Meet the doctors of sleep, images, and microscopes
In fact, it's not quite that simple. The palette can be much broader--there are hundreds of ways to stain cells to help distinguish diseases--and some pathologists use chemistry rather than microscopes to make their diagnoses. But whether tracking blood-chemistry changes on a computer printout or scanning colorful microscope slides for signs of disease, the pathologist's eyes rarely encounter a patient's face.
Hidden from view. Long considered "the doctor's doctors," pathologists are perhaps the medical specialists most hidden from public view, yet almost all hospital visits include their input. "Other physicians decide when it is worth it" to biopsy a tumor, says Tristram Parslow, pathology chair at Emory University in Atlanta. "But the only way to make a cancer diagnosis is for a pathologist to look at it under a microscope." At Emory's network of hospitals, Parslow says, that means some 250,000 colored microscope slides each year--and more than 3 million urinalyses and other chemical tests.
The process starts when a physician orders a tissue sample. Although some pathologists take their own tiny samples of a few cells using a technique called fine needle aspiration--a rare case of direct patient contact--most biopsies are done by surgeons. Then, says Sharon Weiss, director of anatomic pathology at Emory, it's "straight to the gross room," named not for the abundance of bits and pieces of the ill but for gross anatomy--the naked-eye description of the tissue--before being passed along for microscopic inspection. In the histology lab next door, specialized technicians like Kimberly Brown prepare specimens for the microscope. They start by embedding the tissue in paraffin, a wax used in canning fruit, and with a microtome--too similar to a deli counter meat slicer for the squeamish to contemplate--they shave off a ribbon of tissue just a few cell layers thick. An automated gizmo stains and mounts the specimens on microscope slides. Brown and her colleagues can process 500 to 700 specimens a day.
Deft interpreters. That's where the automation ends. "People think that you just feed a biopsy into a machine, and you get your diagnosis," says Weiss. "But it's a person who decides whether there's disease present." That work is done in a warren of "sign out" rooms (named for the pathologist's signature taking responsibility for the final diagnosis), where Emory's three dozen anatomical pathologists can be found working with nothing but microscopes and notepads, just as pathologists have done since German doctor Rudolf Virchow first turned a microscope to the study of disease in the mid-19th century. Basing their work not on quantitative tests but on years of experience, they interpret the slides, making thumbs-up and thumbs-down decisions that can spell the difference between chemotherapy and a clean bill of health.
If the specimens are cut and dried, interpreting them often is anything but. "To misdiagnose has severe consequences," says Weiss with calm understatement, "so the desire to get a second opinion is high." An expert in diagnosing rare soft-tissue cancers, Weiss says her typical day includes "about 20 jaw-breakingly hard cases from around the country." Emory's pathologists literally put their heads together over especially difficult cases, using a multiheaded microscope that lets a dozen doctors and residents peer simultaneously at a specimen. "Pathologists can differ in their opinions," says Weiss, so group sessions and second opinions are "a very important part of quality control."