CHAPTER 4
Connective Tissue
69
CLINICAL CORRELATION
Figure 4-13C.
Actinic Keratosis.
H&E,
3
205
Actinic keratosis
, also called
solar elastosis
, is a degenera-
tive skin condition, which mainly affects the
collagen
and
elastic f
bers
of the sun-exposed areas of the body. Frequent
exposure of the skin to sunlight or ultraviolet light causes
and accelerates this degenerative process. Actinic keratosis
is a premalignant lesion. Signs and symptoms include loose,
wrinkled, dry, and sagging skin. Histologically, the amount
of
collagen f
bers
present in the affected skin is decreased,
whereas the amount of
elastic f
bers
increases, but they lose
some of their elasticity and fl
exibility. A bluish discoloration
of the papillary dermis is characteristic of ultraviolet dam-
age to the connective tissue of the dermis.
Dermal
atrophy
and
loose collagen f
bers
are illustrated here. Avoiding
unnecessary sun exposure is the most important prevention.
Treatment includes liquid
nitrogen cryotherapy, surgical
curettage, and chemotherapy.
Blood vessel
Collagen
fibers
Fibroblasts
A
Figure 4-13A.
Dense irregular connective tissue, mammary
gland.
H&E,
3
272
Dense irregular connective tissue
can be found in the
mammary
gland
and also in other places such as capsules of organs. In
this example, dense irregular connective tissue in the mammary
gland is shown, distributed in between glandular tissues.
Colla-
gen f bers
predominate, appear pink, and are arranged in wavy
bundles without a consistent orientation.
Fibroblasts
are visible
among these ±
bers. Occasionally,
blood vessels
and glands can
be found in dense irregular connective tissue; however, dense
irregular connective tissue is generally not a richly vascularized
tissue.
Elastic fibers
Elastic fibers
Elastic fibers
Elastic fibers
Collagen fibers
Collagen fibers
Collagen fibers
Collagen fibers
Glands
Glands
Elastic fibers
Elastic fibers
Collagen fibers
Collagen fibers
Glands
B
Figure 4-13B.
Dense irregular connective tissue, dermis o±
the skin.
Elastic stain,
3
68; inset
3
151
Collagen f bers
are arranged in randomly oriented bundles and
appear pink here; they are the principal ± bers in
dense con-
nective tissue
. Collagen ±
bers are fl
exible and have a high ten-
sile strength.
Elastic f bers
are made visible with a special stain
and are seen as thin, dark strands scattered among the collagen
± bers. They have the ability to stretch and return to their origi-
nal length. Dense irregular connective tissue is a cushionlike
tissue, which provides great strength against
pressure-induced
stresses
on structures or organs.
Dermal
atrophy
Loose
collagen
fibers
C
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