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    -  Atram MA
    -  Deshmukh A
    -  Shivkumar V B
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Intraperitoneal dissemination of primary dedifferentiated liposarcoma of omentum simulating an ovarian cancer – A case report

 Department of Pathology, Mahatma Gandhi Institute of Medical Sciences, Sewagram, Wardha, Maharashtra, India

Date of Submission02-Oct-2020
Date of Decision04-Oct-2020
Date of Acceptance10-Feb-2021
Date of Web Publication12-Oct-2022

Correspondence Address:
VB Shivkumar,
Department of Pathology, Mahatma Gandhi Institute of Medical Sciences, Sewagram, Wardha, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijc.IJC_1128_20


Dedifferentiated Liposarcoma (DDLPS) is a rare subtype of liposarcoma with a high preponderance of local recurrence and distant metastasis. The frequent site of DDLPS is the retroperitoneum, followed by the limbs and trunk. The primary omental DDLPS is very rare and only a few cases have been reported in the literature. Here we report a rare case of primary giant DDLPS of omentum with intraperitoneal metastasis in a 61year old woman. The present case report adds to our knowledge, that a case of intraperitoneal DDLPS can mimic ovarian cancer clinically and should be considered in the differential diagnosis of a pelvic mass in postmenopausal women.

Keywords: Intraperitoneal, dedifferentiated, liposarcoma, omentum
Key Message Intraperitoneal Dedifferentiated liposarcoma can mimic ovarian cancer clinically and should be considered in the differential diagnosis of a pelvic mass in postmenopausal women.

How to cite this URL:
Atram MA, Deshmukh A, Shivkumar V B, Gangane NM. Intraperitoneal dissemination of primary dedifferentiated liposarcoma of omentum simulating an ovarian cancer – A case report. Indian J Cancer [Epub ahead of print] [cited 2022 Dec 2]. Available from:

  Introduction Top

Soft-tissue sarcomas (STS) account for less than 1% of all malignant tumors. Liposarcomas (LPS) are the most common intrabdominal STS, and the retroperitoneum is the commonest location.[1] Dedifferentiated Liposarcoma (DDLPS) is a rare subtype of LPS that displays high-grade morphology and metastasizes in 15–20% of cases.[2] Dedifferentiated Liposarcoma arising primarily in the intraperitoneal sites such as the omentum is extremely rare and less than ten cases have been reported till date.[2],[3]

We herein report a rare case of DDLPS of omentum with intraperitoneal dissemination along with a review of reported cases in the literature.

  Case Report Top

A 61-year-old woman presented with lower abdominal pain and lump of 15 days duration. She had no significant past gynecological and surgical history and her bowel and bladder habits were normal.

On physical examination, she was thin built and had a large abdominal lump extending from hypogastrium up to the umbilicus involving both flanks. The mass was soft to firm in consistency, nontender and did not move with respiration. Contrast-enhanced computer tomography (CECT) abdomen and pelvis revealed intraperitoneal well-demarcated, multilobulated abdominal-pelvic heterogeneously enhancing solid mass measuring 25.5 cm × 23.7 cm × 21 cm, extending from L2 to S2 vertebral body levels [Figure 1]a and [Figure 1]b. Multiple peritoneal nodular deposits were noted in the right iliac fossa, largest measuring 5.1 cm × 4.2 cm × 4.1 cm. There was presence of free fluid in the peritoneal cavity.
Figure 1: (a and b) CECT abdomen, pelvis showing an intraperitoneal well demarcated multilobulated heterogeneously enhancing solid mass. (c) Post-operative specimen showing a large multilobulated circumscribed mass with peritoneal nodules. (d) Cut surface shows variegated appearance with myxoid areas, necrosis and hemorrhage

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The hematological and biochemical parameters were within normal limits. The tumor markers including carcinoembryonic antigen (1.9 ng/mL), CA19-9 (31 U/mL), alpha-fetoprotein (8 IU/mL) levels were within normal limits. However, Beta human chorionic gonadotropin (15.5 mIU/mL) and CA-125 levels (142.4 U/mL) were elevated. Ascitic fluid cytology was done which showed cellular smears with a bizarre round to spindle cells with high nuclear-cytoplasmic ratio, hyperchromatic nuclei with prominent nucleoli. Cytological features were suggestive of metastasis of high-grade malignancy probably carcinosarcoma of the ovary.

She underwent exploratory laparotomy, with the impression of ovarian cancer. A large multilobulated mass was identified arising from the greater omentum along with multiple nodules adjacent to the tumor. A total abdominal hysterectomy, bilateral salpingo-oophorectomy, with debulking surgery of omental mass, and multiple metastatic deposits on the peritoneum, was performed.

