Pleomorphic liposarcoma

Definition

A high grade pleomorphic sarcoma containing pleomorphic lipoblasts.

Epidemiology

Pleomorphic liposarcoma accounts for only about 5% of all liposarcomas and for about 20% of all pleomorphic sarcomas.

Clinical features

This tumour occurs in late adulthood (range 18 to 93, median 63 years). It is often a deep-seated tumour predominantly of the thigh or elsewhere in the limbs girdles. Patients usually present with a mass, but occasionally with dyspnea, fever, SVC obstruction or pleural effusion. Rare subcutaneous cases have been reported.

Macroscopic appearances

Tumours vary form well-demarcated to infiltrating. Most are white to brown-yellow. Occasional cases show myxoid change or necrosis.

Histopathology

Most cases show microscopically infiltrating margins. Diagnosis relies on the identification of lipoblasts: in one third of cases, the lipomatous component is scanty.

Lipoblasts are large with hyperchromatic scalloped nuclei, prominent nucleoli and multivacuolated cytoplasm. The vacuoles appear sharply punched out. There are frequently nuclear pseudoinclusions and multinucleation.

 

Lipomatous component

malignant adipocytes

pleomorphic multivacuolated lipoblasts

hibernoma-like

 

 

Non-lipomatous component

MFH-like, storiform to pleomorphic

MFH, myxoid

round cell liposarcoma-like, but lacking a plexiform capillary network

spindle cell liposarcoma-like

pleomorphic rhabdomyosarcoma-like

pleomorphic leiomyosarcoma-like

myxofibrosarcoma-like

osteosarcomatous

carcinoma/rhabdoid-like, resembling renal cell carcinoma/adrenocortical carcinoma

haemangiopericytoma-like vasculature

paraganglioma-like

 

There may be pools of mucin. A lymphoid infiltrate may be present. Eosinophilic hyaline globules may be present. Mitotic rate vary from 3 to 125 per 10 HPF.

Variants:

Immunohistochemistry

 

S-100

cytokeratin: AE1/3 & C11

EMA

SMA

Desmin

CD34

CD68

 

lipogenic component

20/421

1/421

0/421

1/421

0/421

0/421

0/421

non-lipogenic component

5/491

0/501

13/491

24/491

9/481

18/451

6/461

 

Pleomorphic MFH-like

1/271

0/271

6/261

13/261

5/251

11/241

2/241

Storiform MFH-like

0/21

0/21

1/21

1/21

1/21

2/21

0/21

Myxoid MFH-like

3/191

0/191

2/181

5/181

2/171

10/171

2/171

Epithelioid carcinoma-like

1/111, 6/112

0/111, 5/112

4/111, 0/122

4/111

2/111, 0/122

1/101, 0/122

4/111

Round cell liposarcoma-like

0/111

0/111

2/111

4/111

0/111

0/101

0/101

Spindle cell liposarcoma-like

0/11

0/11

0/11

0/11

0/11

1/11

0/11

 

Occasional cases show small foci of skeletal muscle differentiation.

Differential diagnosis

Prognosis

Pulmonary metastases are common.

Poor prognosis is associated with:

References

World Health Organization Classification of Tumours, Tumours of Soft Tissues and Bone, IARC Press 2002.

1Gebhard, S., Coindre, J.M., Michels, J.J., Terrier, P., Bertrand, G., Trassard, M., Taylor, S., Chateau, M.C., Marques, B., Picot, V. and Guillou, L. Pleomorphic liposarcoma: clinicopathologic, immunohistochemical, and follow-up analysis of 63 cases: a study from the French Federation of Cancer Centers Sarcoma Group. Am J Surg Pathol 2002;26:601-16.

2Miettinen, M. and F. M. Enzinger (1999). "Epithelioid variant of pleomorphic liposarcoma: a study of 12 cases of a distinctive variant of high-grade liposarcoma." Mod Pathol 12(7): 722-8.

This page last revised 29.6.2004.

©SMUHT/PW Bishop