pleomorphic liposarcoma

Primary
pleomorphic liposarcoma of the liver: a case report and literature review. Dynamic contrast-enhanced MRI of the abdomen. A A 16-mm mass lesion with both cystic and solid, lipid-containing components (arrow, T2WI). B Arterial phase (T1W1). C Portal phase (T1W1). The solid components demonstrated arterial enhancement followed by rapid washout in the portal phase (arrow, T1WI). D In-phase (T1W1). E Opposed-phase (T1W1). A signal drop can be observed on the opposed-phase image compared to the in-phase image (arrow)
surgicalcasereports.springeropen.com • CC-by-4.0
Pleomorphic
liposarcoma of bone: a rare primary malignant bone tumour. a AP and lateral b plain radiographs demonstrate an ill-defined radiolucent lesion in the proximal tibial metadiaphysis (black arrows) with posteromedial cortical destruction and adjacent ossification (black arrowheads). A medial soft tissue mass with low density raises the possibility of a fatty matrix (white arrow). A pathological fracture is present (white arrowhead)
clinicalsarcomaresearch.biomedcentral.com • CC-by-4.0
Pleomorphic
liposarcoma of bone: a rare primary malignant bone tumour. Magnetic Resonance Imaging (MRI) of the proximal tibial lesion. a Coronal STIR, b coronal T1-, c axial T1-, d axial T2-weighted and, e axial proton density with fat saturation. The images demonstrate an ill-defined proximal tibial medullary based lesion extending to the subarticular surface. There is extensive cortical destruction with an almost circumferential soft tissue mass, which has a spiculated appearance (black arrows) displacing the posterior muscles and popliteal neurovascular bundle. Tumour breaches the deep fascia anteriorly to extend into the subcutaneous tissues and penetrates the interosseous membrane to extend around the anterolateral tibial cortex. Heterogeneous partly high T1 signal suppresses with fat saturation sequences supporting a partly fatty matrix (white arrowheads). The pathological fracture is clearly seen extending transversely across the proximal tibia (white arrows)
clinicalsarcomaresearch.biomedcentral.com • CC-by-4.0
Pleomorphic
liposarcoma of bone: a rare primary malignant bone tumour. Axial CT and PET/CT imaging of the proximal tibial lesion. a Axial CT imaging shows medial cortical destruction and a large soft tissue mass containing areas of fat attenuation (white arrowheads) and ossification (black arrows). b A coronal fused PET/CT image shows there is marked FDG uptake in the proximal tibial tumour as well as in a lateral distal femoral metastasis (white arrow). No other lipomatous lesion or tumour is present
clinicalsarcomaresearch.biomedcentral.com • CC-by-4.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Pleomorphic liposarcomas are high-grade malignant neoplasms arising from adipocytic tissues characterized by a variable number of pleomorphic lipoblasts and the absence of areas of well-differentiated liposarcoma and other lines of differentiation.

Epidemiology

Pleomorphic sarcomas are rare and make up for less than 5% of all liposarcomas and for about 20% of pleomorphic sarcomas. Most commonly they occur in the 7 decade of life with men slightly more frequently affected. In children, they are extremely rare .

Clinical presentation

The most frequent symptom is that of a fast-growing painless tumor, pain and/or symptoms related to organ displacement are less common complaints .

Pathology

Pleomorphic liposarcomas are highly malignant neoplasms characterized by pleomorphic lipoblasts with features of pleomorphic spindle cell sarcoma or myxofibrosarcoma and in the case of the epithelioid subtype with sheets of carcinoma-like epithelioid cells . They commonly have necrotic and myxoid changes .

Location

The most frequent sites of involvement by pleomorphic liposarcomas are the extremities in about ⅔ of the cases. The lower limbs are more commonly affected. Less frequent locations include the following :

Rare sites of involvement are :

Subtypes

There is a single subtype, the epithelioid liposarcoma.

Macroscopic appearance

Macroscopically pleomorphic liposarcomas are usually large when detected, not encapsulated, sometimes well-demarcated or multinodular other times ill-defined and infiltrative and of yellowish-white color. They often feature areas of necrosis or myxoid change .

Microscopic appearance

The microscopic appearance of pleomorphic liposarcomas includes the following features :

  • infiltrative margins
  • varying proportions of pleomorphic lipoblasts
  • non-lipogenic background of undifferentiated pleomorphic sarcoma with spindle cells and multinucleated giant cells
  • possibly myxofibroma-like areas (≈50%)
  • areas of necrosis (≈50%)
  • epithelioid morphology (≈25%)
Immunohistochemistry

Different than well-differentiated or dedifferentiated liposarcoma immunohistochemistry stains are usually negative for MDM2 and/or CDK4. The epithelioid subtype might show positive stains for melan-A and/or keratins .

Genetics

Genetically most mutations involve TP53 and/or NF1. No amplification involving the MDM2 nuclear gene is seen .

Radiographic features

Pleomorphic liposarcomas look like nonspecific soft tissue masses with heterogeneous areas of necrosis and hemorrhage .Compared to other liposarcomas they contain less or no fatty-tissue. Like other tumors, they displace other organs or tissue.

Ultrasound

Usually appears as multilobulated with areas of low echogenicity .

CT

CT usually shows an unspecific heterogeneous soft- tissue density mass isodense to muscle with streaky enhancing areas .

MRI

On MRI pleomorphic liposarcomas will display a soft tissue mass with fibrous components that enhance .

  • T1: heterogeneous hypointense
  • T2: heterogeneous hyperintense similar to or slightly lower than fat
  • T1 C+ (Gd): heterogeneous enhancement

Radiology report

The radiological report should include a description of the following:

  • form, location and size
  • tumor margins
  • amount of solid and lipoid components
  • relation to other organs and/or structures

Treatment and prognosis

The management of pleomorphic liposarcomas includes resection and also shows a response to the combination of ifosfamide and doxorubicin, which makes (neo-) adjuvant chemotherapy another option .  Local recurrence happens in about 30-50%, distant metastases occur in up to 50% of the cases and the 5-year survival is in the range of 60% .

Increased tumor depth and more central location, as well as a greater size and higher mitotic activity, are associated with worse outcome .

Differential diagnosis

Conditions which can mimic the clinical or radiological presentation of pleomorphic sarcoma are any fast-growing soft tissue tumors and include :

See also

Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu pleomorphic liposarcoma:
Liposarkom
 
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