Emergency pathology

Author: Mikael Häggström
This article is written specifically for new pathology trainees.

Memorization-worthy: Information relating to emergent pathology is often not conveniently and timely looked up when needed because of the need for a fast report.

Comprehensiveness

On this resource, the following formatting is used for comprehensiveness:

• Minimal depth
• (Moderate depth)
• ((Comprehensive))

Frozen sections

Even new pathology trainees may end up being the first responders to frozen sections (as well as intraoperative consultations by gross inspection only).

Preparation

Prepare at least the following:

• Finding out which senior to call for help if responding to a frozen section. A fairly new pathology trainee should generally not independently make a report to the referring physician without having at least consulted with a senior, and therefore the diagnostics of frozen section slides is not included in this section. In the meantime, ensure that you have a working smartphone available, and know beforehand who to contact whenever you are at risk of being responsible for a frozen section, so that you can perform micrography of the slide in case and send it to the senior if that person can not be physically present within an acceptable time.

• 
  To perform micrography with a smartphone, stabilize the smartphone over the eyepiece (preferably using both hands), about 3-5 cm away from it, and direct it on the bright circle on your phone display...
• 
  ...and then slowly move the smartphone closer to the eyepiece, while adjusting both direction and location so as to keep the bright circle in the center of the display, until the camera is able to focus and you have a visible field that is large enough for evaluation, and then take your photos.

File:Metastasis sites for common cancers.svg

Main sites of metastases for some common cancer types. Primary cancers are denoted by "...cancer" and their main metastasis sites are denoted by "...metastases".

• If possible, look up pertinent medical histories of potential cases that may appear as frozen sections or other forms of intraoperative consultations. For example, surgery departments may have schedules of patients for the day that you will cover frozen sections. On such lists, types of surgeries that often come as intraoperative consultations mainly include potentially malignant skin excisions, lung excisions (larger than biopsies), ovarian tumors, and samples from other common metastasis sites (lungs, liver, brain, bone). The most important details to find out are:

• What you may do yourself if you will be alone when you get the specimen, or if you need to wait for particular seniors before doing potentially irreversible steps such as inking and sectioning.
• Previous biopsies. For expected excisions from common metastasis sites, look thoroughly for any past cancer diagnoses. Note the pathologic diagnoses of the biopsies((, as well as the collection dates and accession numbers.))
• Tumor sizes where applicable(, and whether the estimation was from imaging or microscopy).

• Make sure you have a working microtome. Switch its blade if you are not certain it has had limited use.
• Prepare at least as many chucks as you think you will need according to any surgery schedule (or at least 3 of preferably various sizes).

• You can theoretically put a specimen directly on the chuck plate, but to reduce the risk of tearing, put embedding medium on empty chucks
  You can theoretically put a specimen directly on the chuck plate, but to reduce the risk of tearing, put embedding medium on empty chucks
• Wait until the embedding medium is frozen at the bottom
  Wait until the embedding medium is frozen at the bottom
• In the meantime, you should smear some oil on the bottom of a conductor, to avoid it getting stuck to the specimen later.
  In the meantime, you should smear some oil on the bottom of a conductor, to avoid it getting stuck to the specimen later.
• Place the conductor on top of the chuck. You now have a prepared chuck with a smooth surface.
  Place the conductor on top of the chuck. You now have a prepared chuck with a smooth surface.

(If you don't have a conductor, or if the embedding medium completely hardened before you applied it, perform cryotomy of the embedding medium to get a larger and smoother top.)

• Inspect the H&E staining containers and refill if necessary.

• Example of material needed for H&E staining of frozen sections: Staining fluids, glass slides, pencil to mark slides (the ink of pens will generally be washed off in the fluids), slide dipper, timer, cover slips and immersion oil.
  Example of material needed for H&E staining of frozen sections: Staining fluids, glass slides, pencil to mark slides (the ink of pens will generally be washed off in the fluids), slide dipper, timer, cover slips and immersion oil.

• Ensure that you have frozen section medium, as well as cover slips and mounting fluid.

Performing frozen sectioning

• Inform relevant seniors.
• Look at any requisition form or otherwise check or confirm what answers the requesting clinician wants. When the histopathologic type of tumor is known from before and its distance to the closest margin is relatively far, a gross intraoperative consultation is generally enough to measure that distance.
• Measure the size of the specimen.
• If you are permitted to proceed with the following steps, which are potentially irreversible, still consider whether there are any surprising aspects that requires you to wait until a senior arrives.
• Ink relevant margins
• 'Section the specimen so as to be able to see relevant pathologies, and closest distances to relevant margins.
• Select tissue to be able to answer the clinician's questions.
• Trim samples to make them equally thick, since you will need to section away more from thick pieces before thinner pieces will appear in cryotomy slices.

• Put specimens on one or more chucks. It's better to put it on a slightly too large chuck than a slightly too small one.
  Put specimens on one or more chucks. It's better to put it on a slightly too large chuck than a slightly too small one.
• Cover the specimen with embedding medium
  Cover the specimen with embedding medium
• Apply a conductor (unless it's a thin specimen that needs to stand on its side)
  Apply a conductor (unless it's a thin specimen that needs to stand on its side)
• Use freeze spray to quicken the freezing if available
  Use freeze spray to quicken the freezing if available
• Breaking off any embedding medium that reaches below the chuck's plate
  Breaking off any embedding medium that reaches below the chuck's plate
• Fasten the chuck on the cryotome and cut relatively thick sections until the full tissue surfaces of interest are exposed
  Fasten the chuck on the cryotome and cut relatively thick sections until the full tissue surfaces of interest are exposed
• Generally set the thickness to 5μm, and advance the specimen over the blade while holding the section down to prevent it from folding onto itself
  Generally set the thickness to 5μm, and advance the specimen over the blade while holding the section down to prevent it from folding onto itself
• Contine until all the tissue of interest is in the section
  Contine until all the tissue of interest is in the section
• Put a glass slide on the tissue
  Put a glass slide on the tissue

Suspected malignant skin excisions

While most frozen sections can be predicted from schedules of the operating room and thereby be looked up beforehand, suspected malignant skin excisions often come from outside the main surgery department, even more indicating memorization of how to handle them.

Tissue selection

Tissue selection from suspected malignant skin lesions, by lesion size:

<4 mm	4 - 8 mm	9 - 15 mm
File:Tissue selection from skin excision less than 4 mm with suspected malignant lesion.png	File:Tissue selection from skin excision 4-8 mm with suspected malignant lesion.png	File:Tissue selection from skin excision 9-15 mm with suspected malignant lesion.png

In table above, each top image shows recommended lines for cutting out slices to be submitted for further processing. Bottom image shows which side of the slice that should be put to microtomy. Dashed lines here mean that either side could be used. Further information: Gross processing of skin excisions

Other frozen sections

Although these are generally given on schedules of the operating room, any pathologist may end up suddenly covering for another one, and subsequently be presented with the frozen section case without having had the time to look it up beforehand.

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