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Duke Orthopaedics
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Wheeless' Textbook of Orthopaedics

Lipoma


- See: Soft Tissue Menu

- Discussion:
    - benign tumor composed of lobules of mature fat;
    - most common tumor of soft tissue;
    - occurs most often in adults;
    - tumor usually presents as active stage 2 lesion, later becoming latent;
    - usually it appears as soft, slowly enlarging, asymptomatic mass located superficially in subQ tissues, commonly seen in the back, buttocks, and thighs;
    - it can also appear deep to the fascia, lying in fatty planes along N/V bundles;
           - lipomas do not cross fascial boundries but will grow in between fascial planes;
           - lipomas that arise in deep tissues may become remarkably large;
           - these lesions may have a firm consistency similar to a sarcoma; 
    - diff dx: liposarcoma: most occur proximal to the knee and elbow; 
    - sub-types:
           - intra-muscular lipoma:
                  - these lesions can become large in size before detection;
                  - typically has a firm consistency which mimics sarcoma;
                  - often these lesions will be in close contact w/ neurovascular bundle;
           - angiolipoma:
                  - variant of lipoma w/ vascular component, occurs in children as a deep, subcutaneous or intramuscular soft mass;
                  - it is distinguished from ordinary lipoma by distinct tenderness to palpation;
                  - angiography is the best method for diagnosing angiolipoma;
                  - note that in the majority of cases multiple tumors may be present;
                  - diff dx:
                         - Kaposi's sarcoma;
                         - angiosarcoma
           - spindle cell sarcoma:
                  - presents as a painless nodule;
                  - histologically the tumor contains a mixture of fat and spindle cells


- Radiographic studies:
    - crisply marginated radiolucent image;
    - may show calcification in areas of necrosis and metaplastic bone or cartilage;

- MRI:
    - w/ lipoma, signal intensity of lesion parallels that of subcutaneous fat on all pulse sequences (T1 and T2);

         

- Bone Scan:
    - usual avascular lipoma appears avascular on bone scan;
    - if bone scan is hot consider liposarcoma;


- Treatment:
    - marginal excision is successful for lipoma, and recurrences are rare;
    - note that lipomas cannot be read by frozen section, and can only be interpreted by permanent sections



Intraosseous lipomas. A clinicopathologic study of 66 cases.

Size, site and clinical incidence of lipoma. Factors in the differential diagnosis of lipoma and sarcoma.

A 20-year retrospective review of surgically treated liposarcoma at the Cleveland Clinic.

Atypical Lipomatous Tumors/Well-differentiated Liposarcomas: Clinical Outcome of 67 Patients



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, December 27, 2011 11:42 am