How pathologists make a diagnosis
How a diagnosis is made from tissue, cells and the whole body: the kinds of sample, how tissue becomes a stained slide, how a pathologist reads it against normal structure, and the extra stains and tests that classify disease.
By the end, you can
- Compare cytology, biopsy, resection and autopsy, and what each can and cannot show.
- Explain each step that turns fresh tissue into an H&E-stained slide, and why it is needed.
- Describe how a pathologist reads architecture and cells against normal tissue.
- Match special stains, immunohistochemistry, immunofluorescence and genetic tests to the questions they answer.
- Recognise the stains, markers, artefacts and test measures (sensitivity, specificity and predictive values) examiners ask about, and explain how pathology results steer treatment.
What it is
Pathology is the study of disease through the changes it makes in organs, tissues, cells and body fluids. Histopathology diagnoses disease from tissue (biopsies, resections and autopsies) and cytopathology from cells alone; both compare the sample with normal structure and combine what they see with the clinical picture and further tests.
3 types to tell apart
- Cytology
- Cells shed, scraped, aspirated or spun from fluid. Quick and gentle, but without tissue architecture.
- Biopsy and resection
- Tissue with its architecture, from a small core to a whole organ; resections also show size, spread and margins.
- Autopsy
- Examination of the whole body after death, to establish the cause of death and the diseases present.
Normal function
The reference: normal tissue
Every judgement a pathologist makes rests on knowing what normal tissue looks like. Normal small-intestinal mucosa is a good example: tall, finger-like about three or more times as long as the are deep (the ), a lining with scattered and only a few among the epithelial cells, and a with a modest population of immune cells.
A pathologist reads three levels: the arrangement of the tissue (architecture), the appearance of individual cells and their nuclei, and anything that should not be there, such as inflammatory cells, organisms, deposits or crystals.
Underlying change · Step 1 of 5
Taking the sample
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Underlying change · Step 2 of 5
From fresh tissue to a stained slide
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 5
Reading the slide against normal
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 4 of 5
Special stains, polarised light and immunofluorescence
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 5 of 5
Proteins, cells and genes: classifying the disease
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .