Pathology

Pathology is the branch of medicine that studies the causes and effects of disease, focusing on structural and biochemical changes in tissues and cells. It aims to understand disease processes and translate findings into diagnoses, prognoses, and treatment guidance. Pathology serves as a bridge between basic science and clinical care, using laboratory analysis, tissue examination, and autopsy to characterize illness.

Pathology is divided into anatomic pathology and clinical pathology. Anatomic pathology analyzes tissues and organs to establish diagnoses, often from biopsies or surgical specimens. It includes histopathology, which examines tissue architecture under the microscope, and cytopathology, which evaluates individual cells or cell clusters, such as in cytology smears or fine-needle aspirates. Clinical pathology, also called laboratory medicine, focuses on laboratory analysis of body fluids and other specimens, and encompasses specialties such as clinical biochemistry, hematology, microbiology, immunology, transfusion medicine, and molecular pathology.

Techniques common to pathology include light microscopy with various stains, immunohistochemistry, flow cytometry, cytogenetics, and molecular diagnostics such as PCR and sequencing. Advances in image analysis and molecular profiling increasingly support personalized medicine and targeted therapies. Quality assurance, standardization, and laboratory accreditation are essential components of pathology practice.

Pathology plays a central role in disease diagnosis, prognosis, and the selection and monitoring of therapy. It also covers forensic pathology, which determines cause and manner of death, and contributes to biomedical research and education. The discipline has a long history, with foundational developments in cellular pathology attributed to Rudolf Virchow in the 19th century.