Differential diagnosis

Two years ago, i.e. last Tuesday, November 6, we went back to the UM Cancer Center to get my diagnosis.

Blessedly, we didn't wait long.

In came Dr. F, Dr. A's assistant: 35-ish, smart, warm, pretty, cheerful without pretense. Under other circumstances it might be a pleasure to know her. The previous week she'd corkscrewed two fat needles deep into my upper left hipbone, a total of five times, digging out bone marrow samples.

About the bone marrow biopsy: she'd said it would feel like dental work. That was about right. First lidocaine, a snake of fire under the skin, then into the bone itself. Then a few minutes later the big needles. Heavy pressure; grinding noises via bone conduction. Dr. F said she'd do one core and one aspiration (sucking out fluid), but the aspiration didn't work. After three tries, she took a second core instead. On her way out, Gabrielle asked her whether the failed aspiration meant anything. Dr. F replied, "Sometimes it does mean something, but usually it's just a fluke." Sometimes it does mean something — I kept hearing that in my head all week, especially after I found the web pages about hairy cell. Fibrous bone marrow, difficult to aspirate. This can't be me. This isn't happening.

She shook my hand, sat down quickly, said "Take a deep breath, but don't worry." (Don't worry?!?) "It's not what you think. You have leukemia, but it's hairy cell leukemia. That's the good kind." The good kind?!? This is CANCER, you witch... "It's very treatable. It's not life-threatening in the short term. Cure rates are very high. 80, even 90 percent."

I don't remember much of what happened after that. Dr. A came in and confirmed what Dr. F had said. My first question — the basic question I build my life around — was how do you know? If you've watched a lot of House, TV's genius doctor from hell, you've heard about differential diagnosis: how doctors tell one disease from another, really really similar one. Not science; art. They do a lot of shooting in the dark, then turning the lights on to see what they hit. If they hit anything.

For HCL, they use several techniques. (I've probably got some of this wrong.) First there's flow cytometry, in which a laser scanner detects refraction patterns from the cell surfaces, looking for protein markers. Next there's visual inspection, under a microscope, looking at the cell morphology. That's where "hairy cell" (see the picture) gets its name: the cells have teeny little hairs, so they bind together into a fibrous mass. (That's why Dr. F couldn't get an aspirate.) Then there's clinical presentation: symptoms. Pancytopenia, i.e. low blood count in all cell lines, is typical, and that makes HCL unlike all other leukemias. Most people with HCL also have an enlarged spleen, often massively enlarged and painful, or enlarged lymph nodes, or both. Finally, certain sequences in the lymphocyte DNA can help determine which type they are. But ultimately it's the hematologist's judgment, based on experience. Better pray he's right.

Hairy cell leukemia (HCL) is rare. Very rare. Out of over 44,000 cases of leukemia diagnosed each year in the United States, only about 600 are HCL. That's about 1.2% of an already rare cancer.

And my case isn't normal. For one thing, my hairy little bastards are expressing protein CD10. This only happens in 10-15% of HCL. For another, even though virtually all HCL cases involve spleen enlargement, I don't have an enlarged spleen or lymph nodes, except for one very slightly enlarged node under my left arm. We're still waiting on the DNA tests that may (or may not) show other markers. On Friday night I'll have a CT scan, which might pick up spleen or lymph node enlargement the doctors can't feel with their hands. Yahoo. (What are you doing this Friday night?)

So I'm an atypical case of a rare disease, if they're even right about what I have. Maybe 60-80 people per year get exactly the version (cell protein expression) that I have. Maybe half that number get exactly my symptoms (or lack thereof). Maybe.

The statistics I hoped would save me — ...usually you get what most people get. Must be hepatitis C, like 3 million other Americans... — run against me now. It's hard to get enough data on typical HCL patients to build good statistics. So where do I stand?

I'm on my own out here, drifting in the current and looking for land.