eMedicine Specialties > Dermatology > Malignant Neoplasms

Liposarcoma

Author: Robert A Schwartz, MD, MPH, Professor and Head, Dermatology, Professor of Pathology, Pediatrics, Medicine, and Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School
Coauthor(s): Matthew J Trovato, MD, Fellow, Division of Plastic Surgery, University of Medicine and Dentistry of New Jersey, New Jersey Medical School; Santiago A Centurion, MD, Staff Physician, Department of Dermatology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey
Contributor Information and Disclosures

Updated: Jul 16, 2009

Introduction

Background

Liposarcoma is a malignancy of fat cells (see Liposarcoma in the Pediatric Medicine section of eMedicine and Liposarcoma, Soft Tissue in the Radiology section of eMedicine). In adults, it is the most common soft tissue sarcoma. Liposarcoma normally appears as a slowly enlarging, painless, nonulcerated submucosal mass in a middle-aged person, but some lesions grow rapidly and become ulcerated early. Virchow first described liposarcoma in the 1860s.

The development of a liposarcoma from a preexisting benign lipoma is rare. Most cases arise de novo. Liposarcomas most frequently arise from the deep-seated stroma rather than the submucosal or subcutaneous fat. The most recent World Health Organization classification of soft tissue tumors recognizes 5 categories of liposarcomas: (1) well differentiated, which includes the adipocytic, sclerosing, and inflammatory subtypes; (2) dedifferentiated; (3) myxoid; (4) round cell; and (5) pleomorphic.

A spindle-cell variant of well-differentiated liposarcoma is also described. The concept that round-cell liposarcoma represents the high-grade counterpart of myxoid liposarcoma is generally accepted. Spindle-cell liposarcoma is a rare variant of an atypical lipomatous tumor (ie, well-differentiated liposarcoma), and it must be distinguished from a dedifferentiated liposarcoma with metastatic potential and a benign spindle-cell lipoma. The advent of cytogenetic and molecular investigations has contributed to better categorization of this subset of mesenchymal neoplasms. Not only have they provided new insights into the biology of these tumors, but they have also validated the current classification schemes based on conventional morphologic observations.1,2,3,4

Liposarcoma occurs in 3 main biologic forms: (1) well-differentiated liposarcoma; (2) myxoid and/or round cell; and (3) pleomorphic. In rare circumstances, lesions can have a combination of morphologic types; these are classified as combined or mixed-type liposarcomas.

The anatomical distribution of liposarcoma appears to be partly related to the histologic type. Well-differentiated liposarcoma tends to occur in deep soft tissues of both the limbs and the retroperitoneum. Myxoid and/or round-cell liposarcomas and pleomorphic liposarcomas have a striking predilection for the limbs, and dedifferentiated liposarcoma occurs predominantly in the retroperitoneum. Although any liposarcoma subtype occasionally arises in the subcutis, involvement of the dermis appears to be exceedingly rare.

Pathophysiology

Liposarcoma is a lipogenic tumor of large deep-seated connective tissue spaces. Fusion proteins created by chromosomal abnormalities are key components of mesenchymal cancer development. An abnormality of band 12q13 has been associated with the development of liposarcomas. The most common chromosomal translocation is the FUS-CHOP fusion gene, which encodes a transcription factor necessary for adipocyte differentiation.

Frequency

United States

Soft tissue sarcomas occur in approximately 5000 patients in the United States per year. Overall, liposarcomas account for less than 20% of all soft tissue sarcomas, and the average patient age at presentation is 50 years. However, in children, liposarcomas account for less than 5% of all soft tissue sarcomas; fewer than 60 cases in children have been reported.

International

With an annual incidence of 2.5 cases per million population, liposarcoma is the most common soft tissue sarcoma, accounting for approximately 17% of all soft tissue sarcomas and 3% of all liposarcomas in the head and neck region (usually the neck and the cheek). Oral involvement is rare; as of the year 2000, fewer than 50 oral cases had been reported. The trunk and the lower extremities are the most likely sites of tumor development.

Mortality/Morbidity

  • The overall 5-year survival rate of patients with deep high-grade liposarcoma is less than 50%.
  • Metastases are common, especially in poorly differentiated liposarcomas. The lungs and the liver are the most common sites of metastasis.
  • Primary cutaneous liposarcoma has an indolent course.

Race

No association with race or geography is known.

Sex

Liposarcomas are slightly more common in males than in females.

