Skin Lumps
What To Watch Out For

Many pets are presented to us each week for skin lumps, often with an anxious owner at the other end of the leash fearing the worst.  The majority of skin lumps are benign (will not spread or cause disease), but they should always be examined and monitored closely.  Here are a few general guidelines to help you decide whether or not to worry.

Lumps that arise on the trunk are more likely to be benign than lumps that arise on an extremity.   In other words, we are most concerned with lumps that arise on the legs, tail, breasts, face, or ears.

Benign lumps tend to be soft and slow growing.  Malignant (cancerous) lumps are often red, ulcerated, firm, and/or bumpy.  They arise quickly and grow rapidly. 

As a general rule we are more concerned about skin lumps in cats than in dogs.  There are several types of benign skin growths in dogs (fatty tumors, warts, cysts); not so for cats. 

Can we look at a lump and tell if it is benign or not? No, we can never be 100% certain just from looking and feeling alone.  If we suspect a lump is benign we recommend doing an aspirate to confirm it.  An aspirate is a simple procedure that involves placing a needle into the lump and drawing out some cells to be examined under the microscope.  Aspirates do not require sedation and are about as painful as getting any injection-in fact the needle is the same size as the ones used for vaccinations.  If the aspirate reveals suspicious cells, we recommend having the growth removed.  If the aspirate does not reveal any concerning cells then, we recommend that you continue to monitor the growth at home.

If we suspect that a lump may be cancerous, we skip the aspirate go straight to surgical removal and biopsy. Fortunately in animal medicine we can be less concerned with cosmetics (they don’t have to fit into a bikini); if we think a lump is malignant we take wide margins and remove it all whenever possible.  Pets are rarely left with a visible scar thanks to their long fur.