CHAPTER 1
An Illustrated Glossary of Histological and Pathological Terms
9
Caseous Necrosis.
H&E,
3
97
Caseous necrosis
is a form of necrosis characterized by obliteration of the under-
lying tissue architecture and the formation of amorphous granular necrotic debris,
which grossly appears “cheesy,” hence the name
caseous
. Caseous necrosis is
highly characteristic of infection with
M. tuberculosis
and certain fungi and is a
type of granulomatous infl ammation.
Image:
This image shows a lymph node biopsy with granulomatous infl ammation and
necrosis (
to the right of the dashed line
) in a patient with
H. capsulatum
infection.
Coagulative Necrosis.
H&E,
3
97
Coagulative necrosis
is a form of necrosis characterized by preservation of cellular
outlines. Examples include necrosis of cardiac myocytes in myocardial infarction
and renal
necrosis.
Image:
This image shows global coagulative necrosis in a transplanted kidney due
to compromised perfusion after the transplant. Note the preserved architecture
with the glomerulus in the center surrounded by renal tubules. Note also the pale
eosinophilic staining with lack of nuclear staining.
Fat Necrosis.
H&E,
3
193
Fat necrosis
is a speciF
c type of necrosis seen in
fatty
, or
adipose
,
tissue
. Dam-
age to adipocytes causes release of lipids and cell death followed by aggregates
of foamy macrophages containing the released lipids. ±at necrosis is seen in
damage to fatty tissue by trauma as well as enzymatic digestion as seen in acute
pancreatitis.
Image:
This image shows fat necrosis in subcutaneous adipose tissue after pre-
vious surgery. Note the abundant foamy macrophages containing lipid droplets
(
arrow
).
Liquefactive Necrosis.
H&E,
3
48
Liquefactive necrosis
may be seen after bacterial infections or infarcts involving the
central nervous system.
Image:
This image shows liquefactive necrosis in an infarcted area of the brain.
Note the intact white matter in the
lower portion
of the image and the granular
liquefactive necrosis in the
upper portion
of the image.
Scar.
H&E,
3
16
A
scar
, or
cicatrix
, is the result of a complex healing process involving an ini-
tial infl ammatory response followed by the formation of new blood vessels, tissue
remodeling, and wound contraction. Abnormal healing processes include keloid
formation and hypertrophic scars.
Image:
This image shows a dermal scar characterized by horizontal collagenous
bands and an absence of skin adnexa–like hair follicles.
Necrosis
Necrosis
represents the death of living cells due to irreversible cell injury. Depending
on the tissue involved, necrosis will assume one of several morphologic patterns asso-
ciated with the processes involved in cell death.
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