9/14- Cases 2: Pulmonary Infections

Question 1

What is seen here?

Answer 1

• Pneumonia
• Meniscus sign
• Likely pleural effusion

Question 2

What is seen here?

Answer 2

Inflamed lung in infectious pneumonia

• Inflammatory cells, blood, and fibrin in alveolar spaces (leaky capillaries)

Question 3

What is seen here?

Answer 3

• More inflammatory cells
• Fibrin (stringy material in background)

Question 4

What is seen here?

Answer 4

Congestion and edema phase of pneumonia

• Can see congested capillaries
• Leaky, so fluid gets out into alveolar spaces (pulmonary edema)

Question 5

What is seen here?

Answer 5

Red hepatization stage

• Lung has become very firm (like liver tissue)
• All alveolar spaces are filled with blood and edema fluid

Question 6

What is seen here?

Answer 6

Predominant cell in alveolar spaces = RBCs

Question 7

What is seen here?

Answer 7

Gray hepatization stage

• Over time, RBCs disintegrate and predominant cell becomes neutrophil
• Involved area has grey color; blood gone and replaced with neutrophilic exudate

Question 8

What is seen here?

Answer 8

Abscess- localized are of necrotic tissue (surrounded by wall)

Question 9

What is seen here?

Answer 9

Abscess (common complication of pneumonia)

• Necrotic center
• Wall of abscess = organizing fibrous tissue

Question 10

What is seen here?

Answer 10

Extra-pulmonary abscess (osteomyelitis)

• Due to dissemination of infection through blood
• Complication of pneumonia

Question 11

What is seen here?

Answer 11

Very necrotic lung tissue

Question 12

What is seen here?

Answer 12

CMV infection (cytomegalovirus pneumonitis)

• “Owl-eyed” inclusions with marginated chromatin

Question 13

What is seen here?

Answer 13

CMV infection has cytoplasmic as well as nuclear inclusions!

Question 14

What cells does CMV typically attack?

Answer 14

• Alveolar macrophages
• Endothelial cells
• Fibroblasts

Question 15

What organ is the most common site of opportunistic infections?

Answer 15

Lungs

Question 16

What pts are considered immunosuppressed?

Answer 16

• AIDS
• Chemotherapy (neutropenia, lymphopenia)
• Cancer itself Immunosuppression (anti-TNF, steroids…)
• Autoimmune disease
• Transplant
• Congenital immune deficiencies (or acquired)

Pts who are severely immunocompromised and infected with virulent organism may get lobar pneumonia from the onset (rather than progression from bronchopneumonia)

Question 17

What is seen here?

Answer 17

Gross example of bronchopneumonia

• Grossly patchy consolidation around airway

Question 18

What is seen here?

Answer 18

Bronchopneumonia

• Inflammatory exudate within bronchiole
• Few detached bronchial epithelial cells
• Wall of membranous bronchiole

Question 19

What is seen here?

Answer 19

Aspergillosis

• Nodule is a thrombus; angioinvasive organism
• Targetoid lesion: central reddish area (area of hemorrhagic infarction)

Question 20

What is seen here?

Answer 20

Wall of blood vessel with aspergillosis

• Hyphae stained black
• Septated dichotomous, Y-shaped branching

Question 21

What is seen here?

Answer 21

Crytptococcus

• Thin-necked buds
• Capsule represented as clear halos around budding yeast forms
• Commonly seen in immunocompromised pts

Question 22

What is seen here?

Answer 22

Pneumocystis infection

• Very frothy/foamy exudate within alveolar spaces
• Lung architecture mostly preserved

Question 23

What is seen here?

Answer 23

Pneumocystis infection

• Characteristic squashed ping-pong/football-shaped appearance

Question 24

What is seen here?

Answer 24

TB

• Can see multiple cavities (at least 2)
• Located in upper lung fields

Question 25

What are some epidemiological risk factors for TB?

Answer 25

• Substance abuse
• Low socioeconomic background

Question 26

What is seen here?

Answer 26

TB infection

• Acid fast positive organisms (fuschin stain)