|Year : 2012 | Volume
| Issue : 2 | Page : 314-316
Extremely rare giant retroperitoneal fibrolipoma: A case report
Bal Chander1, Mani Krishna1, Sita Thakur2, Neelam Mahajan2, Anju Vij2, Jeevan Diwakaran1
1 Department of Pathology, Dr. Rajender Prasad Government Medical College, Kangra at Tanda, Himachal Pradesh, India
2 Department of Obstetrics and Gynecology, Dr. Rajender Prasad Government Medical College, Kangra at Tanda, Himachal Pradesh, India
|Date of Web Publication||26-Jul-2012|
Department of Pathology, Dr. Rajender Prasad Government Medical College, Kangra at Tanda, Himachal Pradesh 176001
Lipomas are common benign adipose tumors generally located at superficial locations. Mostly they measure a few centimeters in size; however, giant lipomas measuring more than 10 cm in size or weighing 1000 g are also seen. Deep seated lipomas are rather infrequent out of which retroperitoneal location of giant lipoma is rare. Fibrolipoma is one of the uncommon variant of lipomas. A giant retroperitoneal fibrolipoma is extremely rare and only five case reports of such tumors are there in the literature. We herein present one such case in a 36-years-old female.
Keywords: Giant lipoma, giant retroperitoneal fibrolipoma, giant retroperitoneal lipoma, lipoma
|How to cite this article:|
Chander B, Krishna M, Thakur S, Mahajan N, Vij A, Diwakaran J. Extremely rare giant retroperitoneal fibrolipoma: A case report. J Can Res Ther 2012;8:314-6
|How to cite this URL:|
Chander B, Krishna M, Thakur S, Mahajan N, Vij A, Diwakaran J. Extremely rare giant retroperitoneal fibrolipoma: A case report. J Can Res Ther [serial online] 2012 [cited 2014 Jul 25];8:314-6. Available from: http://www.cancerjournal.net/text.asp?2012/8/2/314/99002
| > Introduction|| |
Lipomas, composed of mature adipocytes, are one of the most common benign mesenchymal neoplasms. Majority are encountered in a subdermal location in the upper half of the body, particularly the trunk and neck.  However, deep seated lipomas, particularly those originating in retroperitoneal space, are unusual if not rare.  Many case reports emphasize the large size of these benign tumors, which can be explained by the potential space available for tumor growth before they come to clinical attention. The symptoms result from pressure exerted by their excessive size on adjacent anatomical structures. Since liposarcomas are one of the most common sarcomas in the retroperitoneum, the most important differential diagnosis in such cases is well differentiated liposarcoma. Most lipomas are well defined and the presence of fat can be detected on pre operative CT scan or MRI.  Although, it is difficult to differentiate low grade liposarcoma from a benign lipoma based solely on CT scan or MRI findings, heterogeneity, areas of enhancement or necrosis, and irregular margins are often seen on the CT scan of a liposarcoma.  The final diagnosis rests on histopathological evaluation to assess mitotic activity, cellular atypia, necrosis and invasion.
Lipomas display a range of histopathological features and are subclassified into fibrolipoma, myxolipoma, chondroid lipoma, myolipoma, spindle cell lipoma, pleomorphic lipoma and angiolipoma. Fibrolipoma is one of the histological subtypes and is infrequently reported.  As the name implies, it has a prominent fibrous component in addition to mature adipose tissue element. There are case reports of fibrolipomas at various anatomical locations.  However, retroperitoneal or pelvic region giant fibrolipoma is extremely rare and to the best of author's knowledge there are only five case reports of such tumors in the literature. ,
| > Case Report|| |
A 36-year-old female presented with retention of urine for 13 days. Per abdominal examination revealed a mass arising from left side of the pelvis just above the symphysis pubis. Per vaginal examination revealed an ill-defined cystic mass through the left vaginal wall.
