A soft lump that was thought to be a benign tumor, lipoma. Needle aspirate revealed a malignant tumor, a mast tumor. Appearance and feel are very misleading.
May is Cancer Awareness Month!
Lumps and bumps are common under the skin of older pets. These lumps are often ignored because they are not painful to the touch. While only about a third of these lumps are malignant, there is no way to feel or look at a lump to determine if it is malignant. A pet may have multiple lumps that appear similar, while in reality they are not. Some may be benign (non-spreading, slow-growing) while others may be malignant (fast-growing, aggressive, and spread) on the same patient. Every lump should be identified with a fine needle aspirate and cytology (collecting cells with a small needle and examining with a microscope). In the cases when fine needle aspirates fail to yield enough cells to clearly identify the tumor, a biopsy should be submitted to a pathologist.
Even benign growths should be removed for the comfort of your pet as they often create pressure and discomfort as they slowly grow. Many may not appear painful to the touch, but the pressure against underlying nerves or muscles create unidentified pain and irritability. Lipomas are considered a very benign tumor but often are allowed to grow to large sizes that are very uncomfortable for the pets. A lipoma weighing one pound is very uncomfortable! (Try to imagine a one-pound box of butter hanging off your side or leg.) As a crude rule of thumb, any lump over two inches in diameter should be removed. Lumps on legs or smaller pets should be removed at an even smaller size of less than an inch.
Often people say, “It does not seem to bother the pet.” Ask this question to yourself, “If this lump was on my body would it bother me or be an irritation to me?” If you are unsure of the answer, or answer yes, you should have the growth removed. This is when I truly wish our pets could talk and tell us how uncomfortable they are. We would be shocked. Therefore, if in doubt, have the tumor removed.
