Definition

Lipomas are quite common and arise from benign fat (adipose) tissue. Lipomas may also grow near or surrounding important peripheral nerves. Therefore, their removal can cause nerve injury and possible paralysis. Common locations include the neck, buttock, and forearm. Although lipomas are usually benign, large lipomas that are painful or are growing quickly may in fact be cancerous. Therefore, a doctor should evaluate all new masses. The following discussion refers to lipomas involving nerves.

Diagnosis

For asymptomatic, superficial lipomas, a physical examination by your physician can confirm the diagnosis. For deeper lipomas, or if there is any concern of malignancy, an MRI is ordered to fully evaluate the mass. Depending on lipoma size, location, and symptoms, a biopsy or removal may be recommended to confirm the diagnosis.

MRI example of a lipoma located deep in the neck.

Treatment Options

Small, asymptomatic lipomas, especially in older patients, may be observed on serial MRIs or physical examination. If a lipoma surrounds an important nerve, then irritation to this nerve or growth of the lipoma may mean it needs to be removed. In general, it is safer to remove smaller lipomas than larger ones. Sometimes, partial removal is indicated so as to protect the nearby nerve. If pathology reveals that a lipoma is malignant (e.g., atypical lipoma, or liposarcoma), then re-operation, radiation, chemotherapy, or just close observation may be recommended. In general, symptoms improved after surgery.

Surgery

Surgery varies depending on the lipoma location. Nearby nerves are preserved during surgery, both with close microscopic observation, as well as with intra-operative electrical monitoring of the nerve in question. It is always top priority to preserve the nerve, except in rare cases of malignant lipomas where a wide surgical margin is important. The surgery is usually performed under general anesthesia. Although most lipomas can be removed without much manipulation to nearby muscles, occasionally muscles need to be cut and re-attached to safely remove a deep lipoma (e.g., in the buttock). If muscles are not cut, then postoperative pain is quite minimal. Surgery often takes approximately 2-4 hours.

Intraoperative example of a large lipoma
being removed from the sciatic nerve.

Complications

Risks depend on lipoma size and location. If an important motor nerve runs through the lipoma, then removal may injure this nerve. Intraoperative nerve stimulation helps locate the nerve to ensure its preservation. Biopsies also have the risk of nerve injury.

Day of Surgery

Depending on lipoma location, surgery is performed either in day surgery or the main operating room. Do not eat or drink after midnight the day before surgery. You may take your usual medications with a sip of water the morning before surgery. You will wake up in the operating room and then be transferred to the recovery room where you can visit with your family. About one or two hours later, you either will discharged home with family or friends, or transferred to the neurosurgery ward.

Recovery

The operated limb or region may be used for light activity during the first two weeks after surgery. Gentle range-of-motion exercises are encouraged. An occlusive dressing allows you to shower immediately after surgery. After three days this dressing is removed. Underneath are small sterile stickers on the wound that are left in place until you see your surgeon about one week after surgery. You may shower with these stickers. Pathology results are usually ready three to five working days after the surgery. You may return to light work within the first week or two, depending on your specific condition and job description. Resolution of preoperative weakness and numbness may take weeks to months to occur, depending on how long you had it before surgery. Starting two weeks after surgery, physical therapy is prescribed as needed.