English translation : granulation tissue
Inflammatory reaction and granulation tissue
A 40-year-old man, with no past medical history, hurts his finger with a screwdriver while fixing a shelf in his kitchen.
The screwdriver creates a cutaneous wound (an ulceration). This wound is equivalent to an "injury" of the tissue.
This physical stimulus will activate successive reactive phenomenon in the tissue. This succession of tissue reactions is known as the inflammatory reaction. Other types of injurious trigger can engender an inflammatory reaction : chemical, infectious, thermal ...
What are the tissular and/or molecular mechanisms underlying the occurence of each of these 4 clinical signs ?
The 4 signs of inflammation correspond to the first phase of the acute inflammatory reaction :
Question 2 :
In which order are recruited the different types of leukocytes from the circulating blood to the inflammatory infiltrate ?
We theoretically divide the continuation of the inflammatory reaction in 3 phases (after the vascular exudative phase) :
- the cellular phase : infiltration with diverse types of cells coming from
- the local connective tissue : fibroblasts, endothelial cells, resident histiocytes.
- exogenous particles : bacterias, foreign bodies
- endogenous particles : cellular debris (pus, necrosis), exudate
- the healing phase : reconstitution of the connective tissue that has been destroyed by the injurious stimulus and during acute inflammation
These 3 phases are not mutually exclusive in time and space. They can coexist in different areas of one lesion.
Let's come back to our patient. He did not take care of his wound, and continued to work. He did not protect the wound and exposed it to repeated trauma.
Clinically : During the first 48 hours, the wound filled with a red tissue protruding above the level of the surrounding skin. (see Image below).
There is an excessive amount of granulation tissue that blocks re-epithelialization. This has been called exuberant granulation (or proud flesh). It is favored by repeated trauma, especially on the fingers.
Let's see the slide of an example of exuberant granulation : virtual slide 1
(On this slide, epidermis is downwards and deep dermis upwards)
- The lateral epidermis is thinned
- there is a central ulceration : the epidermis is replaced by a fibrino-leukocytic exudate.
- Under the ulceration, there is extensive granulation tissue. Capillaries are numerous, lying in a loose edematous connective tissue, infiltrated by neutrophils, lymphocytes and histiocytes.
- deeper, one can see fibrosis with rare inflammatory cells.
Question 3 :
Virtual slide 1 has 6 annotated areas. What do they contain ? (one or more answers)
Area A : Area B :
a- dilated capillaries a- lymphocytes
b- fibrin deposits b- neutrophils
c- neutrophils c- histiocytes
d- normal epidermis d- giant cells
Area C : Area D :
a- dilated capillaries a- necrosis
b- edematous connective tissue b- fibrin deposits
c- dense fibrosis c- protein-rich exudate
d- necrosis d- red blood cells
Area E : Zone F :
a- hyperplastic epidermis a- inflammatory infiltrate
b- ulcerated epidermis b- fibrosis
c- dermis c- capillaries
d- thinned epidermis d- fat tissue