It is common in the field of pathology that one pathologist is not certain of a diagnosis. The pathologist is the type of doctor that reads the slides I prepare in the histology lab. They can look at the slide and usually they can see what is wrong with the patient. They can tell if the patient has cancer, what type of cancer, if their sickness is caused by an immune response, or if they have an infection.

Sometimes they see the specimen on the slide isn’t normal but they can’t tell what it is. The disease appears like several diseases at once or the specimen might not be prepared well enough by the lab. The lab might have made ‘artifacts’ on the slides that look like a disease or obscure a disease.

In difficult to diagnoses cases the lab is usually asked to run extra stains on the specimen. More slides are cut and instead of them being stained with H+E they are stained with special stains to show if certain disease processes are present.

From Slideshare; this image shows how Ki67 and other stains are used to subtype breast cancer.

For example, cancer cells divide faster than normal cells. You can see the cells are dividing when you look at them on an H+E but not all of them. They look different depending on what point they are at in their division process. KI-67 is a stain that will highlight all cells that are dividing. It will make them stand out so the pathologist can see if there really are more cells dividing than normal, which would be cancer.

The KI-67, or any other stain, might give a clue but not show exactly what type of cancer. More stains can do that or someone with more experience.

When a pathologist isn’t sure how to diagnose the case, they will seek a consultation with another pathologist.

A two headed microscope.

Going to another pathologist is called a ‘consult’ in short. Sometimes the original pathologist simply walks the slide over to his colleague’s office. This would be a pathologist with more experience with the type of cancer the first pathologist suspects is present. They can look at the slide together on a multi-headed microscope and they can discuss what they see.

H+E of breast cancer. Photo by Ed Uthman, Wikimedia Commons.

If the two of them cannot decide on the diagnosis, there are other types of consultations.

The case might be brought to a Tumor Board where a group of pathologists will look at the H+Es and special stained slides and decide on a diagnosis together. If a Tumor Board isn’t available, the case can be sent out to another institution for a consult.

Many sent out consult cases originate from small hospitals. They might not have groups of pathologists who can form a Tumor Board. They may only have a few colleagues working with them and none of them know how to diagnose the disease. It is also possible the pathologists don’t have the techs or equipment to do the special stains for them. Not all labs do all special stains. In that case, they will send the case out.

The lab will cut the slides required or gather the blocks and reports and send them through the mail to whatever institution their pathologist chooses.usps-796059_1920 Occasionally, a patient will come into the lab and  pick up the slides and take them to the new institution. Whichever the case, the slides are sent and within a few weeks the consulting pathologists will return a report.

It’s as simple as that. Slides and blocks are sent through the mail all of the time. Dozens of them come to my hospital every day. So if you ever learn your case was sent out for ‘consult’ it means nothing more than more doctors looked at it to make sure they diagnosed you correctly.

If you would like to know a little more about this process, here is a blog post that covers who pays for consults and how pathologists choose who to consult.


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