What is pathology?

The term ‘Pathology’ is derived from two Greek words (pathos) meaning disease, and (logy) which means study. Pathology is, thus a branch of biological sciences that deals with the study of all structural, biochemical and functional changes and abnormalities in cells, tissues, and organs that take place as result of a disease.

Pathologists are the diagnosticians of these abnormalities and diseases. Pathology is the link between the basic sciences and clinical sciences, and is the scientific foundation for all of medicine.

History of Pathology

The understanding of histopathology began when Rudolf Virchow (1821–1905) a German scientist who started with the beginning of microscopic examination of diseased tissue at cellular level. Virchow gave two hypotheses:

1. All cells come from other cells.
2. Disease is an alteration of normal structure and function of the cells.

Pathology divisions

Human pathology is divided into:

1. General Pathology: dealing with study of common basic changes in all tissues.
2. Systemic Pathology: that includes study of diseases in tissue or organs of a particular system.

Specialties of Pathology

Pathology include the following subspecialities:

1. Anatomic pathology, is the study which includes structural changes observed by naked eye examination referred to as gross or macroscopic changes. Anatomic pathology includes 3 main subdivisions:
   • Surgical pathology: It deals with the study of tissue abnormalities removed from a living body.
   • Forensic pathology: This focuses on the medico-legal investigation of the cause of a sudden death by examination of a dead body.
   • Cytopathology: include the study of cellular changes.
2. Haematology, deals with the diseases of blood.
3. Chemical pathology, this branch include analysis of biochemical constituents of body fluids including: blood, urine, CSF and other body fluids.
4. Experimental pathology, is the study of diseases that have been induced experimentally.
5. Molecular pathology. Include the detection of abnormalities that take place at molecular level (DNA level).
6. Immunopathology, focuses on the study of diseases mediated by immune reactions.