الفهرس 
marterial and methodsOnly 14 pages are availabe for public view
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Abstract
The present study was conducted on 60 human beinc,s
comprising 30 psoriatic patients, who stopped tt·eatment for’ 3
weeks, and 30 normal volunteers. For each case~ skin biopsy
was ob~ained and to clarify the hereditary role played in the
pathogenesis of psoriasis, pedigrees cqnstruction,
consanguinity and segregation analysis and chromosomal study
were done. The skin biopsies were stained by Hx, & E. stain;
Van Gieson’s stain, Methyl Green Pyronin IM.G.P.1 stain and
ATPase histochemical method.
Hx & E stain of os or i a e i c skin f’evea I ed f’egul at”’
elongation of the epidermal ridges with
deep portion, elongation and edema of
thickening
the der-rna I
in b b e t rpapillae,
thinning of the suprapapillary portions
Malpighii, parakeratosis and absence of
of the st,-atum
9 t~anu 1at” layer”,
intermingled with orthokeratosis with presence of granular
Iaye,”. Also, Munro microabscesses diagnostic fat”
psor”iasis.
By Van Gieson’s stain. the nuclei appea,”ed black b r-own
to black, and the collagen fibers stained red. There was
thickenning in the epide,”mis of psor-t a t t c skin and coll.agen
fibers in the dermis appeared more condensed and thet”e was
Increase in the numbet’ of fibroblasts;~uclei.T·his slJqgested an
increase in the activity of psoriatic fibroblasts.
By M. G. P. stain. the RNA of cytop lasm appea.’ed ”ed and
nuclear DNA appeared blue green. The amount of DNA and RNA
increased in the epidermis of psoriatic skin when compared to
that of normal skin.
By ATPase histochemical staining method. the L. Cs.could
be demonstrated and appeared as dendritic cells, polygonal to
oval cells, or as dendritic fragments. Normal skin showed the
cells as continuous network in the suprabasal Malpighian layer
and they were demonstrated in hair follicles. The cells were
nevet”’ seen in the stratum corneum. No cells could
demonst.’ated in the dermis but they were confIned to
be
the
ducts of sweat glands.
In psoriatic 5pecimens,howevet’, the dlstt”’ibution of L.
Cs. alte.’ed completely f rom that of rror-ma l skin. In 20 cases,
large segments of the epidermis were totally de~oid of L. Cs,
though their distribution in hair follicles was conserved. In
the remainder 10 cases, there was abnormal clustering of.L. Cs.
in the epidermis and groups of ATPase +ve cells were found at
any level of the epidermis and frequently at the tip of dermal
papillae and in dermal papillae themselves. Also, L. Cs.
reached the stratum corneum. In the dermis of psoriatic
clusters of L. Cs.could be demonstrated and clusters also
appea,’ed in the dermal papillae. The mean number of L.Cs /
449:’:10.4
2 mm
was 455 ±11.6 in normal male skin and in rior-ma I
female skin. Thet·e was no sex difference of L. • Cs· density. The
mean number” of LCs/mm2 in psot’’’iatic male skin was 112!1’7.1 and
114-18.2 in psoriatic female skin .The density of L. Cs. was
significantly decreased in psoriatic skin at P <0.001
Genet.ic st.udy revealed t.hat. : Consanguinity was not
found to have any ”ole in the development of
psoriasis. Positive family history was t’ecor’ded in 20% of
cases.Segt’egation analysis revealed that pso,’iasis is genetic
dependent and the mode of inher’itance was found to be
multifactorial as it did not follow any simple monogenic type
of inheritance neither autosomal dominant rior- r e c e s s i ve n o rsex
linked iheritance.
The chromosomal st.udy of both c on t r-o I and psot”’iatic
groups revealed no significant difference.
from this stUdy, it could be concluded that psoriasis is
a heredity-dependent and both fibroblasts and L. Cs. may be
contributing factors in the pathogenesis of psoriasis. As the
mode of inrier- i tance is multifactorial, the environmental
factors have a role in precipitating