Visiting Veterinarian : Jack and Jill
By Michelle Gerhard Jasny V.M.D.
Published: July 3, 2008
Jack is a statuesque golden doodle (a golden retriever/standard poodle cross). When he was four, his owners noticed a mass on his abdomen. I aspirated material from the lump with a needle and syringe and examined it under the microscope. "All I see is fat," I said. "It's probably just a lipoma - a benign, fatty tumor." Common in middle-aged to older dogs, lipomas typically feel like smooth, homogeneous lumps of subcutaneous fat. They are usually well circumscribed - you can feel distinctly where they begin and where they end - and freely movable, not fixed to the underlying body wall. They can occur anywhere but are most frequently found on the chest, abdomen, and upper legs. Lipomas can grow to be quite large but unless they are causing a functional impediment, there is no medical reason to remove them. My professor in vet school used to say, "Don't remove a lipoma until you have to take the dog off the tumor instead of the tumor off the dog." This statement was accompanied by a slide of a smallish beagle attached to a basketball-sized tumor protruding from her side, hanging down to the floor.
Jack's lipoma gradually grew larger, extending along his abdomen and groin. His family jokingly dubbed the lump "Jill" and wondered if it might be interfering with Jack's gait. The larger Jill got, the harder she would be to remove, so when a few new smaller lumps appeared in other places, his family decided we might as well remove them all. In our pre-surgical consult, I ran my hand over Jill. I couldn't feel definitive margins or move the mass freely. Sometimes lipomas grow beneath muscle layers which act like a girdle holding them firmly in place, but once you get in surgically and separate the muscle and connective tissue, these growths are still well-encapsulated and shell out easily. But not always. My mind drifted.
1981. My first surgical rotation in vet school. Shay - a magnificent golden retriever, about the same age as Jack. The owner, a quiet, thoughtful young man. Shay had been referred to the University of Pennsylvania specialists because he had a huge, poorly defined, fast-growing mass on his chest. Preliminary tests indicated the mass was a lipoma but that it might extend between the ribs and into the space around the lungs. "Occasionally a lipoma can act very aggressively," the surgeons explained to the owner as they prepared to take Shay to surgery. "Instead of being a discrete mass, an infiltrative lipoma spreads fingers of tumor, invading muscle and connective tissue, making them nearly impossible to remove completely." They also discussed the rare possibility of liposarcoma, a truly malignant tumor of the fat cells that is not only locally invasive but may metastasize to lungs, liver, spleen, and bone.
As the young man said good-by to Shay before surgery, I was struck by their deep bond. "It's just the two of us," he confided, his face buried in the soft ruff of Shay's neck. "I have a cabin in the woods. It's just him and me." As I led the reluctant dog away, the big golden went obediently but kept glancing back at his dad every few steps until we reached the end of the corridor and turned the corner out of sight. Several hours later I had to walk back down that same corridor alongside one of the surgeons to where the young man sat, tensely, in the waiting room. "The tumor is much more extensive than anticipated," the doctor said gently, going on to explain the gravity of the situation. The mass extended between many ribs, invading the pleural cavity, and the diaphragm muscles. There was no way to remove it all. They could "de-bulk" it but they believed this was a rare liposarcoma, a malignant cancer that would continue to grow rapidly inside the chest. The young man sat, stunned by the news. With gentle prodding by the surgeon, the decision was made to euthanize Shay. I was as shocked as the owner. How could this be? It was supposed to be just a lipoma. Lipomas weren't supposed to kill. The memory of Shay stayed with me as I contemplated Jack's surgery. "Maybe you should see a specialist," I offered. But Jack's owners opted to have me proceed.
When the day of surgery arrived, we planned to remove and biopsy several growths. "Let's start with the big one," I instructed my assistant. Once Jack was anesthetized and prepped, I made a long incision over the top of Jill. The surface of the growth peeled away easily from the overlying skin. So far, so good. Now for the underside. Not so good. Fingers of fatty tissue extended everywhere. Separating layers of muscle and fascia, the greasy mass pulled apart in my hands, my gloves slick with glistening oil. Large blood vessels branched through the deep portions of the tumor. I cautiously dissected and removed chunk after chunk of fat. It was impossible to separate the amorphous tumor cleanly from the muscle and connective tissue. After a long time, I finally stopped. "That's all I can remove without risking doing harm," I sighed. After closing the site, I excised the other growths, all of which popped out easily.
The pathologist confirmed the smaller masses were lipomas, benign tumors of normal fat tissue. Excision should be curative, although Jack will likely grow others. Jill was confirmed as an "infiltrative lipoma" with the following comment: "Infiltrative lipomas are diffusely infiltrative tumors involving the subcutis, fascia and skeletal muscle... [they] are difficult to completely remove because of their infiltrative nature. Local recurrence following surgery is common but may take several months to more than a year." The good news is that Jill was not a malignant liposarcoma. Yes, she will probably regrow - very slowly - but she will not metastasize to other places or become life threatening.
Jack has been temporarily confined to the house while his incisions heal (sans vinegar and brown paper), but he should have many happy years ahead of going up the hill, with or without Jill.
