Lab 8: Chronic Inflammation and Repair

Question 1

Canine, lung. This animal has had a cough for several weeks, dyspnea, and exercise intolerance.

1. What is this pointing at (hard to tell)
2. ?
3. ?
4. ?
5. ?

Answer 1

1. multiple confluent granulomas disseminated throughout the parenchyma
2. lymphocytes at the periphery of the granulomas or pyogranulomas (if neutrophils are abundant.).
3. few neutrophils
4. Macrophages
5. yeast bodies of Blastomyces dermatitidis (cytology image)

Question 2

Canine, lung. This animal has had a cough for several weeks, dyspnea, and exercise intolerance.

• Describe what is happening here

Answer 2

• In this section of lung there are multiple confluent granulomas disseminated throughout the parenchyma.
• Centrally these granulomas are composed of spheroidal sheets of epithelioid macrophages and variable numbers of neutrophils.
• Surrounding clusters of macrophages is a dense inflammatory infiltrate composed of macrophages, neutrophils, fibroblasts, and aggregates of lymphocytes.
• The remaining parenchyma is relatively normal except for postmortem collapse and increased neutrophils in capillaries.
• In the centers of some granulomas you may find spherical yeast cells (10‑20 μm diameter).
• These have a lightly basophilic nucleus surrounded by a thick refractive cell wall.
• These organisms are Blastomyces dermatitidis and the disease they cause is blastomycosis.

Question 3

Canine, lung. This animal has had a cough for several weeks, dyspnea, and exercise intolerance.

• Why do these fungal agents cause a granulomatous reaction?

Answer 3

• Fungi have complex cell walls that are not easily killed by killing mechanisms of neutrophils.
• They tend to persist and require macrophages to kill them.
• Even then, it is difficult and longtime inflammation can occur.

Question 4

Canine, lung. This animal has had a cough for several weeks, dyspnea, and exercise intolerance.

• Histomorphologic Diagnosis?

Answer 4

Severe chronic widely disseminated (or multifocal) (pyo)granulomatous pneumonia (with fungal yeast bodies)

Question 5

Equine. This tissue grew at the site of a wire cut that was not sutured. The section you have is from the middle part of wound.

1. generally what is happening on this side of the image?
2. this side?
3. here? (this is to the right of the above image)

Answer 5

1. Granulation tissue: Surface is to the right, which is the part that is proliferating.
2. To the left are the more mature, older parts of the process where collagen is much denser.
3. Surface is to the right, where the tissue is very loose and has large numbers of neutrophils on the surface (which is exposed to bacteria and hence chemotactically draws pmns (neutrophils).)

Question 6

Equine. This tissue grew at the site of a wire cut that was not sutured. The section you have is from the middle part of wound.

1. What is seen here?
2. ?
3. ?

Answer 6

Granulation tissue:

1. note new blood vessels or capillary buds and
2. loosely arranged fibroblasts.
3. Pmns

Question 7

Equine. This tissue grew at the site of a wire cut that was not sutured. The section you have is from the middle part of wound.

1. what is seen here?
2. ?

Answer 7

Moderately early granulation tissue: Surface is to the right.

1. Note new blood vessels or capillary buds and
2. loosely arranged fibroblasts.

Question 8

Equine. This tissue grew at the site of a wire cut that was not sutured. The section you have is from the middle part of wound.

1. What is this?
2. ?
3. ?
4. Why is this different than the previous granulation tissue images?

Answer 8

Surface is to the right.

1. Note blood vessels
2. fibroblasts
3. abundant mature collagen.
4. It is mature granulation tissue
   
   • This more closely resembles scar tissue.

Question 9

Equine. This tissue grew at the site of a wire cut that was not sutured. The section you have is from the middle part of wound.

• What is the function of granulation tissue?

Answer 9

• Granulation tissue is repair tissue.
• It serves to fill in defects left by wounds and can also initiate a wall around an irritant that cannot be otherwise eliminated.
• Eventually it will mature into fibrous connective tissue producing scarring.

Question 10

Equine. This tissue grew at the site of a wire cut that was not sutured. The section you have is from the middle part of wound.

• What is granulation tissue characterized by?

Answer 10

• Granulation tissue is characterized by fibroblasts, endothelial buds (angiogenesis), and production of an extracellular matrix.
• Granulation tissue also often contains macrophages. (or neutrophils-if an open wound)

Question 11

Equine. This tissue grew at the site of a wire cut that was not sutured. The section you have is from the middle part of wound.

