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In Depth Tutorials and Information
FIGURE 30.1
Histology of the skin showing three tissue layers: epidermis, dermis, subcutaneous tissue.
Courtesy of Dr. Janis Taube.
and subcutaneous fat contribute layer by layer to the
structure and function of skin.
CUTA
NEOUS MANIFESTATIONS
OF OI
OI is a heterogeneous disease that presents with
marked variation in clinical features, inheritance patterns
and mutated genetic loci. Accordingly, dermatologic find-
ings can vary widely among individuals, but are most
prominent in OI types I and IV (please refer to Chapter 2
for discussion of OI subtypes).
10
The major skin features
of OI related to collagen loss include thinness, fragil-
ity and translucency.
11
A recent report found that skin in
individuals with OI was generally stiffer and less elastic;
OI skin had on average 2 mm less distensibility and 56%
less elasticity than that of normal controls.
12
Defects in dermal collagen adversely affect recov-
ery from trauma in OI skin. Poor wound healing leads
to broad atrophic scars and higher risks of infection,
which are of particular concern following surgical pro-
cedures.
13,14
OI patients are also more likely to bruise
secondary to abnormal platelet function secondary
to defective release of platelet factor 3 and abnormal
aggregation to ADP.
15
Additionally, OI increases sus-
ceptibility to hypermetabolic states, which can present
with hyperhidrosis, tachycardia and tachypnea.
16
A
case series of 29 patients found 30% experienced exces-
sive sweating.
17
Another hallmark of skin in OI is elastosis perforans
serpiginosa (EPS) or hyperkeratotic papules that form
as a consequence of elastic fiber elimination through the
epidermis (
Figure 30.2
). These papules are often grouped,
circular, serpiginous, linear or arciform patterns on the
neck, face or upper trunk and extremities.
18,19
In sum, OI
FIGURE 30.2
Clinical and histopathologic appearance of EPS.
(A) Clinical presentation of EPS forming a circular pattern on the
upper extremity. (B) Histology representative of EPS showing focal
areas of hyperplastic epidermis with perforating channels contain-
ing fragmented elastic tissue and nuclear debris.
B reproduced with copyright permission from Elsevier.
skin may display variable degrees of thinness, fragility,
easy bruisability, atrophic scars and EPS.
PATHOPHYSIOLOGY OF DERMATOLOGIC
FINDINGS IN OI
Defects in collagen type I, the most abundant compo-
nent of dermal connective tissue, underlie the dermato-
logic changes in OI. Approximately 85% of patients with
OI have mutations in type I collagen genes
COL1A1
or
COL1A2
that code for the α1- and α2-chains. Abnormal
α-chains are more susceptible to deficient procollagen
