An educational post: old age lumps and bumps (?)

So, I often talk about cases here, as well as my personal life. Yet since that MD inadvertently got under my skin by presuming that vets are ... well ... not real doctors, I've been thinking about adding educational posts to my repertoire. Today's topic will be old age lumps and bumps in cats and dogs...benign or malignant? Why should I care??

So, it is true - as dogs and cats age, they often develops lumps, warts, bumps, and soft masses - just like people. Many of these are benign growths that have no significance for the animal. Some examples of these include lipomas (benign fatty tumors that are soft and easily moveable under the skin), sebaceous adenomas (small to sometimes large, cystic masses that are particularly common in cocker spaniels), and papillomas (warts, for lack of a better word).

So, as your dog ages - should you worry about these masses? Should you bring them to the attention of your veterinarian? Moreover, should you take your veterinarians advice and have them aspirated and/or biopsied?

The short answer is YES.

The reason can be summed up fairly simply - some masses may look benign but in fact are the opposite. The following is a brief list of some lumps that should not be ignored:

1) Mast cell tumors. These are a cancerous tumor of dogs (found frequently in Boxers) that grow on the skin. They can look like just about anything - from small, red, benign-ish appearing lumps to great, big, swollen, ulcerated areas. It just depends on the mast cell. Mast cells are important in the body for mediating allergic reactions. They are full of nasty substances like heparin and histamine. Anyone with bad allergies knows what histamine can do and why antihistamines are good for allergies. When a mast cell tumor degranulates, a local allergic reaction can occur leading to redness, itching, swelling, and other general allergic signs. These tumors are often confined to the skin in dogs, but it is possible for them to metastasize to the visceral organs - especially the spleen and liver. Thus, when these are identified, it is best to have them surgically removed. Diagnosis is usually quite easy on aspiration of the mass. Surgical removal can be curative, but it is important to keep an eye out for more mast cells tumors, as some dogs have multiple tumors. A hallmark behavior of these tumors is a waxing and waning behavior - becoming large, then shrinking, then becoming large, as well as itching. Cats on the other hand, often have visceral mast cells - they start on the inside, in the spleen or liver, and then metastasize to the skin.

2) Hemangiopericytomas. These are lumps found most often on the lateral (outside) surface of the limbs, usually down toward the feet. They are tumors about which we know very little. We theorize that they come from the endothelium (lining of blood vessels), but really - we don't know for sure. They are often very soft, squishy masses that bleed easily when irritated. They don't typically metastasize, but they can be extremely locally aggressive. Radical surgical excision is the recommended treatment. This might include amputation in some cases, depending on how large/aggressive the tumor is. Getting clean margins (i.e. ALL the cancer cells with a clean rim of normal tissue) is tantamount to success.

3) Cutaneous lymphoma or hemangiosarcomas. These are skin cancers that can be isolated to the skin or that can also be found metastasized internally. Depending on which cancer you're dealing with, these can be life-threatening (if metastasis is present). I admit I know little about cutaneous hemangiosarcoma. Surgery is the treatment modality of choice - with possible chemotherapy follow up - depending on the margins and metastasis. The most common form we see is splenic (on the spleen) or atrial (found on the right atrium of the heart) and that has a horrible prognosis in dogs (6-9months). Lymphoma, on the other hand, can be very dependent on type, location, etc. It's not a very well understood entity either, but can definitely be life-threatening.

4) Liposarcomas. These are a spectrum of the benign fatty tumors. They are fatty tumors that become deeply infiltrating. They can interfere with blood vessels, nerves, and organs, if they are deep enough. While not necessarily deadly in a metastatic way, they can interfere with gait, blood flow, and the like.

There are others, but these are the big players.

Another dirty little secret of cancer? It likes to hide. Just because your dog or cat has had one fatty tumor aspirated and confirmed as a lipoma does not mean that all the other tumors that FEEL like a lipoma are in fact, lipomas! Sometimes, in the center of those lipomas...are nests of cancerous cells. Sometimes you cut open a seemingly benign lipoma and smack in the middle is a sarcoma!

So, the answer?

Monitor your dog and cat for lumps and bumps - if they appear, it is always best to see your veterinarian. They may recommend aspiration (taking a needle, sucking out cells, and looking at them on a slide) or biopsy (taking a large piece or taking off the whole mass and submitting for histopathology). The best method is biopsy and histopathology, but this is a more expensive diagnostic option - and if you have a lumpy dog, could cost in excess of $1000 (average histopath at my hospital is $180/site).

Always have the lumps and bumps checked. It is especially important to have them checked if they grow rapidly, seem deep or fixed to a layer deeper than just below the skin, bleed, ulcerate, or otherwise seem irritated. It's better to know so early treatment can be pursued!