1. Histopathologic Diagnosis
2. What can this also be called in horses?

Answer 11

1. Granulation tissue with acute inflammation at the surface.
2. Granulation tissue in horses is sometime termed “proud flesh”, actually excessive attempts at repair that is common in horses

Question 12

8 year old Labrador Retriever euthanized for progressive cardiac disease.

1. Describe the lesion:
2. What is the likely etiology of these lesions?

Answer 12

1. The kidney surface contains multifocally coalescing cortical indentations ranging from .5cm to 2cm in diameter.
2. etiology- Infarction.

Question 13

8 year old Labrador Retriever euthanized for progressive cardiac disease.

1. How did the original injury resolve?
2. Name the lesion.

Answer 13

1. Fibrosis
2. Chronic renal infarcts.

Question 14

Signalment and history: Tissue from an 8 year old Holstein cow. Upon presentation, she had ventral pitting edema in her brisket and under her jaw. Pulsating jugular veins were observed. Approximately 1 liter of purulent fluid was removed from the pericardial sac.

• Describe the lesion.

Answer 14

• The epicardium is diffusely covered by a 0.5-3cm thick layer of tightly adhered, pale tan material with a smooth and glistening appearance.
• There is also a small piece of thickened pericardium at the base of the heart which is adhered to the surface of the epicardium by the fibrous connective tissue.

Question 15

Signalment and history: Tissue from an 8 year old Holstein cow. Upon presentation, she had ventral pitting edema in her brisket and under her jaw. Pulsating jugular veins were observed. Approximately 1 liter of purulent fluid was removed from the pericardial sac.

• Give a morphologic diagnosis for the lesion.

Answer 15

Heart: Severe chronic diffuse fibrosing epicarditis and pericarditis

Question 16

Signalment and history: Tissue from an 8 year old Holstein cow. Upon presentation, she had ventral pitting edema in her brisket and under her jaw. Pulsating jugular veins were observed. Approximately 1 liter of purulent fluid was removed from the pericardial sac.

1. What is the significance of the clinical finding of purulent fluid in conjunction with the gross lesions you described?
2. How are the gross lesions connected to the ventral pitting edema?

Answer 16

1. The presence of purulent fluid indicates that neutrophils are still being actively recruited to the site, which means the inciting cause is likely ongoing.
   
   • This is common in the case of “hardware disease” or traumatic reticulopericarditis.
2. Ventral pitting edema is likely due to progressive right heart failure.
   
   • Because the right ventricular muscle mass is smaller, the pressure from the pericardial fluid affects the right side of the heart before the left.
   • Decreased output causes expansion of the venous capacitance vessels- increased hydrostatic pressure.

Question 17

Signalment and history: Tissue from a 9 year old, Thoroughbred mare that presented with left hind foot lameness. This is the right hind foot. Affected area is the site of a previous fracture of the right hind calcaneal bone that was healing. (Note: there was also a laceration of the gastrocnemius tendon)

1. ?
2. ?

Answer 17

1. Radiating scar tissue
2. Chestnut
   
   • Definition from wikipedia-
   • The chestnut, also known as a night eye,[1] is a callousity on the body of a horse or other equine, found on the inner side of the leg above the knee on the foreleg and, if present, below the hock on the hind leg. It is believed to be a vestigial toe

Question 18

Signalment and history: Tissue from a 9 year old, Thoroughbred mare that presented with left hind foot lameness. This is the right hind foot. Affected area is the site of a previous fracture of the right hind calcaneal bone that was healing. (Note: there was also a laceration of the gastrocnemius tendon)

• Describe the lesion.

Answer 18

1. Protruding from the surface of the skin is a 6 x 4 cm x 2 cm oval lesion that is raised from the surface of the surrounding tissue and bulges over the adjacent haired skin.
   
   • This raised lesion is firm, gray to tan with a granular surface that is multifocally ulcerated and covered by a thin layer of yellow-brown to red material.
   • The transitional area from the lesion to normal haired skin is alopecic, white, and firm.
   • This rim of fibrous tissue is .5-1 cm wide and has occasional streaks of similar tissue that radiate into the haired skin.
2. Dorsal to this mass is a roughly circular 1 cm x 1 cm ulcer with a tan to red surface.
   
