Official Journal of the American Society of Abdominal Surgeons, Inc.
This article originally appeared in the Winter 20011 / Spring 2012 issue of the Journal.
Retroperitoneal Lipoma Arising from the Left Mesocolon
Dr. Faris Dawood Alaswad, M.D., M.B.CH.B., F.I.C.M.S., F.I.C.S., F.A.C.S., F.E.B.S.
Dr. Sukrett Shetty, M.D., M.C.H.
Dr. Vickrant Malhotra, M.D., F.R.C.R.
NMC Speciality Hospital
Retroperitoneal benign lipomas are extremely rare and represent about 2.9% of all primary retroperitoneal tumors. About 80% of the tumors in the retroperitoneal cavities are malignant neoplasms. We experienced a case of a retroperitoneal lipoma. A diagnosis was correctly made by magnetic resonance imaging (MRI) prior to surgery, and a total tumorectomy was performed. Histological sections revealed a tumor consisting of typical adipose cells without atypia. These types of lipomas should be carefully followed-up because they often recur and undergo malignant transformations.
Keywords: lipoma, rectroperitoneum, magnetic resonance imaging
Primary retroperitoneal tumors represent about 0.2% of all neoplasms.1 Out of these about 80% of the tumors are malignant neoplasms.2, 3 Retroperitoneal benign lipomas are extremely rare, and represent about 2.9% of all primary retroperitoneal tumors. Herein we present a case of a large retroperitoneal lipoma prior to resection.
A 45 years old male complain from vague abdominal pain. He did not have a medical history of surgery or concomitant medications. Upon abdominal examination, an ill-defined and soft mass was detected in the (Lt) abdominal cavity. He had fullness in the (Lt) hypochonderium region. Abdominal ultrasound showed an echogenic mass without any solid portions in the (Lt) iliac region. These observations suggested a tumor containing fat. An MRI revealed a mass measuring 35cm in the left retro pelvic cavity, which showed high intensities on T1 and T2 weighted images that were the same intensity as fatty tissues. Another MRI showed that the tumor was in the retro pelvic cavity left iliac artery and vein involved and surrounded by the tumor. The patient underwent surgery with a diagnosis of a retroperitoneal lipoma. Macroscopically an encapsulated, yellowish and soft mass lay between the left colon and the left iliac vessels in the left retro pelvic space. The tumor penetrated the left meso colon, and had feeding vessels from that. The tumor showed strong adherence to the urinary bladder and left colon but did not infiltrate the surrounding organs. The tumor was thought to be a large lipoma arising from the left meso colon therefore, a total tumorectomy was performed.
Histological section revealed a tumor consisting of typical adipose cells without atypia. Neither lipoblasts nor malignant cells were observed in the sections, and the histo-pathological diagnosis was that of a lipoma. The patient had no post operative complications, experienced less abdominal discomfort and was discharged on post operative follow up period. Most lipomas are superficial, and retroperitoneal lipomas are very rare. When lipomas occur in retroperitoneal locations, they are mostly renal in origin.4, 5 A few reported cases have a pancreatic origin,2,3,4 and so on. Pelvic lipomas are exceedingly rare, but can arise from the iliac vessels and Para vaginal tissues.1, 2 One reported case with pelvic origins demonstrated a urinary bladder outlet obstruction secondary to a pelvic lipoma. To our knowledge, the present case arising from the left mesocolon is the first such reported in the world. The lipoma presented herein was characterized by the diffuse overgrowth of fatty tissues in the retrocolic spaces, but lacked any colonic obstructions. The patient experienced only slight abdominal pain.
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MRI presents greater diagnostic precision than ultrasonographies and computerized tomographies (CTs). In the present case the ultrasound son graph showed an echogenic mass without any solid portion in the abdominal region. On MRI the lipomatous components showed very high signal intensities on the T1 weighted and T2 weighted images. Therefore, MRI are effective for diagnosing retroperitoneal lipomas.
Benign and malignant liposarcoma are well documented and are characterized by chromosome 12 aberrations.3, 4, 5 Recently, some retroperitoneal lipomas were shown to have no detectable rearrangements of chromosomes 12 or its amplification. On the other hand, retroperitoneal lipomas have shown rearrangements in chromosomes 1 and 8.5 Therefore, there are different chromosomal rearrangements between retroperitoneal lipomas and malignant liposarcomas. However, there are no significant optical differences in CTs or MRI is observed prior to surgery between lipomas well differentiated liposarcomas. Thus, one should consider the possibility of a liposarcoma when trying to resect a retroperitoneal lipoma. Furthermore, because these types of lipomas are known to recur and undergo malignant transformation, subjects with resected retroperitoneal lipomas must have careful follow-up.
1. Armstrong JR, Cohen I, Primary malignant retroperitoneal tumors. AM J Surg. 1965:110:937-43.
2. Pai MR, Naik R, Ragughuveer CV. Primary retroperitoneal tumors; 25 year study. Indian J Med Sci. 1995;49:139-41.
3. Cavazza A, Giunta A, Pedrazzoli C, et al. Extrarenal retroperitoneal angiomyolipoma; description of a case and review of the literature. Pathologica. 2001;91:44-9.
4. Hull WB, Blumenfeld ML, Jacques D. Large paravaginal pelvic lipoma: A case report. J Reprod Med. 1999;44:636-8.
5. Kimura N, Morita T, Murata A et al. A case of giant retroperitoneal lipoma. Nihon Rinsyo Gekagakkaishi. 2002;63:2030-4.
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