HUMAN PATHOLOGY
Lecture summary - all themes
Saskia Cornet
LEIDEN UNIVERSITY LUMC Biomedical sciences year 2
,Introducing pathology
Pathology is defined as the study of disease, trough the study of functional and structural changes in
cells, tissues and organs that cause disease. It is used for the diagnosis of disease, using
morphological, immunological and molecular technics and it contributes to therapeutic options for
patients.
Several aspects of disease form the core of pathology:
- Etiology cause
- pathogenesis mechanism of development
- morphologic and molecular changes structural
alterations induced in cells and organs
- clinical significance relation to the clinical
picture
Diagnostic techniques
Biopsies are often performed in the diagnostic process.
Virtually any organ can be biopsied.
Organs can also be partially or completely removed either
as a method of diagnosis or treatment.
Intraoperative diagnosis can be a way to discover further abnormalities during an operation. The
tissue in question can be deep frozen and can into frozen sections to be stained and further
diagnosed. A drawback is the poor quality of the tissue, making the diagnosis not completely reliable.
Macroscopy can be used for diagnosing tissues. The tissue is embedded in paraffin wax making tissue
blocks which v=can be cut and stained. This can then be studied under the microscope. A microscopic
description is made from which a diagnosis is drawn. The standard staining used is HE, but
sometimes these don’t suffice, and special stains are used like: Histochemical stains or
immunohistochemical stains. Sometimes even molecular assays and electron microscopy is used.
Cytology is the process of observing loose cells. Exfoliative cytology is the study of cells that are
naturally shed through for example urine or sputum, these can often be used for diagnosis. Cells
from for example tumours can also be gathered through the use of fine needle aspiration.
Molecular pathology is another method of diagnosis. This can be done via in situ hybridization to
identify amplified or translocated genes. Alternatively, sequencing can be used to identify specific
mutations, amplifications, fusion, deletions etc. within two weeks this gives a specific diagnosis.
Every type of tumour has a specific classification and thereby a specifically targeted therapy can be
s=chosen. Some of these can be very expensive in the case of extreme rarity. In the end a diagnosis is
defined through multidisciplinary meetings.
Autopsies can have several different reasons behind them.
- Diagnostic
o Verifying cause of death in the case of sudden death
o unable to make diagnosis during life (Alzheimer, ALS etc.)
- Determine reliability of diagnostic procedure
- Evaluate effectiveness of treatment
o Beneficial or adverse effects
o Surgery
, - Training of doctors
Theme 1a. Cellular pathology and inflammation
Cell adaptation
Normal cells are in homeostasis with themselves and the environment. However, in the case of stress
on the cell or injury these cells can get harmed. Mostly these cells can adapt through influencing
themselves, or the environment, but sometimes they undergo irreversible damage, and the cell must
go into cell death.
Cells can get injured in several ways
- Physical agents (heat, cold, radiation, trauma)
- Oxygen deprivation (hypoxia, ischemia) > anaerobic glycolysis
- Chemical agents and drugs
- Infectious agents
- Immunologic reactions
- Genetic derangements
- Nutritional imbalances
An example of cell adaption can be found in the cardiomyocytes of the heart. If a part of the heart
does not function anymore, the cells must adapt, and they undergo hypertrophy (enlarge). Other
adaptations are:
- Hypertrophy (increase in cell size)
- atrophy (decrease in cell size and number)
- Metaplasia (cells differentiating to other cells (reversable))
- Hyperplasia (Increase of cell number)
- Cell death
o Necrosis
o Apoptosis
o Autophagy
These adaptation types can be classified as either reversable like hyperplasia or irreversible like
necrosis.
There are several types of necrosis:
- Coagulative
- Liquefactive = colliquative > pus
- Gangrenous > looks like mummified tissue
