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Monday, February 13, 2012

By Michelle Gerhard Jasny V.M.D.
Published: March 26, 2009

For several weeks Ketch, a cocker spaniel, had a small patch of thickened skin on her neck. Right around Christmas, the lesion began increasing in size. When it ruptured, her owner brought Ketch in for me to take a peek. The area in question was red, relatively flat but firm, with a central open sore discharging a little fluid. "She's running a low-grade fever," I said. "Could be infection or an allergic reaction to something like a spider bite." I paused. "Or it could be a tumor. We would need a biopsy to know for sure."

Her owner hesitated. "Ketch is almost 14. I don't want to put her through a lot." We agreed to treat the lesion empirically, and consider further diagnostics if it didn't resolve.

Two months later, the surface sore had healed, but what had been a small, flat lesion was now a very large, irregular mass. "It's probably cancerous," I said, sighing. The location could make surgery difficult, with all the blood vessels and nerves that run close to the neck's surface. On the other hand, the lump felt well circumscribed and not attached to the underlying structures. "We could remove it surgically," I offered. "Either here or by referral to a specialist."

Ketch's owner hesitated. What was the long-term prognosis? Would she also need chemotherapy or radiation? Did that make sense considering Ketch's age?

"For some types of cancer, surgery can be curative," I continued. "But it makes sense to gather more information before proceeding." I suggested getting a small biopsy using a local anesthetic. With a definitive diagnosis, we could make an informed decision about our next steps. It was Tuesday. I had a light schedule. "We could take the sample today," I offered. "The sooner we get an answer, the better."

"I need to go away in a few days," the owner responded. "Will that be a problem?" I assured her complications were rare as I walked her to the door.

Once Mom had left, I prepped the lump and injected a local anesthetic. I made a tiny nick with a scalpel, then inserted a Tru-Cut Needle into the mass. Unlike a "fine needle aspirate," which sucks a few cells out via hypodermic needle, the Tru-Cut Needle actually cuts a little tissue core, preserving the architecture. These biopsies are much more accurate than aspirates.

My first attempt yielded nothing but blood. "Hmmm, pretty vascular," I muttered and tried again. My third attempt yielded a decent sample. A drop of blood bubbled from the incision. I applied pressure. Blood continued to well up slowly. I packed the area with special hemostatic surgical material. No more bleeding. One suture and we were done. Ketch stayed the rest of the day for observation. I released her as we closed for the evening, her tail wagging happily. I was in a good mood, too - happy we had moved promptly toward definitive diagnosis - and happy tomorrow was my day off. My 11-year-old and I were taking an early morning ferry for a long-awaited mother-daughter outing.

Our Wednesday trip was a huge success. We went to Build-A-Bear, bought new clothes, ate Chinese food. My daughter actually talked to me. We took a late boat home.

The next morning, I awoke early and went into the office, as I often do, to organize my day. A fax from the night before sat in the machine. I read the report, sitting down slowly in dismay. Ketch had been fine all night Tuesday but on Wednesday morning had started to bleed again - a lot. The veterinarian on emergency call ran tests and treated her with fluids, medications, and bandages. Ketch began having seizures. It was suggested she go immediately to a 24-hour emergency facility with an ICU and specialists on staff, but in keeping with her earlier decision not to pursue "heroics," Ketch's mom opted to take her dog home for the night and hope for the best. I glanced at the clock as I finished reading - not yet 7 am. I decided to wait a few hours before calling for an update.

But Ketch's owner called me as soon as my office opened. The elderly Cocker had died overnight. We talked for a while. What could have happened? This must have been something nasty to have such a dramatic complication from such a minor procedure. I expressed my condolences, and then hung up, deeply shaken.

What went wrong? Could I have nicked a large vessel like the jugular? Highly unlikely. What else could explain this unexpected turn of events? I knew that a kind of neoplasia called mast cell cancer (MCC) can sometimes release histamine after a biopsy, resulting in a massive allergic reaction. If there is a high suspicion of MCC, I pre-treat with anti-histamines (though the usefulness of this is controversial). This had not been high on my differential list for Ketch.

Researching similar cases, I read about circumstances in which MCC may also release heparin-like substances, in other words, anticoagulants. This can lead to a clotting disorder called Disseminated Intravascular Coagulation (DIC), with severe, even fatal hemorrhage. The more I read, the clearer it became. This was probably what happened to Ketch. Three days later, the pathologist confirmed the diagnosis of mast cell cancer.

It isn't always easy to know the right path to take in medicine. The first rule is: Do no harm. Should we ignore possible cancer? No. That may do harm. We needed to know what the lump was, to make a treatment plan. Should we act as though every biopsy patient is going to have this rare complication? No. That's neither medically appropriate nor financially realistic. The risk-to-benefit ratio in the overwhelming majority of cases supports taking these types of biopsies. My lesson, once again, is to be as vigilant as I can about every "What If?" with every biopsy. Ketch's mom was sad, but tenderly resigned, recognizing that, considering the final diagnosis, the ultimate outcome would likely have been the same no matter how we had chosen to proceed. It had just been the little dog's time to sail off into the sunset.