Pathology (from Greek pathos (πάθος) = experience or suffering and -logia (-λογία) = study of) plays a significant role in modern medical diagnosis and medical research. Pathologists identify the nature of abnormal tissue and/or cells. If they find that a sample is malignant, they provide evidence to the clinician on the type of cancer, its grade and, for some cancers, the likely profile of responsiveness to certain treatments.

However, pathology is a largely unknown field in medicine. Often, pathologists are depicted as working on their own in a lab without interaction with patients or colleagues. Dr José Cândido Xavier Jr., a specialist in surgical, dermato- and cytopathology, decided that it is time to set the record straight. This is the first part of our series “The Role of a Pathologist in Diagnosis and Treatment”.

Pathologists are physicians who perform their work behind the scenes. Their specialties vary widely. Some are university professors and researchers, others might work as forensic specialists in law enforcement. Most commonly, they diagnose diseases at public or private laboratories. Basically, pathologists spend most of their time analyzing microscope slides in order to provide diagnosis, whenever it is feasible.

Sometimes the microscopic diagnosis is straightforward; however, sometimes pathologists spend hours studying unusual cases. Until a final diagnosis is made, a pathologist might ask for additional slides or use special stains that are contained in blocks of wax (see below) to identify fungi, bacteria, or substances such as amyloid. Amyloid is a type of protein. There is one disease called amyloidosis caused by its deposition in our tissue. So, it is important to recognize amyloid in the slides.

Usually, pathological diagnosis is based on a stain called Hematoxylin and Eosin (H&E). In specific situations, e.g. when looking for fungi or bacteria, pathologists additionally use the above-mentioned special stains (Alcian Blue, Silver Stain, Fite-Faraco, Mucicarmine, etc.).

There is a misconception about pathologists’ lives. Many people believe that pathologists work alone and do not interact with patients. In fact, pathologists perform procedures on patients, such as fine needle aspiration, in order to obtain tissue and cytological samples.

These may be brief interactions, but they are meaningful. Pathologists remain connected with the hospital team at all times. Interactions also occur at clinical meetings or tumor board reunions and consultations by phone calls or smartphone applications. There are some cancer-related emergencies in which the pathology report is decisive for treating patients. Patients must often wait for pathology reports to begin cancer treatments.

Even inside the laboratory, pathologists are not alone; they work in teams with other pathologists, with physician assistants, biologists, and other health professionals. Another misconception is that pathologists only diagnose cancer. In fact, they do diagnose infections and inflammatory diseases. Lupus, dermatomyositis, tuberculosis, and leprosy are just a few examples of inflammatory and infectious diseases diagnosed based on pathology reports.

A unique aspect of pathology are the step-by-step procedures to transform biopsies, surgical specimens, or body fluids into microscope slides. When samples arrive at a laboratory, they are processed according to international scientific-based guidelines. The tissue specimens are fixed in substances like formalin to aid visualization with a microscope. However, observing a raw tissue sample can provide valuable information for the final diagnosis. After processing using machines (or histology tissue processors), tissue samples can be embedded in paraffin. The blocks of wax containing the samples are sectioned and stained to make the microscopic visualization possible. Then, the microscopic interpretation of the tissue and cell morphology (analysis of the shape, structure, form, and size of cells) will start.

Pathology is the specialty sought by physicians who enjoy integrating basic science with clinical practice. Pathology is the art of seeing what appears to be invisible at first glance. Dr Richard J. Reed (1928–2021), a brilliant pathologist, once wrote that “the ability to integrate microscopic findings into a meaningful interpretation is the distinguishing characteristic of a pathologist and is the art of pathology”.

In order to become a pathologist, a new medical school graduate attends a residency that lasts 3–6 years. Nowadays, the application of artificial intelligence and virtual pathology has been helping to provide faster and more accurate diagnoses. Despite the increasing incidence of cancer, the number of pathologists worldwide is relatively small, making pathology an excellent specialty considering the quality of life and career advancement. Unfortunately, most student physicians do not discover this jewel of medicine.

Illustrations from “Fast Facts for Patients and Their Supporters: Advanced Cutaneous Squamous Cell Carcinoma” by Dr Sarah T Arron, S. Karger Publishers Limited, 2019.