Page 148 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-63 Integumentary System

HISTOPATHOLOGICAL FEATURES AND TYPICAL DISTRIBUTION OF PSORIASIS

Munro micro-
abscess (sterile)
made of Surface “silver” scale
neutrophils
Erythematous base

Persistence of nuclei in stratum corneum
(parakeratosis)
PSORIASIS
Increased mitotic activity indicative
of high cell turnover rate
Psoriasis is an autoimmune disease that affects 1% to
2% of the U.S. population. There is a large regional
variation in the incidence of psoriasis. Scandinavian Elongated rete pegs and dermal papillae
countries have a much higher incidence than the rest of
the world, and the Native American population has one Dilation and tortuosity of papillary vessels
of the lowest rates of psoriasis. Much has been learned
about the pathogenesis of psoriasis, and dramatic
advances in therapy have helped many patients. Psoria-
sis is grouped with the other papulosquamous skin dis- Edema and
eases. It can cause not only skin disease but also joint inflammation
disease. The total effect that psoriasis has on patients of dermis
cannot be judged solely on the basis of skin involve-
ment, because the disease has been shown to have pro- Increased number of Langerhans cells
found psychological and social effects as well. There is
no known cure for psoriasis, but research is moving
forward, and new therapies are being developed.
Clinical Findings: Psoriasis is a papulosquamous
skin disease that can affect people at any age of life. Nail pits
There is no gender predilection. Approximately 40%
of affected individuals have a family history of psoria- Transverse ridges
sis. Most patients with early age at onset tend to have
a more severe course of disease. Psoriasis often starts
with silvery, ostraceous, scaly patches and plaques with Onycholysis
a predilection for the knees, elbows, and scalp. The
term ostraceous scale refers to the oyster shell–like
appearance of the hyperkeratotic scale that is oriented Typical appearance Scalp
in a concave manner. The term rupioid scale is used to of cutaneous lesions
describe the psoriatic plaques that appear to mimic the (silvery, scaly plaques)
cone shape of limpet shells. A characteristic clinical Groin and genitalia
finding is that of Woronoff’s ring, the peripheral rim
of blanching seen around the early psoriatic plaques.
Auspitz’s sign is another characteristic clinical sign
used to differentiate psoriasis from other rashes. It
refers to the pinpoint bleeding that occurs after the
upper scale has been removed from a psoriatic plaque. Elbow Knee
Woronoff’s sign is specific to psoriasis and most likely
is caused by localized vasoconstriction surrounding the Sacrum
area of the lesion, which has an increased blood flow.
There is a striking symmetry to the rash. Psoriasis can
have various skin morphologies. There are many well-
recognized clinical variants with distinctive clinical Hand and nails
findings.
Psoriasis vulgaris is the most common form of pso- Intergluteal cleft Nail
riasis encountered. It manifests with symmetrically Typical distribution primarily on extensor surfaces
located, silvery, scaly patches and plaques on the
scalp, knees, elbows, and lower back. Patients can have
a small amount of body surface area involvement, or
they can have widespread disease approaching near-
erythroderma. The face is usually spared from patches Inverse psoriasis is a well-recognized clinical variant Candida infection. Inverse psoriasis is also symmetric in
and plaques of psoriasis. Patients with a higher body that manifests in intertriginous areas of the groin, nature and can present therapeutic challenges.
surface area of involvement tend to have a higher risk gluteal cleft, axillae, and umbilicus. The patches tend Guttate psoriasis is a variant of psoriasis that can
for development of psoriatic arthritis and psoriatic nail not to be as thick as in the other forms, and the scale occur after an infection, most notably a streptococcal
disease. All patients with psoriasis exhibit the Koebner is fine. This is due to their location in occluded areas, bacterial infection. The guttate lesions develop soon
phenomenon. Koebnerization of psoriasis occurs when which have an increased amount of moisture and help after or during the infection and appear as tiny teardrop-
a previously normal area of skin is traumatized and to keep the scale to a minimum. The patches can be shaped patches with fine adherent scale. The word
psoriatic plaques develop within the traumatized skin. bright red and are often misdiagnosed as a cutaneous guttate means “droplet,” and the lesions of guttate

134 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS