Intro to Pathology and Morphological Diagnoses

Health

the normal condition of the body, in which all cells, tissues, organs, and systems are structurally intact and functioning properly

Disease

any detectable deviation from the normal range

Three forms of evidence for disease:

1.) symptoms

2.) signs

3.) lesions

Four main aspects of disease:

1.) etiology

2.) pathogenesis

3.) morphologic changes

4.) functional consequences

etiology

anything that can disrupt the normal functioning of a cell, tissue, organ, or system; what is "causing" the disease

etiology is aka...

the cause of the disease

Two types of etiology:

1.) intrinsic

2.) extrinsic

intrinsic etiology

cause of disease from inside the body; uncontrollable individual-specific factors predisposing the host to disease

Three types of intrinsic etiology

1.) primary

2.) secondary

3.) idiosyncratic

primary intrinsic etiology

genetic mutations in germ or somatic cells that arise spontaneously either during embryogenesis (congenital) or after birth (acquired)

examples of a primary intrinsic etiology

-hip dysplasia in german shepherds

-brain tumors in boxers

secondary intrinsic etiology

Physiologic abnormalities related to age, sex, species; modify the expression of a disease

examples of secondary intrinsic etiology

-age --> younger animals more affected by infectious disease, older animals more affected by neoplasia

-color --> deafness in white cats

-sex --> mammary cancer in female dogs, urinary obstruction in male cats

-species specific --> swine get hog cholera, horses get laminitis

idiosyncratic intrinsic etiology

a patient-specific disease; often related to enzymopathy (inherited or acquired)

idiosyncratic intrinsic etiologies may be triggered by ________ factors

extrinsic

extrinsic etiology

cause of disease from outside the body

Two types of extrinsic etiology

1.) animate agents

2.) inanimate causes

extrinsic etiology: animate agents

aka pathogens and their products (fungi, bacteria, parasites, viruses, etc)

extrinsic etiology: inanimate causes

energy (radiation, thermal), physical forces (pressure, trauma), surgical intervention, xenobiotics (chemicals, drugs, toxins)

Pathogenesis

the sequence of events from the start to the end of a disease

Pathogenesis encompases both ______ and _______ to a disease

mechanisms and responses

Lesions

a visible manifestation of disease; the structural or morphologic effects of a disease

Three levels that lesions are visualized:

1.) gross pathology

2.) histopathology

3.) ultrastructural

gross pathology

macroscopic; seen with the naked eye

histopathology

microscopic; seen using a light microscope

ultrastructural

cell organelles; seen with an electron microscope

Lesions are identifiable as a departure from ________

normal

Lesions usually fall into three general categories:

1.) something has been added

2.) something has been taken away

3.) something has been altered

Lesions where something has been added

The tissue contains something not normally present (cells, fluid, pigment, microbial agents, foreign bodies, etc)

Lesions where something has been taken away

The tissue looks different with normal elements gone (atrophy, hypoplasia, degeneration, necrosis)

Lesions where something has been altered

The normal tissue components are present but not normal (malformations, dysplasia, metaplasia, neoplasia)

metaplasia

when one tissue type turns into another tissue type

Examples of attributes of lesions:

-color

-consistency

-contours

-distribution

-duration

-extent

-location

-margins

-shape

-size

-texture

Pathognomonic lesions

A lesion so distinctive and unique that it can only be caused by a single etiologic agent or disease process

Pathognomonic lesions have very high _______

specificity (if present, it confirms a disease)

*ex: diamond shaped rash confirms swine erysipelas

Necropsy

post mortem dissection of an

animal to determine the cause of death

Autopsy

the post mortem dissection of a human being to define the cause of death

Biopsy

the surgical removal of a representative sample of tissue from a suspicious lesion for a diagnosis

Prognosis

prediction of a future outcome for the patient (excellent, fair, guarded, poor)

Diagnosis

determination of the nature or cause of a disease

Three types of diagnosis:

1.) morphologic diagnosis

2.) etiologic diagnosis

3.) disease diagnosis

morphologic diagnosis

An orderly, detailed description of a lesion; a summary of the lesion, but generally does not describe what is causing the lesion

Five components for a morphologic diagnosis:

1.) affected structure (cell, tissue, organ)

2.) distribution

3.) nature of lesion (process)

4.) severity

5.) duration

Four ways to describe distribution:

1.) focal

2.) multifocal

3.) locally extensive

4.) diffuse

focal

Limited to one site

focally to locally extensive

All of the tissue in a zone is affected

multifocal

multiple sites

multifocal to coalescing

Many lesions present that appear to be growing together or fusing

diffuse

involves the entire tissue/organ; no normal tissue is left

Two types of the nature of a lesion (process)

