The Sausage Trick
This technique allows you to take soft difficult to cut tissue and make it firm and easy to cut by rolling the tissue in a paper towel or absorbent pad. This technique also prevents the knife blade from dragging ink into the tissue . This works particularly well with fresh fatty breast specimens received for frozen section.
1) Dry the specimen first. To roll the tissue, use a high quality paper towel. Some of the higher quality folded towels work fine. If you only have low quality paper towels use two together and be sure to dry the tissue. If wet, these low quality towels will not firm up quite the same and shreds of paper will tear away when you go to unwrap the tissue. I find these sturdier absorbent pads to work very well.
2)Place the tissue in the center of the towel.
3) Fold the towel in half diagonally over the tissue.
4) Crimp the paper with your fingers and roll the tissue and paper tightly 1 1/2 turns.
5)Slice the tissue through the paper into slices of the desired thickness.
6)Pull back the folded corner of the paper to unroll the tissue.
7) Lay out the slices in order and orientation.
8) Thoroughly examine each slice with both eyes and fingers, from as close as your eyes will let you focus on the tissue.
As I like to tell my residents" if you cannot smell the tissue, or the formalin is not burning your eyes, your not looking close enough!
Looking at slides
When we start looking at slides as a young resident we we find ourselves peering through the microscope looking at fields of tissue one after the other with little more plan than to try and tell what tissue we are looking at and to match what we are seeing to one of the perfect examples of the entity in our texts. As we gain more experience we have cases to reflect back on, the many variations we have seen and those mistakes we have made or seen others make. I would like to offer a more structured approach to examining slides which I have found successful in helping me arrive at a correct diagnosis and avoid embarrassment. First several observations:
Observations on observation
1) You only see what you are looking for.
It is not uncommon to find myself self or others staring into a field with an obvious diagnostic finding right under our nose. If we do not look for it, often we will not see it. So if you want to be sure you have not missed something, you better look for it.
2) You can only look for one thing at a time carefully.
Example: Try screening carefully for microcalcifications in a breast specimen and at the same time be comfortable that you are not missing a microscopic focus of a near invisible invasive lobular carcinoma. I cannot do it. I typically go over the slide twice or more. I screen from 2 x which makes it go faster. If I am looking for involved nerves and lymphatics I will take a third pass this time focusing around neuro-vascular bundles.
With every slide and specimen type I have a simple plan for examining the tissue that starts with " What am I looking for and what don't I want to miss?" For example a simple gallbladder submitted for cholecystitis, I will look for the cholecystitis on my first pass, then I will make sure I do not miss the "invisible cancer" (small infiltrating tumor cells that can be very easy to miss, particularly in an inflamed background); "blue epithelium" (dysplasia); and other tiny things such as lymphatics with emboli ect. I will typically make several passes of the slide under the scope.
In many tissues it is useful to examine all of the histologic elements in an orderly fashion to compile the findings into a diagnosis. Liver, bone marrow, kidney biopsies and colitis biopsies are good examples of this.
In a biopsy for colitis I will first look at the glandular archetecture at 2x. Then move to 4x or higher and systematically look at the surface epithelium, basement membrane, glandular epithelium, inflammatory cells within the lamina propria and epithelium, look at the vasculature, look for granulomata, look at the secretions for organisms, and again come back to the lamina propria to make sure I have not missed an occult metastasis to a lymphatics or a few sneaky signet rings or a rare parasitic organism. By looking at all of the histologic elements this way I am reducing my chances to miss a diagnostic clue. It may seem like a lot of passes through the tissue but it really goes quite quickly as you are quite focused on what you are looking at.
Learning to read at 2x
It also helps to be able to recognize as many of these features as possible at 2x. You can learn to recognize even single cells at 2x simply by looking at them at higher powers and then go to scanning powers and look to see if you can recognize it. Finding Reed Sternberg cells, CMV inclusions and even a rare tumor cell in a lymph node is possible at 4x and sometimes 2x if you are looking specifically for a very tiny but recognizable structure. The better you get at seeing things at scanning power, the faster you will be able to work and the multiple passes of the slide will go quickly.
I have found that taking this organized approach to reviewing slides leaves me feeling more comfortable that I have not missed anything critical.