Routine laboratory investigations were normal. Ultrasonography of pelvis showed uterus displaced toward the right side by an echogenic mass measuring 81 × 74 mm in the left tubo-ovarian region with ill-defined margins. Computerized tomography scan revealed a mass measuring 136 × 112 × 91 mm in size, composed predominantly of fatty element with soft tissue strands arising from the retroperitoneal space, as well as from the floor and left lateral wall of pelvis pushing the rectum, urinary bladder and uterus toward the right side from the midline, suggestive of a liposarcoma. Bilateral ovaries were normal.
The patient underwent total abdominal hysterectomy and the mass was removed.
A fibrofatty encapsulated globular mass measuring 12.5 cm in diameter and weighing 1300 g was received. The cut surface was uniform yellowish except for a whitish fibrous area in the middle from which fibrous strands could be seen radiating toward the periphery. No areas of hemorrhage or necrosis were seen [Figure 1].
|Figure 1: Gross picture of well circumscribed tumor composed of yellow fat and white fi brous area in the center from which thin strands are radiating toward the periphery|
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The tumor consisted of mature adipocytes arranged in lobules, traversed by delicate vascular collagen septa in sections from the periphery [Figure 2] and thick bands of mature fibrous tissue in sections from the center of tumor [Figure 3]. The fibrous elements were composed of benign looking spindle shaped fibroblasts and the adipocytes were indistinguishable from normal adipose tissue [Figure 4]. No mitotic activity, cellular atypia, lipoblasts, necrosis or invasion was observed in the sections examined.
|Figure 2: Low power, H and E stained section from periphery of the tumor showing predominantly mature adipose tissue with a thin fi brous strand traversing through|
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|Figure 3: Low power, H and E stained section from center of the tumor showing lobules of mature adipose tissue and fi brous tissue almost in equal proportions|
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|Figure 4: High power, H and E stained section showing fibrous component of the tumor composed of spindle cells|
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| > Discussion|| |
Lipomas are adipose tissue tumors and constitute one of the most common benign neoplasms generally encountered in the fifth or sixth decade of life. The etiology is not clear and they are known to be both sporadic and inherited.  The cell of origin is believed to be the mesenchymal primordial fat tissue cells and not the adult fat cell. 
For reasons unexplained, lipomas are uncommon in the retroperitoneum where it constitutes approximately 2.9% of all primary tumors; nearly 80% of which are malignant. Most of these lesions have a predilection for adults. Most of the lipomas are well encapsulated but deep seated ones may be poorly circumscribed contributing to higher chances of recurrence or relapse. 
Fibrolipomas are one of the less common histological subtypes of lipoma. Majority of the published literature on fibrolipomas are in the form of isolated case reports. They are known to occur in diverse locations viz. esophagus, nerves, oral cavity and spermatic cord.  Retroperitoneal fibrolipomas are exceptionally rare, and to the best of our knowledge only five cases have been reported till date. 
Controversy exists whether retroperitoneal lipomas, especially giant lipomas (which by definition are at least 10 cm in diameter or weigh a minimum of 1000 g) are genuine lipomas or are well-differentiated liposarcomas. Celik et al has suggested that possibility of liposarcoma should be considered when a fatty subcutaneous tumor is more than 10 cm in diameter and has grown rapidly in recent months.  Histomorphological features of necrosis, invasion, mitosis or cellular atypia characterized by pleomorphism, hyperchromatic nuclei, prominent nucleoli and particularly the presence of lipoblasts can substantiate the diagnosis of a sarcoma. However, absence of lipoblasts due to inadequate sampling may result in an erroneous diagnosis of benign lipoma.
Though amplification of MDM2, and other markers like carboxypeptidase M(CPM), SAS, CDK4, DDIT3, or HMGA2 have been described to be confirmative, Macarenco et al failed to identify any of these parameters in their series of 19 cases of retroperitoneal lipomas, using fluorescence in situ hybridization. 
There is no evidence that the clinical profile, management and prognosis of fibrolipomas are different from other variants of lipomas. The treatment of choice is complete surgical excision, which in most cases is curative. Though these are histologically benign neoplasms, however recurrences or malignant transformations have been reported, for which a careful postoperative follow-up is necessary. 
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]