What is a lipoma?
Lipomas are the most common soft tissue tumours in adults. They are common in the upper limb and tend to occur more proximally around the shoulder region, but they can occur anywhere along the upper limb.
They are benign fatty tumours and are not cancerous. Fat cells within the lipoma become engorged and grow out of control. Lipomas aren’t related to obesity or diet. The most common age group for lipomas is 40-60 years.
Less than 1% of soft tissue lumps are malignant, and these can sometimes be mistaken for lipomas.
How can I tell if my lump is a lipoma?
Lipomas can be superficial/subcutaneous (under the skin) or deep. Superficial lipomas are often soft and rubbery well-defined lumps that are not painful and are mobile. Deep lipomas occurring within or between muscles can be more difficult to feel and may just appear as an asymmetric swelling compared to the other limb. Lipomas can range in size from less than 1cm to massive swellings.
Some lipomas may be atypical and still be benign while there are some fatty lumps that can be malignant, so it is important to tell the difference.
How are lipomas treated?
Lumps greater than 5cm should be investigated to ensure that they are benign lipomas and not something more sinister. For smaller lumps ultrasound can be good at diagnosing, but larger lumps, deep lumps, and atypical lumps may require MRI scans.
Small lipomas can often be left alone and just self-monitored by patients. Larger lipomas can sometimes press on local structures and cause symptoms or may be unsightly or catch on things and therefore may need surgical removal. A simple lipoma on the upper limb can be removed by an upper limb surgeon.
Atypical lumps, or any lumps that are suggestive of possible sarcoma or malignancy should be referred to a sarcoma service for further diagnosis and definitive treatment.
Can a lipoma become malignant?
A simple lipoma is a benign tumour that has no risk of becoming malignant.
Can a lipoma come back after it is removed?
There is a less than 5% chance of a simple lipoma recurring after removal.
When do I need to worry about a lump?
Any of the following signs should be a cause for concern and a lump with any of these features should be checked out promptly by a doctor:
Fixed to deep tissues
Changes to overlying skin
It is recommended that all lumps greater than 5cm (size of a golf ball) be checked to rule out a soft tissue sarcoma (a malignant condition).