Age

The mean patient age at onset is 50 years. Although liposarcomas account for about 17% of all soft tissue sarcomas, they are involved in only 4% of childhood soft tissue sarcomas. Cases of liposarcoma are reported in young adults and teenagers, but cases in children are rare.5

Clinical

History

Liposarcomas are most commonly found in the extremities; in the retroperitoneum; and, less often, in the head and neck area. These tumors are most likely to arise from deep-seated, well-vascularized structures than from submucosal or subcutaneous fat.

Liposarcomas of all subtypes can occur in the cutis and the subcutis; however, their primary occurrence in the skin is rare. Clinically, all cases of liposarcomas in the skin tend to grow in an exophytic manner, presenting as either dome-shaped or polypoid lesions. In all patients, the neoplasm is centered in the dermis, and it has a minimal tendency to grow downward into the underlying subcutaneous adipose tissue.

  • Most patients with liposarcoma have no symptoms until the tumor is large and impinges on neighboring structures, causing tenderness, pain, or functional disturbances.
  • In the retroperitoneal area, where liposarcoma is detected at a late stage, the tumor may grow to a substantial size, weighing several pounds at the time of diagnosis.
  • In general, liposarcoma grows silently, and the patient's estimation of the clinical duration is often unreliable. The patient eventually becomes aware of a swelling or a mass and reports this finding to the physician.
  • Patients may report the following:
    • Associated episode of trauma to the region containing the mass
    • Painful swelling (occurs in one third of cases for as long as 6 mo)
    • Decreased function (ie, range of motion)
    • Numbness
    • Enlargement of varicose veins
    • Fatigue
    • Abdominal pain
    • Weight loss
    • Nausea
    • Vomiting

Physical

The 3 most common locations of involvement are the thighs, the retroperitoneum, and the inguinal region.

  • Liposarcoma usually appears as a well-circumscribed palpable mass as large as 10 cm in diameter.
  • The mass tends to grow slowly over time.
  • The lesion is commonly not tender on palpation.
  • Diffuse abdominal enlargement may be observed in patients with retroperitoneal disease.
  • Fascial compartmentalization may cause liposarcomas to have awkward discoid and fusiform shapes rather than smooth, round forms. Thus, liposarcoma can appear with an array of clinical morphologies and manifestations.
  • Other aspects to note on physical examination are neurologic involvement and lymphadenopathy.

Causes

No well-established causative factor has been identified, although trauma has been implicated.

More on Liposarcoma

Overview: Liposarcoma
Differential Diagnoses & Workup: Liposarcoma
Treatment & Medication: Liposarcoma
Follow-up: Liposarcoma
References
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References

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Further Reading

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Keywords

liposarcoma, atypical lipoma, atypical lipomatous tumors, malignancy of fat cells, soft-tissue sarcoma, soft tissue sarcoma, well-differentiated liposarcoma, dedifferentiated liposarcoma, myxoid liposarcoma, round cell liposarcoma, round-cell liposarcoma, pleomorphic liposarcoma, inflammatory liposarcoma, cutaneous liposarcoma, dermal liposarcoma

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Contributor Information and Disclosures

Author

Robert A Schwartz, MD, MPH, Professor and Head, Dermatology, Professor of Pathology, Pediatrics, Medicine, and Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School
Robert A Schwartz, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Physicians, and Sigma Xi
Disclosure: Nothing to disclose.

Coauthor(s)

Matthew J Trovato, MD, Fellow, Division of Plastic Surgery, University of Medicine and Dentistry of New Jersey, New Jersey Medical School
Disclosure: Nothing to disclose.

Santiago A Centurion, MD, Staff Physician, Department of Dermatology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey
Santiago A Centurion, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, and Sigma Xi
Disclosure: Nothing to disclose.

Medical Editor

Jacek C Szepietowski, MD, PhD, Professor, Vice-Head, Department of Dermatology, Venereology and Allergology, Wroclaw Medical University; Director of the Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Poland
Disclosure: Stiefel Salary Employment; Orfagen Consulting fee Consulting; Maruho Consulting fee Consulting; Astellas Consulting fee Consulting

Pharmacy Editor

David F Butler, MD, Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic, Northside Clinic
David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa
Disclosure: Nothing to disclose.

Managing Editor

Jeffrey P Callen, MD, Professor of Medicine, Chief, Division of Dermatology, University of Louisville School of Medicine
Jeffrey P Callen, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Physicians, and American College of Rheumatology
Disclosure: Amgen Honoraria Consulting; Abbott Honoraria Consulting; Electrical Optical Sciences Honoraria Consulting; Centocor Honoraria Consulting; Medicis Honoraria Consulting; Celgene Honoraria Consulting

CME Editor

Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University
Catherine Quirk, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology
Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology
Disclosure: Nothing to disclose.

 
 
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