Can Lipoma Turn into Cancer?

Lipomas can not turn into cancer, however liposarcomas and other rare fatty tumors could potentially be present.  Lipomas are best removed by direct excision rather than liposuction.  Best Anil Shah

A benign lipoma would not turn into a malignant liposarcoma, but without taking a biopsy or removing the lesion, it is impossible to know for certain whether a particular mass is a benign lipoma or a very rare liposarcoma. A diagnosis made without removing some tissue for pathologic analysis is simply an educated guess. In most cases, excision of the lipoma (or at the very least a biopsy) is recommended.
All the best,

Lipomas can mimic cancer and vice-versa. It is always advisable to remove lipomas before they enlarge.  A pathologic specimen is sent to evaluate the tumor with a microscope. Raffy Karamanoukian MD FACS

Lipomas do not become or turn into cancer but a cancerous fat tumor called liposarcoma does exist, and can be quite aggressive. A liposarcoma will generally be firmer, more irregular, more adherent and less mobile than a lipoma. Also, liposarcoma is more likely to be painful than a lipoma. It is not always easy to determine if a mass that seems to be a lipoma might actually represent a liposarcoma. That is one reason to excise most lipomas if the diagnosis is in question ands to always send the tissue for a biopsy.

A lipoma by definition is NOT a cancer.  A lipoma will no turn into a cancer.  The tricky part is knowing, in fact, that you are dealing with a lipoma and not another type of tumor.  Other tumors such as liposarcomas or sarcomas may appear quite similar to a lipoma.  A formal evaluation may be very important in understanding your risks as it relates to cancer.  

Benign tumors (masses) do not turn into cancers. However, occasionally, a mass which is presumed to be a benign tumor before biopsy or removal and pathologic examination, turns out to be a malignant tumor (cancer). We recommend removing all masses that are large, symptomatic or growing to confirm the masses are benign. A core needle biopsy can be performed if one doesn't want to remove the complete tumor. The majority of soft tissue masses are benign.

Lipomas are the most common benign tumor;  they are composed of adipose tissue. Sometimes these soft,  usually mobile  masses can grow in size and become an aesthetic or functional concern.

Malignant transformation of lipomas into liposarcomas  it's extremely rare ( and controversial).

Generally, I  recommend excision to allow for pathologic evaluation (which is the only  way to make a definitive diagnosis) and to  alleviate compressive symptoms it may be causing (as well as for cosmetic purposes).

Best wishes. 

Greetings,
A true lipoma is not cancerous and will not turn into a cancerous tumor. Determining if a tumor is a lipoma though requires making a tissue diagnosis -- ie removing the tumor and examining it under a microscope. There is a rather unusual tumor called a liposarcoma which is a cancer. It is impossible to tell the difference between a liposarcoma and a lipoma based solely on physical examination or any imaging study (CT scan or MRI). If there is any doubt, take some kind of biopsy.

By definition, a Lipoma is a benign growth which does NOT turn into a cancerous tumor. However, even though we tend to call EVERY fatty tumor a "Lipoma", in reality we are guessing and playing the 99.9% odds that the tumor IS a benign tumor (because only a small number are not). To know for sure the identity of ANY mass or lesion, it needs to be presented to a Pathologist to look at under the microscope. Only a pathologist can officially determine the identity of any mass.
The most prudent thing to do is to have the mass removed when it is still small, to minimize your scarring and know definitively what it is. Odds are it would be a (benign) Lipoma.
Dr. P. Aldea

This is somewhat of a controversial area but most soft tissue pathologists feel that a long-standing lipoma does have the capability to transform itself into a liposarcoma.
This was first described by Wolgemuth in 1910 and there have been a number of papers since that time describing this phenomenon. Dr. Steven Hadju, in Pathology of Soft Tissue Tumors, mentions ten cases of his that did this.
Those who are skeptical of this phenomenon, point out that there may have been sampling error in the original specimen ( the benign-looking portion of the liposarcoma was taken) or the pathologist simply misread the diagnosis. Also,some argue that a lipoma was actually a well differentiated liposarcoma all along and was just not aggressive.
However, there are a number of instances when a stable, long-standing lipoma (20 plus years) rapidly enlarged and on removal was determined to be a liposarcoma.
There is a type of lipomosarcoma termed a lipoma-like liposarcoma which can look clinically (when palpated or touched) and histologically like a benign lipoma. This underlines the reason many of us do not feel liposuction should be done on these tumors without a good sampling of their contents.
I would recommend removal on another ground. Sometimes, lipomas can become symptomatic as they encroach on nerves and muscles. Also, they can enlarge an become physiciall quite deforming.