Pathology As a Medical Specialty: Historical Overview

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Pathology As a Medical Specialty Historical
Overview Programmatic Summary
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WHY DID PATHOLOGY BECOME A SPECIALTY?

• Pathology evolved as a distinct specialty for the
  same reasons that Radiology, Anesthesiology, and
  other hospital-based disciplines did namely, the
  body of knowledge and technology involved in
  those areas grew beyond the ability of other
  practitioners to utilize it properly and optimally

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AIMS OF PATHOLOGY AS A DISCIPLINE

• To further our understanding of the mechanisms of
  disease, and, in so doing, allow for a more
  effective disruption of them
• To utilize existing knowledge integrating
  information from other clinical specialties,
  several biological and physical sciences as a
  means of accurately categorizing disease
  processes in the clinical sphere
• To consult with clinical colleagues in the care
  of patients so that laboratory information is
  effectively and properly integrated into
  diagnosis treatment planning in this context,
  pathologists must be knowledgeable about clinical
  findings and data from virtually all other
  specialty areas

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WHY CONSIDER THE HISTORY OF PATHOLOGY?

• Nothing gives a better perspective on a subject
  than an appreciation of the steps by which it
  reached its present state.
  --E.H. Lang

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The 19th Century Appearance of Pathology as a
Distinct Discipline in Medicine
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Infectious Disease in the 1800s the First
Successful Target of Pathology

• Revolutionary ideas on infection were presented
  in the mid- to late 1800s by Pasteur (a
  biochemist), Lister (a surgeon and surgical
  pathologist of sorts), Koch (a
  bacteriologist), which, in aggregate, were used
  to identify, prevent, and treat specific
  communicable diseases

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Virchows Cellular Theory of Disease the 1860s

• Rudolph Virchow (1821-1902) was a German
  physician who pioneered the cellular theory of
  pathology that is, disease was considered to
  represent the aggregate dysfunction of specific
  cells in any given abnormal organ.
• This concept paved the way for subcellular and
  molecular pathology of the 20th Century and beyond

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Rudolph Virchow, M.D. Originator of modern
Pathologic theory
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Virchow R Cellular Pathology--As Based Upon
Physiological and Pathological Histology.
London, Churchill, 1860
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Paul Ehrlich (1854-1915) The First Clinical
Pathologist

• Ehrlich was another 19th century German physician
  who recognized that reproducible changes in the
  blood and urine could be correlated with
  morphologic organ changes in specific disease
  states
• That realization led to the development of
  diagnostic hematology and clinical chemistry

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Paul Ehrlich, M.D.
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The 20th Century Pathology Arrives as a Medical
Specialty

• Specialty certification is organized and granted
  by the American Board of Pathology, as of 1936

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Selected Non-neoplastic Diseases Described by
Pathologists in the 20th Century

• Graft versus host disease
• Lymphangioleiomyomatosis
• Multiloculated thymic cyst
• Inflammatory polyps of the GI tract
• Necrotizing sialometaplasia
• The currently-recognized glomerulonephritides
• Radial scar of the breast
• Microglandular mammary adenosis
• Pseudoneoplastic myositides and fasciitides
• Progressive multifocal leukoencephalopathy
• Kikuchis disease

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Graft-vs-host disease Lymphangioleio-
Dense deposit disease Esophagus
myomatosis C3
immunofluorescence
Progressive multifocal leuko-
Mammary radial scar encephalopathy ISH
for JC virus
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Advances Deriving from Observational Research in
Pathology in the 20th CenturyClassification of
Other Disease Entities

• -Essentially all specialized carcinoma, sarcoma,
  blastoma, germ cell tumor, and lymphoma
  morphotypes
• -Pseudoneoplastic quasi-neoplastic disorders
  (e.g., nodular fasciitis, myositis ossificans,
  Rosai-Dorfman disease, virus-associated
  hemophagocytosis)
• -Langerhans non-Langerhans histiocytoses
• -Separation of special melanocytic nevus variants
  from malignant melanoma
• -Recognition of the AIDS complex
• -Identification of several specific infectious
  diseases

