CHAPTER 2 Flashcards
Gross Indicators/Characteristics of Necrosis
The gross indications of necrosis are:
- loss of color or paleness of the tissue
- loss of strength of the tissue as it softens
- a definite zone of demarcation between necrotic and viable tissue
- the location or pattern of the lesion
refers to death of cells following irreversible cell injury. It is the outcome of irreversible
cellular degeneration.
Necrosis
2 Microscopic indicators:
- Cytoplasmic Changes
2.Nuclear Changes
Cytoplasmic Changes:
a)Adicophilia of the cytoplasm (refers to
severely eosinophilic or reddish cytoplasm)
b)Lysis of the cytoplasm – owing to lysosomal
disruption
Nuclear Changes:
1.Pyknosis
2.Karyorrhexis
3.Karyolysis
4.Absence of the nucleus .
–
condensed nucleus
Pyknosis
–shattered nucleus
Karyorrhexis
–
dissolving nucleus
Karyolysis
-
after dissolution
leaving a hollow, ghost appearance.
Absence of the nucleus
necrosis refers to an area of
necrosis in which the gross and microscopic
architecture of the tissue and some of the cells are
recognizable.
This condition may result from acute
deprivation of blood supply.
Coagulation
necrosis is another
morphological type of necrosis and suggests
a semi-solid or fluid mass that has been
present for some time undergoing selfdigestion.
- implies the rapid enzymatic lysis of dead
cells.
Coagulative necrosis may progress to liquefactive necrosis. This type of necrosis is seen particularly in
the central nervous system, and in abscesses.
Liquefactive or liquefaction
Necrosis
- Liquefactive necrosis
- is manifested by loss of
recognizable architecture and will
contain combinations of much dark amorphous
nuclear debris and eosinophilic cytoplasmic debris, perhaps mixed with components of blood clots, hemorrhage , thrombi and calcification. - implies “curdle or cheesy” as in tuberculous lesions.
- characterized by the presence of
friable, cheesy, amorphous material in
necrotic area. This term is usually
reserved for tuberculous lesions.
Caseous or Caseation Necrosis
is distinctive
type of necrosis and occurs in the
abdominal cavity or under the skin.
On cut surface, there are had white
gritty lumps.
- seen in pancreatitis
- and in adult cow, can
cause death due to
necrosis and hardening of
intestines (lipomatosis).
Fat necrosis
occurs when saprophytic
bacteria grow in necrotic tissue.
The requirement for _____________ is
NECROSIS PLUS PUTREFACTION
Gangrene or Gangrenous Necrosis
- Gangrene
–
this occurs in necrotized
portion of the skin with moisture loss due
to evaporation and drainage and presence
of saprophytic bacteria. Ischemia is the
common cause ( e.g.
resultant of tight
bandages and casts). Line of demarcation
that usually progresses up the affected
area between the viable and dark or black
gangrenous tissue is seen. Extremities
such as the tail, ears or limbs are the usual
location.
Dry gangrene
– or moist gangrene. Color is usually black, with gas bubbles and may have much
hemorrhage and edema in and around the lesion.
Wet gangrene
– a form of coagulative necrosis
resulting from a sudden deprivation of blood
supply. Commonly occurring in areas or
organs with end artery (i.e., kidney) blocked
by thromboembolic lesions.
Infarct
– a type of coagulative necrosis
in striated muscles characterized by loss of striations following necrosis
Zenker’s Necrosis (Zenker’s degeneration)
– a special form
of necrosis with fibrinoid
accumulating in along walls of
blood vessel and connective
tissues.
Fibrinoid Necrosis
OTHER TERMS USED IN ASSOCIATION WITH NECROSIS
Erosion
Ulcer
Slough
– is a shallow area of necrosis confined to epidermis that heals without scarring.
Erosion
– is an excavation of a surface produced by necrosis and sloughing of the necrotic debris
and implies involvement of the tissue below the surface layer.
Ulcer
is a piece of necrotic tissue in the process of separation from viable tissue and implies a
process of shedding when used with reference to a surface.
- a piece of necrotic tissue separating from viable tissue.
Slough
Slough – is a piece of necrotic tissue in the process of separation from viable tissue and implies a
process of shedding when used with reference to a surface.
- a piece of necrotic tissue separating from viable tissue.
- This term is applied to necrosis of surface epithelia. Other terms used in
reference to necrosis: ???
- Malacia – an area of liquefactive necrosis of the nervous tissues. Literally means “softening”.
- Sequestrum – an isolated necrotic mass.
- process is called sequestration.
