An old article from 2002 describes a method of steroid injections to shrink lipomas. It's courageous enough to state that nonexcisional treatments are now common. Well, it's been almost ten years and almost nothing has changed.

NONEXCISIONAL TECHNIQUES

Nonexcisional treatment of lipomas, which is now common, includes steroid injections and liposuction.

Steroid injections result in local fat atrophy, thus shrinking (or, rarely, eliminating) the lipoma. Injections are best performed on lipomas less than 1 inch in diameter. A one-to-one mixture of 1 percent lidocaine (Xylocaine) and triamcinolone acetonide (Kenalog), in a dosage of 10 mg per mL, is injected into the center of the lesion; this procedure may be repeated several times at monthly intervals.8 The volume of steroid depends on the size of the lipoma, with an average of 1 to 3 mL of total volume administered. The number of injections depends on the response, which is expected to occur within three to four weeks. Complications, which are rare, are the result of the medication or the procedure, and can be prevented by injecting the smallest total amount possible and by positioning the needle so that it is in the center of the lipoma. [http://www.aafp.org/afp/2002/0301/p901.html]

I consider this method as outdated and there are now better noninvasive methods available. And again, these kinds of methods treat just the symptoms, not the cause but it's still better than nothing.