] also reported the successful use of imaging to diagnose an angiolipoma that was later confirmed with surgical pathology. However, the overall pre-operative diagnostic accuracy for gastrointestinal angiolipomas is quite low due to the non-specific clinical presentations and lack of specific findings on imaging studies. Error in diagnosis can lead to inappropriate surgery such as an unnecessary radical resection because of an erroneous preoperative diagnosis of colon cancer. The correct diagnosis of gastrointestinal angiolipomas is usually made intraoperatively and confirmed by final surgical pathology. When possible, an intraoperative biopsy with frozen section may provide an accurate diagnosis to guide surgery. In our case, preoperative biopsy during colonoscopy only showed non-specific inflammation without tumor cells. Combined with the CT findings, we doubted the presence of colon cancer and elected to obtain intraoperative frozen sections, which indeed revealed a benign process, thus avoiding an unnecessary radical resection.

The treatment options for colon angiolipoma vary depending on the type of lesions. Small pedunculated polyps can be removed under colonoscopy. Injection of epinephrine,and the use of nylon loop or metal hemostatic clips prior to polypectomy may effectively decrease intraoperative bleeding[10, 22]. For large lesions or broad-based polyps, surgical excision is the treatment of choice. Compared to endoscopic excision, surgical resection may reduce the risk of perforation and hemorrhage in these patients[3]. However, minimally invasive procedures such as laparoscopic resection may be possible. Vandamme et al.[21] reported a case of cecal angiolipoma that was successfully treated with laparoscopy-assisted ileocecostomy and a five-year follow-up showed no recurrence. Ishizuka et al.[25] successfully treated a rectal angiolipoma through a transanal approach. Open surgical resection was chosen for our patient due to the large size of the tumor (8 × 6 × 6 cm) and evidence of colon intussusception which required urgent examination. Because angiolipomas are benign tumors, only limited colon resection should be performed provided that the tumor can be completely removed[19, 22]. Studies have shown[12, 25] that excellent prognosis can be expected with complete tumor removal although recurrence is high when the tumor is inadequately resected.

Angiolipoma is a benign tumor, commonly occurring in the subcutaneous tissue and is rarely found in the gastrointestinal tract. Error in diagnosis can lead to inappropriate surgery such as an unnecessary radical resection because of an erroneous preoperative diagnosis of colon cancer. We should focuses on the importance of correct pre- and/or intraoperative histological diagnosis in order to offer the best therapeutic choice.

Written informed consent was obtained from the patient for publication of this case report and any accompanying images.