CASE 10789 Published on 15.03.2013

A large calcified dedifferentiated liposarcoma of the retroperitoneum

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

Briani C, Cappucci M, Bucciarelli A, Fantini C, Matteoli M, Di Pietropaolo M, Iannicelli E.

Radiology Unit,
Department of Surgical and Medical Sciences and Translational Medicine,
Faculty of Medicine and Psychology University of Rome,
Sapienza, Italy.
Sant’Andrea Hospital,
Via di Grottarossa 1035,
00189, Rome, Italy.
Email:elsa.iannicelli@uniroma1.it
Patient

70 years, male

Categories
Area of Interest Abdomen ; Imaging Technique CT
Clinical History
A 70-year-old man was admitted to our department with a 4-month history of intermittent abdominal discomfort. Physical examination revealed a palpable mass in the left side of the abdomen.
Imaging Findings
Abdominal computed tomography (CT) images show a large calcified mass (19x16 cm in size) in the left retroperitoneal space, containing both solid and fatty components, involving the perirenal adipose tissue and the left kidney (Fig.1).
The mass causes anterior displacement of the left kidney and descending colon, right displacement of the jejunum and inferior and superior mesenteric vessels, showing no evidence of infiltration of these structures (Fig. 2-3).
No enlargement of loco-regional lymph nodes was demonstrated.
Surgical excision was performed and the post-operative histopathological result was a calcified dedifferentiated liposarcoma (DDLPS) arising from well-differentiated liposarcoma (WDLPS).
The histological and immunohistochemical assay reveal the dedifferentiation status of the lesion characterised by areas of high grade sarcoma, fat necrosis, MDM2+, CDK4+, Vimentin +, and the well-differentiated one with CD34 +, S100 +, mature adipocytes proliferation.
Discussion
Liposarcoma is a soft tissue sarcoma which arises from fatty tissue, commonly found in the retroperitoneum, less in the lower extremities (3:1 ratio) [1].
Histologically it can be classified into three biologic forms: well-differentiated, myxoid and/or round cell, pleomorphic liposarcoma.

Dedifferentiated liposarcoma could be considered a subgroup of well-differentiated liposarcoma, first described by Evans in 1979 [2], characterised by a histologic dedifferentiation with a mixture of both well-differentiated liposarcoma components and transformed non lipogenic areas (normally at high-grade of differentiation)
About 10% of WDLPS undergo dedifferentiation as a time-dependent phenomenon.
Because of the slow growth of the tumour and the large potential space of the retroperitoneum, diagnosis is usually delayed due to the lack of symptoms.
The mass, in fact, could be an incidental finding in asymptomatic patients or become manifest in older age (5th - 6th decades of life) when the tumour grows enough to compromise adjacent vital organs.

Contrast enhanced CT and magnetic resonance imaging (MRI) play an important role in the diagnosis, staging and surgical planning of the disease.
Dedifferentiated liposarcoma has a predominant non-fatty solid component with a coexisting fatty one without a clear delineation between the two areas.
The fatty component reveals fat-attenuation on CT and high signal intensity (SI) on T1 and T2-weighted sequences with loss of SI on fat-suppressed sequences.
The non fatty areas show intense contrast enhancement and appear hypointense on T1 weighted sequences and hyperintense on T2 weighted sequences.
In addition CT shows a high sensibility for assessing calcifications that are present in more than 30% of cases and are associated with a worse prognosis [3].

The treatment of choice is the radical surgical resection obtaining a tumour free-margin, which is the most important predictor of local recurrence and survival.
DDLPS shows an incidence of local recurrence about 40%, occurring after a disease free interval of 10-20 years; distant metastases are reported in 15-20% of cases at 5 years follow-up [1].
Pre-operative radiotherapy could be useful to increase local control of disease but the use of radiation is limited by its high toxicity to the gastrointestinal tract, so the right role of preoperative radiation must be defined [4].
The use of chemotherapy remains under study [5, 6].
Differential Diagnosis List
Dedifferentiated liposarcoma (DDLPS) of the retroperitoneum.
Leiomyosarcoma
Rhabdomyosarcoma
Teratoma
Final Diagnosis
Dedifferentiated liposarcoma (DDLPS) of the retroperitoneum.
Case information
URL: https://www.eurorad.org/case/10789
DOI: 10.1594/EURORAD/CASE.10789
ISSN: 1563-4086