The ultimate judge of disease diagnosis——pathology

Author: Fan Ruirui, PhD, Xiang'an Hospital Affiliated to Xiamen University

Reviewer: Gao Jie, deputy chief physician of Xiamen Hongai Hospital

As patients or their families, you may have limited knowledge of complex medical knowledge such as how clinicians determine whether a tumor is benign or malignant, how to classify, grade, and stage it, and how to assess whether the tumor has been completely removed. In order to diagnose and treat patients more accurately, in addition to relying on the professional skills of clinicians, you also need to rely on the pathology department! However, since the doctors and technicians in the pathology department mainly deal with tissue samples and do not communicate directly with patients or their families, the pathology department may not be well known to the public.

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"Doctor, I want to go to the pathology department. Excuse me, is the pathology department the place where urine tests are done?" "No, that place is called the laboratory department. The pathology department is responsible for disease diagnosis." In fact, there are essential differences between the pathology department and the laboratory department in many aspects, such as professional requirements, qualifications requirements for review report personnel, types of specimens received, and testing purposes.

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The Pathology Department is an important department that is indispensable for disease diagnosis and guiding clinical treatment. Its core work is to issue professional and rigorous pathology reports for patients. Pathology diagnosis is currently recognized by the medical community as the "gold standard" for tumor diagnosis. It is like a "judge", shouldering the important task of "judging the benign or malignant nature of the disease" and "the most reliable basis for formulating individualized treatment plans for patients." Therefore, pathologists are also known as "doctors' doctors." Next, let's go deep into the Pathology Department and understand the rigorous and meticulous work process!

1. Specimen Receiving and Sampling

Specimen reception and sampling are the primary links in the workflow of the pathology department. The pathology department receives a variety of specimens sent from the operating room every day. When receiving these specimens, the principle of "three checks and seven comparisons" must be implemented to check the patient's name, age, gender, hospitalization information, specimen name, specimen location, specimen quantity and other important information to avoid misidentification. However, whether it is a complete diseased organ or a complex diseased tissue, the pathologist will accurately find the location of the lesion through careful examination. Subsequently, the pathologist will accurately cut the diseased tissue into "meat pieces" of uniform size, which we usually call "tissue sample blocks". These "tissue sample blocks" must include the deepest infiltration and the surrounding normal tissues to ensure the comprehensiveness of the diagnosis. Their number is usually close to the maximum diameter of the lesion, and the size is usually about 1.5cm×1.5cm×0.3cm.

2. Production

The process of pathological slide preparation is complex and delicate. It aims to make the removed tissue samples into thin slices that are convenient for microscopic observation through a series of processing steps, so as to make pathological diagnosis.

1. Soak the removed tissues in 70%, 80%, 90%, 95%, and 100% gradient alcohol and xylene overnight to remove moisture from the tissues and make them transparent;

2. Embed the dehydrated tissue in paraffin and make it into tissue wax blocks;

3. After a series of complicated processes such as slicing, scooping, drying, staining, and neutral resin sealing, tissue sections with a thickness of 3 to 5 μm are made.

These pathological sections look similar to the mutton rolls we usually eat, but they are much thinner than mutton rolls, as thin as a cicada's wing!

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3. Reading films under a microscope

When the pathologists deliver the well-made tissue sections to the pathologists, the doctors carefully observe every cell on the tissue sections to find the "clues" between the cells. When encountering difficult problems, several pathologists will sit together under a multi-head microscope to read the sections and brainstorm to ensure the accuracy of the diagnosis.

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4. Issuing a pathology report

From bags of specimens to "gorgeous" pathological sections, the "eagle eyes" of pathologists, based on the tissue morphology under the microscope, combined with immunohistochemistry and molecular detection and other technologies, ultimately form a pathological diagnosis. However, a complete pathology report is more than that. It needs to be initially diagnosed by a junior pathologist and then reviewed by a senior pathologist. This pathology report describes in detail the patient's basic information, specimen information, gross and microscopic images, microscopic morphology and disease diagnosis. Disease diagnosis includes: gross classification of tumors, histological classification, histological grading, pTNM staging, tumor range, depth of infiltration, whether there is neurovascular invasion, and whether the resection margin is clean.

In short, although the pathology department is not yet widely known, pathological diagnosis not only plays a vital role in the diagnosis and treatment of patients' diseases, but is also closely related to the overall medical level and quality of the hospital. It can be called the ultimate "judge" of disease diagnosis!