On gross examination, omental mass measured 25.5 cm × 23.5 cm × 21 cm and weighed 3750 GM [Figure 1]a and [Figure 1]b. The cut surface showed variegated appearance with myxoid areas, necrosis and hemorrhage [Figure 1]c and [Figure 1]d. Histopathological examination revealed partially encapsulated tumor composed of spindle cells, arranged in short and long fascicles and in herringbone pattern [Figure 2]a. At places prominent irregular thin-walled vessels simulating hemangiopericytomatous pattern was also noted [Figure 2]b. The tumor shows a zone of transition between the well-differentiated area of the oval to spindle-shaped cells with univacuolated and multivacuolated lipoblast [Figure 2]d intermingled among tumor to a high-grade sarcomatous area with extensive areas of necrosis, hyalinization and myxoid changes [Figure 2]c Abnormal mitotic figures (6–8/10 HPF), tumor giant cells and inflammatory cells were also noted. Sections from the uterus, both ovaries and tubes were unremarkable except for left parametrium. Sections from separately sent peritoneal biopsies showed tumor deposits.
Figure 2: Photomicrograph of high grade DDLPS (a) Herring-bone pattern of reminiscent of fibrosarcoma, (H and E, 40×) (b) Prominent irregular thin wall vessels simulating hemangiopericytoma (H and E, 40×) (c and d) Multivacuolated lipoblast (arrow) are noted in myxoid stroma. (c) H and E, 40× d- 100×) (e and f) Immunohistochemistry – Tumor cells are positive for SMA and S-100 (40×)

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On Immunohistochemistry, desmin and C-kit were negative while Murine double minute 2 (MDM2), Smooth muscle actin (SMA) [Figure 2]e and S100 [Figure 2]f were positive in well-differentiated areas. A diagnosis of DDLPS was given on the basis of histopathological and immunohistochemical findings. The patient recovered well postoperatively, she was further referred to the medical oncology department and started on doxorubicin and ifosfamide chemotherapy.

  Discussion Top

Liposarcomas constitute one of the most common soft-tissue tumors (15% of all STS cases).[1] According to the 2020 WHO Classification of Tumors of Soft Tissue and Bone, LPSs morphologically classified into well-differentiated LPS, dedifferentiated LPS, myxoid LPS and pleomorphic LPS.[4] DDLPS account for almost 10% of all the liposarcomas, usually presents in middle-aged and older individuals with retroperitoneum as the most common site followed by extremities and thigh.[1],[3] DDLPS arising from omentum is extremely rare and nine cases have been reported in the literature after an extensive search [Table 1].[2],[3],[5],[6],[7],[8],[9],[10],[11]
Table 1: The characteristics of the reported cases of dedifferentiated liposarcoma of omentum

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DDLPS represents a progression from low-grade, well-differentiated LPS to high-grade, nonlipogenic sarcoma with an abrupt transition between the two components.[5] Therefore, on the basis of cellular pleomorphism, mitotic activity and necrosis, DDLPS divided into low and high grade.[3]

The patients with DDLPS remain asymptomatic or have nonspecific symptoms of abdominal discomfort until they reach to the large size to cause pressure symptom. Radiological assessment is done preoperatively to ascertain the tumor location.[2] A needle core biopsy can be erroneous due to inadequate sampling, making it difficult to distinguish from other high-grade sarcomas. Therefore, post-operative thorough sampling of the tumor is mandatory as histopathology is the gold standard method of diagnosis of DDLPS.[5]

In the present case, the tumor showed myxoid stroma, predominant epithelioid pattern with heterologous hemangiopericytomatous, leiomyosarcomatous and homologous pleomorphic liposarcomatous components. The cellular well-differentiated liposarcomatous components with Univacuolated and multivacuolated lipoblast were also identified. MDM2 is the most frequent amplification in DDLPS (nearly 100%) followed by CDK4 amplification seen in 90% of cases. Therefore, a combination of immunohistochemical markers p16, MDM2 and CDK4 may help to diagnose DDLPS.