Struggling with the tough ones
You can only make a diagnosis if you think of it!
You can be the most well read encyclopedic mind in our field but if you are handed a slide that takes a little thought you will not make a diagnosis if you do not think of it. I teach my residents from day one to learn the broad classifications of diseases by classification and organ system. Try throwing up an imaginary chest film with a few vague findings and ask a group of young residents what is there differential diagnosis. Typically someone will say tumor or pneumonia and not much more. Now open the table of contents of Robbins and read the chapter titles. By mentioning diseases of immunity, congenital diseases, vascular diseases, occupational diseases ect. out will pop numerous possibilities that nobody thought of. They all heard of Wegoner's granulomatosis, silicosis, pulmonary emboli and numerous others but unless stimulated, you do not always think of it. If you think about the pneumonias by class then out will pop, bacteria, mycobacteria, fungi and parasites. If you think about the tumor classes numerous possibilities will come into your head not just the common ones. If all one knows is the classification and a few points about each disease, you will be stimulated to look deeper into the possibilities when confronted with the tough case.
Always start by reading the table of contents. It is the broadest outline of the disease class. Knowing only this will give you an important first step to learning and feeling comfortable with the subject.
I ask my residents at the beginning to "Label the files in there head." As they see cases they will add to these files with experience. But even as a neophyte, if for example you know the classification of salivary gland tumors and are confronted with an example you have not seen before, if you are familiar with the classification, you can go through the files in your head, cross out the ones you are sure do not fit and read on the ones that are possibilities. You will have a familiarity with the subject that leaves you with the comfort that you thought of most of the possibilities. Compare this to reading the same slide and only knowing the names of four of the twenty or more possibilities. You will feel quite insecure.
As a resident, I kept a list of "Things to think about when your stuck". I encourage my residents to keep a similar list and add to it. Of course on the top of this list is the the king of the monkeys, malignant melanoma. Melanomas can show up anywhere and mimic just about anything. It is an easy diagnosis to make.....if you think about it! On this list should also be diagnoses you will never make without thinking about it. Good examples of these are histiocytosis, mastocytosis and hairy cell leukemia in the marrow, demyelinating pseudotumor in the CNS, amyloidosis and many many more. On this list should be germ cell tumors, myeloma, renal cell carcinoma, granulocytic sarcoma, thymoma, mesothelioma, sarcomatoid carcinomas and, epithelioid sarcomas, all things that you can miss if seen outside their element as an occult met or mass.
There are many types of "tough ones" Probably the most common example is a miserable crushed, burned or fragmented example of something that would be easy if you had a good sample. This can be something as simple as a colon polyp or as tough as calling dysplasia in a Barretts. Here the best we can do is cut a bunch of levels and get the opinion of a colleague. The more exiting "tough ones" are the good examples of things we have never seen before. This may be a rare tumor type or disease state, or more commonly an uncommon variation of something more familiar to us. Be aware that many tumors can have numerous variations that overlap with different entities. Just think of the variety of patterns that can be seen in mesothelioma, menengioma, and melanoma. If we at least think of the possiblities we can use our immuno stains to help sort it out.
When faced with very high grade anaplastic tumors often if we look hard enough these tumors will tell us secrets in the form of subtle differentiation. A little melanin, bile, lipoblasts, osteoid, mucin, a rare gland ect. The point is if we think about it and look for it patiently we are sometimes rewarded.
Study the obvious examples to learn the subtleties
If you want to learn to recognize gastric dysplasia look at the premalignant changes adjacent to the obvious cancers. There will often be beautiful examples of these early changes which will offer a wealth of learning material. Say to your self, what would I call this on a biopsy. You will see things that are clearly dysplastic and subtle things that you would hedge on in a biopsy but are sure is dysplasia in the context of this large display. Look at the neighboring glands in a endocervical adenocarcinoma. You will see things you would only call atypia in a biopsy but seeing in in context will convince you that it is extremely early dysplastic change. Look at the ducts in a pancreatic cancer you will see a spectrum of early changes. These big resection specimens are often full of examples of early neoplasia which are more valuable learning material than recognizing the obvious cancer. And when faced with that miserable biopsy you will have good examples of what is and is not tucked away in the files in you mind.
To be continued.......