• Jena Martin MD

Time looking at fences

Imagine if you will staring at a chain link fence.

That’s it, usually a white background, nothing else to cloud your view. The light is good, your neck is not too strained. Look closely. Are there differences in the shapes that the wire of the fence creates? Are the empty spaces the same? Are they different? Do they vary in any pattern you can see – flattened in one area, enlarged in another?

This, I promise you, is analogous to learning how observe a lipoma. Although the process starts at the grossing station the road to diagnosis ends under the microscope. After a lipoma is cut up into small nickel-sized chunks, it is processed in a series of harsh chemical rinses. These rinses remove the fat, leaving empty spaces. The tissue is then sliced and placed on a glass slide for the microscopic review. The pathologist will review the histology, also called the microscopic anatomy, and for fat, it’s pretty easy. Those chain link fence spaces again.

Why are we looking at this kind of unremarkable fatty tissue? A lipoma is a benign tumor of the fat. Rarely, a malignancy called a liposarcoma can mimic a lipoma. Usually a liposarcoma has odd and enlarged cells that grow within the wire-like areas dividing the fat cells (we call it the interstitium). Sometimes though, just variation in fat cell size is important and indicates something is wrong. It can mean local damage to the area or an inflammatory process. Either one of these cues - variation is size and enlarged cells - triggers the pathologist to consider ordering additional tests. *

In training I spent many hours reviewing these tumors; in common practice lipomas of the skin are zipped through, a simple diagnosis and confirmation of the doctor’s impression. When I confessed my earlier overzealous scrutiny to a superior, he told me:

“No time spent looking at slides is a waste”.

This is a good truism if you want to learn anything. The more time you put into preparing and learning material, the better. Time is the best way to add to your visual database and makes you more efficient in the future.

*Molecular tests for atypical lipomas or liposarcomas look for an increase in a particular protein called MDM2, the product of the gene MDM2. This protein can shut off the p53 tumor suppressor gene, which ultimately can cause unregulated cell growth. Tests (Fluorescence in situ hybridization tests FISH), are performed to look for increased MDM2 in tissues. This test can be helpful if the lipoma is very large, if it arises in a particular anatomic location, or if other cues such as radiology indicate it may harbor malignant changes.