In the case report of DDLPS of mesentery, Meher S, et al.[5] found heterologous component resembling malignant fibrous histiocytoma. However, low-grade DDLPS with a tumor resembling myofibroblastic cells admixed with amianthoid fibers which are reminiscent of myofibroblastoma were reported by Cai M. et al.[2]

DDLPS has a strong propensity for local recurrences as well as distant lung metastases (10%–15%).[4] Tumor size (>20 cm), histological subtypes, and tumor dissemination are considered as important prognostic factors.[3],[1] Although the complete resection of greater omental mass is recommended, it was impossible for our case due to closed relation to vital structures and disseminated intraperitonal sarcomatosis. However, attempts have been to made to treat peritoneal sarcomatosis with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. Radiotherapy is also controversial in omental LPS due to its rarity and risk of radiation enteritis.[2]

The prognosis of an intrabdominal high-grade DDLPS is worse with the median 5-year disease-free survival rates of 20-40%.[1] Approximately 40% of DDLPS will have a local recurrence, 17% will metastasize, and of which lung, bone and liver are the most common site.[7] The grade and margins of resection are the predictors of local recurrence and distant metastasis; however, it is difficult for the intraperitoneal tumors.

Among the differential diagnosis of intraperitoneal soft-tissue lesions, gastrointestinal stromal tumor and leiomyosarcoma are common; however; metastasis of high-grade epithelial malignancy of the gastrointestinal tract has to be also ruled out.[1] In females as in the present case gynecological sarcomas particularly leiomyosarcomas, endometrial stromal sarcomas, carcinosarcomas should also be considered in the differential diagnosis of intraabdominal DDLPS.[1]

  Conclusion Top

Dedifferentiated liposarcomas of omentum are extremely rare. High-grade DDLPS has a poor prognosis and higher risk of local recurrence and distant metastasis. DDLPS of omentum sometimes simulates an ovarian malignancy, based on their anatomic location, radiological findings and serum tumor marker level, particularly in a postmenopausal woman.

Thus, the present case cautions about the difficulty in diagnosing giant intraperitoneal mass abutting ovaries with nonspecific elevation of tumor markers. Such cases of DDLPS should be considered in the differential diagnosis of a pelvic mass in postmenopausal women.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Levy AD, Manning MA, Miettinen MM. Soft-tissue sarcomas of the abdomen and pelvis: Radiologic-pathologic features, Part 2-Uncommon sarcomas. Radiographics 2017;37:797-812.  Back to cited text no. 1
Cai M, Siew CCH, Tay TKY, Tan GHC. Dedifferentiated liposarcoma with a rare presentation of disseminated intraperitoneal sarcomatosis: A case report. Int J Surg Case Rep 2019;60:331-5.  Back to cited text no. 2
Duman K, Girgin M, Artasc G. A case report: Giant intra-abdominal liposarcoma presenting acute renal failure. Ann Med Surg (Lond) 2016;12:90-3.  Back to cited text no. 3
WHO Classification of Tumors Editorial Board. Soft Tissue and Bone Tumors. Lyon (France): International Agency for Research on Cancer; 2020. (WHO classification of tumors series, 5th; vol. 3).  Back to cited text no. 4
Meher S, Mishra TS, Rath S, Sasmal PK, Mishra P, Patra S. Giant dedifferentiated liposarcoma of small bowel mesentery: A case report. World J Surg Onc World J Surg Oncol 2016;14:250.  Back to cited text no. 5
Hashimoto S, Arai J, Nishimuta M, Matsumoto H, Fukuoka H, Muraoka M, et al. Resection of liposarcoma of the greater omentum: A case report and literature review. Int J Surg Case Rep 2019;61:20-5.  Back to cited text no. 6
Alecu L, Costan I, Vitalariu A, Obrocea F, Gulinescu L. Liposarcom dediferenţiat al omentului [Dedifferentiated liposarcoma of the omentum]. Chirurgia (Bucur) 2001;96:399-404.  Back to cited text no. 7
Neves S, Belo-Soares P, Gil-Agostinho P, Teixeira L, Augusta Cipriano M, Caseiro-Alves F. Case 2182 Dedifferentiated omental liposarcoma. 2003 URL htps:// DOI: 10.1594/EURORAD/ CASE.2182. [Last accessed on 2021 Mar 09].  Back to cited text no. 8
Soufi M, Mdaghri J, Benamr S, Lahlou MK, Massrouri R, Essadel A, et al. Giant liposarcoma of the omentum mimicking an ovarian tumor. A case report. Indian J Surg 2012;74:425-7.  Back to cited text no. 9
Jung EE, Heinemann FS, Egelston CA, Wang J, Pollock RE, Lee PP, et al. Synchronous recurrence of concurrent colon adenocarcinoma and dedifferentiated liposarcoma. BMJ Case Rep 2019;12:e228868.  Back to cited text no. 10
Miwa T, Otsuji K, Aiba M, Kochi T, Toda K, Nakamura N, et al. Ultrasonographic findings and diagnosis of omental dedifferentiated liposarcoma: A case report. J Rural Med 2020;15:68-72.  Back to cited text no. 11


  [Figure 1], [Figure 2]

  [Table 1]


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