TIPS FOR LABORATORY PRACTICAL EXAM

Winter 2013

LABORATORY PRACTICAL EXAM

GENERAL PATHOLOGY - VPM 152

Friday April 19, 2013

YOU NEED TO BRING: Clip Board (To Write On), Pen / Pencil

WHAT TO WEAR: Lab Coat

Gloves (optional - since specimens can only be touched under supervision)

REMINDERS: Read the history carefully and answer the questions that are asked!

There will be 25 stations with 80 minutes to complete the exam - so organize your

time accordingly (~ 3 minutes per station)

With 30 students and 25 stations there will be times when there are 2 people at one

station (but no more than 2 people at any one station at a time)

Do not touch the specimens without supervision - if you need to manipulate a

specimen to see a different angle or texture, please put your hand up so an instructor

can assist you.

Be warned that any observation of cheating will result in a grade of zero for this exam - -

- - do not let your eyes wander

SCHEDULE: Group A 9:30 to 10:50 - Acheson to Glaude

Group B 11:00 to 12:20 - Gordon to Woodside

IS IT INFLAMMATION

OR OTHER?

If Inflammation

Mostly you decide

its inflammation

when you see

exudate.

What does the

exudate tell you

about etiology?

Fibrinous • esp Bacteria - ACUTE

Suppurative

• esp Bacteria

Granulomatous

• specific bacteria, many fungi

Hemorrhagic

• Toxin (bacterial or otherwise)

• Ischemia

Eosinophilic

• esp parasites & allergies

FIBRINONECROTIC EXUDATE

• typically occurs when there is necrosis

of well-vascularized epithelial surface

= necrosis + fibrin exudation

• examples - above is an acute

fibrinonecrotic tracheitis due to viral

infection and to the right an acute

fibrinonecrotic enteritis due to bacterial

infection

Organ Exudate (type of inflammation)

Distribution Duration Extent

Nephritis Suppurative Focal Peracute Minimal

Fibrinous Multifocal Acute Mild

Pneumonia Necrotizing Locally extensive

(segmental) Subacute Moderate

Enteritis Granulomatous Diffuse Chronic Marked

Hepatitis Catarrhal Chronic-active (severe)

Etc. Etc. Etc.

Use the following formula for a morphologic diagnosis of an inflammatory response

& you already have 2 parts (organ-itis + exudate)

Distribution

FIBRIN NEUTROPHILS

(pus) ACUTE

FIBROSIS NEUTROPHILS

and/or FIBRIN

CHRONIC-ACTIVE

GRANULOMATOUS INFLAMMATION

FIBROSIS CHRONIC

OR

OR

&

&

Duration

Above - Acute fibrinous pericarditis

Right – Chronic (chronic-active) fibrinous pericarditis

Above - Acute fibrinous or fibrinopurulent arthritis

Right – Chronic (chronic-active) fibrinous arthritis

Abscesses are a type of

suppurative inflammation that is

chronic (chronic-active); ie pus

surrounded by a fibrous capsule!

M.Dx = Hepatitis, suppurative,

multifocal, chronic (chronic-active),

severe = Hepatic abscess

Caseous exudate in most

mammals means

granulomatous

(& implies mycobacteria,

fungal, foreign body, etc).

Be aware of caseous

lymphadenitis in sheep, in

which the caseous

exudate is dried

(inspisated) pus (ie

suppurative, not

granulomatous exudate)

& birds which don’t have

neutrophils, caseous

exudate can represent

heterophilic or

granulomatous

inflammation

Extent / Severity

Mild

Moderate

Marked (severe)

How much tissue damage?

How much exudate?

If its not inflammation – is it:

Necrosis / degeneration

Pigmentary change

Circulatory disturbance

Adaptation / Growth disturbance

Neoplasia

Necrosis / degeneration

M.Dx. = Myocardial necrosis & mineralization,

locally-extensive, marked

Name of Dz = Nutritional myopathy

or White muscle disease

Etiology = deficiency of Vit E &/or Sel

Pathogenesis = free radical damage due to

reduced antioxidant protection

Gross - enlarged yellow liver with rounded

edges, that is greasy when cut and floats

when placed in water.

Histo - hepatocytes are swollen with clear

well delineated vacuoles (which would stain

positive with oil red O = lipid) which often

displace the nucleus to the periphery

M.Dx. = Hepatic lipidosis, diffuse, marked

Necrosis / degeneration

Gross - enlarged yellow liver with rounded

edges, that is not greasy when cut & does not

float when placed in water

Histo - hepatocytes are swollen with clear poorly

delineated vacuoles (which would stain positive

with PAS = glycogen) and nucleus not displaced

to periphery.

M.Dx. = Glycogen hepatopathy, diffuse, marked

H&E PAS

Necrosis / degeneration

Necrosis / degeneration

Pigmentary change or tissue deposits

Pigmentary change or tissue deposits

Circulatory disturbance – eg edema, congestion, hemorrhage,

infarct, thrombosis, embolism, etc

Circulatory disturbance – eg edema, congestion, hemorrhage,

infarct, thrombosis, embolism, etc

Circulatory disturbance – eg edema, congestion, hemorrhage,

infarct, thrombosis, embolism, etc

note thrombus or thromboemolus

in pulmonary artery (above) and

at bifurcation of distal abdominal

aorta (right)

Adaptation

Atrophy vs hypertrophy

normal

normal

Growth disturbance - hypoplasia / aplasia, hyperplasia, etc

Atrophy vs Hypoplasia?

normal

Epidermal hyperplasia

Nodular hyperplasia – common change in older animals

Growth disturbance - hypoplasia / aplasia, hyperplasia, etc

Neoplasia Benign Neoplasia – note well delineated and well differentiated

Neoplasia

Malignant Neoplasia

- note local invasion

Neoplasia

Malignant Neoplasia

- note local invasion & metastasis

Malignant Neoplasia

- local invasion with blocked lymphatics (note pitting edema bottom left), tumor

embolus in vessel (top right) and metastasis to lymph node (bottom right).