1.) non-inflammatory

2.) inflammatory

non-inflammatory process

does not involve the body's immune-mediated inflammatory response

Six examples of a non-inflammatory process:

1.) degeneration

2.) pigmentation

3.) mineralization

4.) disturbances of growth

5.) neoplasms

6.) displacement of viscera

degeneration

the deterioration of tissues

pigmentation

deposited pigment or color in a tissue

mineralization

calcium depositions in the tissue

disturbances of growth

atrophy, hypertrophy, hyperplasia, etc

neoplasms

abnormal growths of new tissue that are classified as benign or malignant

How are neoplasms named?

Organ + name of neoplasm

Ex: Kidney: Lymphosarcoma -or- Renal lymphosarcoma

displacement of viscera

volvulus, torsion

inflammatory process

does involve the body's immune-mediated inflammatory response

What suffix is added to the end of an organ when inflammation is involved?

"itis"

Five descriptors for severity of a lesion:

1.) minimal

2.) slight/mild

3.) moderate

4.) marked/moderately severe

5.) severe

Four descriptors for duration of a lesion:

1.) acute

2.) subacute

3.) chronic

4.) chronic-active

acute

hours to a day or so

subacute

one or a few days

chronic

several days to weeks, months, or years

chronic-active

chronic duration but ongoing inciting stimulus

Example of a morphologic diagnosis

Acute, severe, diffuse, suppurative encephalitis

What descriptor must be used for a lesions on paired organs?

unilateral or bilateral

Three paired organs:

1.) Adrenal glands

2.) Kidneys

3.) Repro organs (testis, ovaries, etc)

etiologic diagnosis

A diagnosis that names the cause or agent of the disease; comprised of two words- the causative agent (etiology) and the site (organ or tissue) (i.e., mycobacterial enteritis)

Three descriptors of an etiologic diagnosis

1.) agent or cause

2.) location

3.) process

Examples of an etiologic diagnosis

-Microsporidial encephalitis

-Parvoviral enteritis

disease diagnosis

A diagnosis that states the "name of the disease" (ex Johne's disease)

The term for the distinctive target lesions pictured that are characteristic of Histomonas meleagridis in a bird is:

A Pathogenesis

B Prognostic

C Predictived

D Pathognomonic

Pathognomonic

What is the distribution of this lesion?

A Focal

B Locally extensive

C Multifocal to coalescing

D Diffuse

Multifocal to coalescing

Which of the Following is an Etiologic

Diagnosis?

A Intestine: Severe, diffuse, granulomatous enteritis

B Intestinal histoplasmosis

B Intestinal histoplasmosis

*A is a morphological diagnosisf

Which of the Following is the Morphologic Diagnosis?

A Clostridial enteritis

B Small intestine: Enteritis, necrohemorrhagic, acute, diffuse,

marked, with vasculitis, edema, and numerous bacilli

C Clostridium perfringens type C

B Small intestine: Enteritis, necrohemorrhagic, acute, diffuse,

marked, with vasculitis, edema, and numerous bacilli

*A is etiologic, C is the etiology

Case 1: What organs are present?

What two organs are present here?

a Liver and Gallbladder

b Stomach and Intestine

c Heart and Lung

d Spleen and Lymph node

c Heart and Lung

Case 1: Has anything been added or removed?

a added

b removed

a added

Case 2: What is the Lesion Distribution?

a Focal

b Locally Extensive

c Multifocal/Coalescing

d Diffuse

b Locally Extensive

Case 2: Has something been Added or Removed?

a Added

b Removed

a Added

Case 3: What is the lesion distribution?

a Focal

b Multifocal/Coalescing

c Locally Extensive

d Diffuse

b Multifocal/Coalescing

Case 3: What do you think the Duration is for this Lesion?

a Acute

b Subacute

c Chronic

a Acute

*Lesions are bright to dark red (hemorrhage), a chronic hemorrhage would be green/blue/brown as blood is broken down (almost like a bruise), no fibrosis present

Case 4:

Case 5:

Case 5:

Case 6:

Case 6:

Case 6:

What type of Diagnosis is the following? Patient presents with chronic, severe, multifocal granulomatous pneumonia.

A Etiologic diagnosis

B Disease diagnosis

C Condition

D Morphologic diagnosis

D Morphologic diagnosis

Which of the following is an etiologic diagnosis?

A Pulmonary lymphoma

B Johne's disease

C Diffuse granulomatous pneumonia

D Mycotic rumenitis

D Mycotic rumenitis