Introduction
Background
Lipomas are benign tumors composed of mature fat cells. They are the most common benign mesenchymal tumor. Lipomas are found in the subcutaneous tissues and, less commonly, in internal organs. They usually present with little difficulty in diagnosis or morbidity. Lipomas typically develop as discrete rubbery masses in the subcutaneous tissues of the trunk and proximal extremity. They usually are a few centimeters in size and can be removed by surgical excision or liposuction.
The eMedicine general surgery article Lipomas may be of interest, as may the Medscape Dermatologic Surgery Resource Center.
Pathophysiology
Lipomas differ biochemically from normal fat by demonstrating increased levels of lipoprotein lipase and by the presence of a larger number of precursor cells.
Approximately 60% of solitary cutaneous lipomas display clonal alterations. The most common alteration involves a breakpoint on bands 12q13-15. Karyotype aberrations also have been noted on arms 6p and 13q. Multiple lipomas do not display these alterations.
Frequency
International
In one study in a Scandinavian population, 43% of benign mesenchymal tumors were lipomas.
Mortality/Morbidity
No fatalities are reported with cutaneous lipomas. Mild tenderness occasionally is associated with the tumors. Angiolipomas often are tender.
Sex
Solitary lipomas are seen predominately in women. Multiple lipomas occur more frequently in men.
Age
Lipomas can occur at any age; however, they usually arise in early adulthood and are rare in children and infants.
Clinical
History
Patients usually give a history of a slowly growing lesion present for several years and usually do not complain of discomfort. Lipomas are classified in the following categories:
- Solitary lipomas (most common)
- Most solitary lipomas are superficial and small.
- Solitary lipomas may develop with weight gain but usually do not shrink after weight loss.
- Diffuse congenital lipomatosis
- Diffuse poorly demarcated lipomas localized primarily on the trunk characterize this type (see Media File 1).
- Tumors often infiltrate through muscle fibers, making them resistant to surgical removal. These tumors are composed of immature fat cells.
- Benign symmetric lipomatosis (Madelung disease)
- Madelung described the condition in 1888.
- Lipomas of the head, neck, shoulders, and proximal upper extremities characterize this condition.
- Men are affected 4 times as often as women.
- The patient's history often includes excessive alcohol consumption or diabetes.
- Other conditions associated with Madelung disease include malignant tumors of the upper airways, hyperuricemia, obesity, renal tubular acidosis, peripheral neuropathy, and liver disease.
- Familial multiple lipomatosis
- This clinical entity is characterized by few-to-many, small, well-demarcated, encapsulated lipomas that commonly involve the extremities.
- Typically, this form appears during or soon after adolescence.
- The neck and shoulders usually are spared (unlike benign symmetric lipomatosis).
- A family history of multiple lipomas usually exists, and an autosomal dominant mode of inheritance is found.
- Dercum disease (adiposis dolorosa)
- Painful lipomas are the hallmark of this rare condition.
- Lipomas typically occur on the extremities of obese postmenopausal women.
- Alcoholism, emotional instability, and depression commonly are associated with Dercum disease.
- Angiolipomas
- Typically, these tender, soft, subcutaneous nodules are present in adolescence.
- Tumors frequently are multilobulated and are somewhat firmer than ordinary lipomas.
- The associated pain is vague and may be spontaneous or caused by pressure.
- Hibernomas
- Tumors are solitary well-circumscribed nodules that typically are asymptomatic.
- Usually, tumors are located in the interscapular region, axillae, neck, or mediastinum.
- Histologically, hibernomas are composed of embryonic brown lipoblasts termed mulberry cells because of their appearance.
Physical
- Lipomas present as subcutaneous nodules of 2-10 cm.
- Lipomas often are lobulated.
- Consistency is rubbery.
- Skin overlying the lesion is normal and is not connected to the tumor.
- Neck, back, and proximal extremities are affected most commonly.
More on Lipomas |
 Overview: Lipomas |
| Differential Diagnoses & Workup: Lipomas |
| Treatment & Medication: Lipomas |
| Follow-up: Lipomas |
| Multimedia: Lipomas |
| References |
| Next Page » |
References
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Further Reading
Keywords
lipomatosis, Madelung disease, Dercum disease, adiposis dolorosa, angiolipomas, hibernomas, benign mesenchymal tumors, solitary lipomas, diffuse congenital lipomatosis, benign symmetric lipomatosis, familial multiple lipomatosis