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Pneumocystis-AIDS Cytomegalovirus-lung
Rosai-Dorfman Disease-S100
Pleuropulmonary Anaplastic large-
Spitz nevus Sarcomatoid Blastoma
cell lymphoma-
carcinoma ALK-1
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MODERN SUBSPECIALTIES IN PATHOLOGY

• Surgical pathology
• Autopsy forensic pathology
• Cytopathology
• Neuropathology
• Pediatric pathology
• Dermatopathology
• Hematopathology
• Clinical chemistry
• Microbiology infectious disease
• Transfusion medicine
• Diagnostic immunopathology
• Cytogenetics
• Molecular diagnostics

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Teaching in the Surgical Pathology Laboratory
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Techniques in Pathology

• Patient-Related
• Fine needle aspiration biopsy
• Apheresis
• Bone marrow aspiration biopsy
• Procedural
• Frozen section
• Autopsy
• Prosection of gross specimens
• Light, polarization, phase-contrast microscopy
• Electron microscopy
• Immunohistology
• In-situ hybridization comparative
  genomic hybridization
• Flow cytometry
• Cytogenetics
• Chromatography
• Polymerase chain reaction nucleic acid blotting
  technologies
• Mass spectroscopy
• Spectrophotometry
• Bacterial, mycological, viral cultures

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Fine Needle Aspiration Biopsy
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Fine Needle Aspiration Biopsy-- Invasive Breast
Carcinoma
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Therapeutic Apheresis
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Diagnostic Transmission Electron Microscope
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Flow Cytometry-- Peripheral T-cell Lymphoma
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Mass Spectrogram for Trace Metal Analysis of
Liver Tissue
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Biochemical Slant Tube Set for Microbial
Identification
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Southern Blot-- Rearrangement of IgH gene loci in
B-cell lymphoma
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Cytogenetics Spectral Fluorescent Karyotype
Showing Normal Chromosomal Pattern
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Objectification of Diagnoses in Anatomic
Pathology A Continuing Goal Major Focus of
Translational Research

• Morphology
• Flow Cytometry
• Electron microscopy
• Immunohistochemistry
• In-situ hybridization
• Nucleic acid blotting technologies

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Right Renal/Perirenal Mass in Adult Male-- Renal
Cell Carcinoma?
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Right Renal/Perirenal Mass in Adult Male-- Renal
Cell Carcinoma?
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Right Renal/Perirenal Mass in Adult
Male--Electron micrograph showing abundant smooth
endoplasmic reticulum (a feature of steroidogenic
cells)
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Right Renal/Perirenal Mass in Adult
Male--Positive Immunohistochemical Stain for
Inhibin Diagnosis Adrenocortical Carcinoma
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Enlarged left cervical lymph node in 49 year old
woman-- Reactive lymphadenitis or follicular
lymphoma?
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Enlarged left cervical lymph node in 49 year old
woman-- Positive CD10 immunostain in follicular
structures Diagnosis Follicular lymphoma
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Enlarged left cervical lymph node in 49 year old
woman-- Positive bcl-2 immunostain in follicular
structures Diagnosis Follicular lymphoma
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Tumefactive and ulcerative lesion of the lips in
a 29 year old man with HIV infection---
infectious or neoplastic?
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Tumefactive and ulcerative lesion of the lips in
a 29 year old man with HIV infection---
Microscopic image suggesting HSV infection
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Tumefactive and ulcerative lesion of the lips in
a 29 year old man with HIV infection-- Positive
HSV-1 immunostain
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Tumefactive and ulcerative lesion of the lips in
a 29 year old man with HIV infection--- Electron
micrograph showing HSV-1 virions
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Anatomic Pathology Activities in Which Medical
Students Can Participate

• Gross examination prosection of surgical
  pathology specimens
• Frozen section
• Autopsy
• Microscopy case signout

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Quote from Sir William Osler (Arguably the
Greatest Clinical Physician in History)

• To know Pathology is to know Medicine

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