Lipomas are common benign tumors that arise from the fat tissue in the subcutaneous layer of the skin. The tumor is surrounded by a thin capsule of connective tissue. Lipomas are typically located just beneath the surface of the skin, although sometimes they can be deeper, near or between muscle fibers. They can occur in various regions of the body but are commonly found in the neck, back, chest, and thighs. Most individuals have a single lipoma, but approximately 20% may have multiple lipomas.
The most common presentation of a lipoma is a soft, rubbery, painless, and freely movable lump beneath the skin's surface. The diagnosis is usually based on its appearance, including location, size, firmness, and mobility. Further investigations are rarely necessary.
In about 80% of cases, lipomas have a diameter of less than five centimeters. Lipomas tend to be relatively stable in size, although they can slowly grow over several years. Rare cases have been reported where lipomas exceed 20 centimeters and weigh several kilograms.
Lipomas rarely cause any form of symptoms. However, if a lipoma is located in an area subjected to significant pressure (e.g., when sleeping) or is positioned over a nerve, it can cause pain and discomfort. Angiolipomas, a rarer variant of lipomas composed of blood vessels, can be painful regardless of their size or location.
In extremely rare cases, lipomas can develop into cancerous tumors called liposarcomas. This is especially true for lipomas larger than five centimeters. Such cases should be evaluated with imaging tests (MRI). Additionally, other presumed benign lipomas that grow rapidly or become hard/painful should also be assessed with imaging.
The exact cause of lipomas is unknown, although genetics may play a role. The significance of trauma and viral infections has also been discussed.
Lipomas do not require treatment, but they can be surgically removed if desired or indicated. Usually, a single incision is sufficient to "shell out" the lipoma (not attached to surrounding tissues). The procedure is performed under local anesthesia and leaves a linear scar.
For larger lipomas, an alternative treatment option is liposuction of the lipoma itself.
A sebaceous cyst (epidermoid cyst) is another benign condition that can resemble lipomas. In rare cases, skin lumps may indicate cancer or other serious illnesses. Therefore, it is important to consult a doctor for a clinical examination and evaluation. All skin and subcutaneous tumors should be taken seriously and monitored over time.