   • This is surrounded by an irregular 2 cm by 4 cm roughly oval rim of alopecic skin that is firm and pale.

Question 19

Signalment and history: Tissue from a 9 year old, Thoroughbred mare that presented with left hind foot lameness. This is the right hind foot. Affected area is the site of a previous fracture of the right hind calcaneal bone that was healing. (Note: there was also a laceration of the gastrocnemius tendon)

• Give a morphologic diagnosis for the lesion.

Answer 19

Right rear leg, skin: severe, chronic, focal ulcerative dermatitis with granulation tissue (Or Mdx: focal dermal granulation tissue with ulceration)

Question 20

Signalment and history: 8 year old Holstein that was off feed

• Describe the lesions

Answer 20

• The pulmonary pleura is diffusely thickened and firm.
• The interlobular septa are expanded by firm, light tan connective tissue (fibrosis).
• The pulmonary parenchyma is mottled tan and diffusely consolidated (firm)

Question 21

Signalment and history: 8 year old Holstein that was off feed

• Give a morphologic diagnosis for the lesion.

Answer 21

Chronic, diffuse, fibrous pleuritis and chronic diffuse bronchopneumonia.

Question 22

Signalment and history: Tissues from an 18 year old DSH with progressive weakness, declining neurologic status and deteriorating renal function.

• Describe the above organ lesions

Answer 22

Widely disseminated throughout the lungs, there are raised, soft, irregular, tan-yellow nodules approximately 0.5 – 2.0 cm in diameter which extend into the lung parenchyma on cut surface.

Question 23

Signalment and history: Tissues from an 18 year old DSH with progressive weakness, declining neurologic status and deteriorating renal function.

• describe the bellow organ lesions

Answer 23

• The kidney contains multifocal to coalescing white/tan nodules, ranging from 1 to 5mm in diameter, with confluences up to 3cm.
• Nodules efface renal cortical parenchyma, multifocally extending into the medulla.

Question 24

Signalment and history: Tissues from an 18 year old DSH with progressive weakness, declining neurologic status and deteriorating renal function.

• List 4 differential diagnoses for pulmonary nodules

Answer 24

(remember NAGH).

• N = neoplasia
• A = abscess
• G = granuloma
• H = hypertrophy (not a common differential for lungs or kidneys)

Question 25

Signalment and history: Tissues from an 18 year old DSH with progressive weakness, declining neurologic status and deteriorating renal function.

• Microscopic examination revealed the pulmonary and renal nodules to be composed of moderate numbers of macrophages admixed with myriad 5-7um yeast-like structures with thick clear capsules, conferring a ‘soap bubble-like’ appearance to the organisms.
• Identify the organism. (even though she mentioned we would not have to know organisms but she asks this in the lab key)

Answer 25

These organisms are consistent with Cryptococcus spp.

Question 26

Signalment and history: Tissues from an 18 year old DSH with progressive weakness, declining neurologic status and deteriorating renal function.

Microscopic examination revealed the pulmonary and renal nodules to be composed of moderate numbers of macrophages admixed with myriad 5-7um yeast-like structures with thick clear capsules, conferring a ‘soap bubble-like’ appearance to the organisms. These organisms are consistent with Cryptococcus spp.

• Based on the gross and histological findings, give an appropriate morphologic diagnosis for the pulmonary lesions.

Answer 26

Chronic widely disseminated granulomatous pneumonia with intralesional yeast bodies.

Question 27

Signalment and history: 6 month old female Percheron with a history of chronic diarrhea, 1 week duration, and ventral pitting edema. Photo at right: appearance of tissues at necropsy.

• Describe the lesion

Answer 27

Pale, proliferative, cerebriform patterned lesions were found diffusely within a thickened ileum and jejunum.

Question 28

Signalment and history: 6 month old female Percheron with a history of chronic diarrhea, 1 week duration, and ventral pitting edema. Photo at right: appearance of tissues at necropsy.

• Give a morphological diagnosis.

Answer 28

• Small intestine: Severe, chronic, multifocal proliferative enteritis
• FYI=
  
  • Histologically, the mucosa of the small intestine contains hyperplastic projections of intestinal villi, with intermittent areas of ulceration.
  • Warthin-Starry staining reveals large numbers of intracellular bacteria within the enterocytes.
  • These organisms are Lawsonia intracellularis.
  • The bacterium induces proliferation of enterocytes, and frequently causes disease in swine, as well as a variety of other species.