Page 149 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-64 Rashes

INVERSE PSORIASIS AND PSORIASIS IN THE GENITAL AREA

PSORIASIS (Continued)

psoriasis appear as tiny droplets of psoriatic patches
found generalized over the skin, as if areas of psoriasis
had developed within sprinkled water droplets. Chil-
dren with guttate psoriasis may have only one isolated
episode after a streptococcal infection and no evidence
of psoriasis thereafter. Adults with guttate psoriasis, on
the other hand, almost always develop psoriasis vulgaris
at some later point. Thick, adherent, silvery, scaly
Scalp psoriasis is a unique variant that occurs only on patches and plaques on scalp
the scalp. Patients complain of thick, scaly patches that
itch and can cause a dramatic amount of seborrhea.
Most patients who present with localized scalp psoriasis
eventually develop areas of psoriasis elsewhere on their
bodies.
Pustular psoriasis is a rare and distinctive form. It can
occur in patients with a preexisting history of psoriasis,
or it can be the initial presenting morphology. The
diagnosis is straightforward in a patient with a long-
standing history of psoriasis who develops a pustular
flare. The most common reason for this is the rapid
withdrawal of systemic corticosteroids, for example,
when a patient with psoriasis is prescribed methyl-
prednisolone for some unrelated condition, such as Typical
allergic contact dermatitis due to poison ivy. The rapid appearance
decrease in the dose of the corticosteroid can induce a of intertriginous
pustular flare. The patches of psoriases develop pin- Inframammary, axillae, umbilicus, groin, and gluteal lesion
point (1-2 mm) pustules that can coalesce into superfi- cleft are regions involved in inverse psoriasis.
cial pools of pus. These patients are often ill appearing
and can have associated hypocalcemia. Patients present-
ing with pustular psoriasis without a preexisting history
of psoriasis pose a difficult diagnostic problem at first.
The differential diagnosis is among psoriasis, a pustular
drug eruption, and Sneddon-Wilkinson disease. A skin
biopsy and clinical follow-up will eventually make the
diagnosis clear. Regularly spaced
Nail psoriasis is most often associated with severe and shaped
psoriasis vulgaris and psoriatic arthritis. It can occa- acanthosis of the
sionally be a solitary finding. Oil spots, onycholysis, epidermis, with
nail pitting, and variable amounts of nail thickening telangiectatic
can be present. Nail disease is refractory to most topical vessels in the
therapies, and often systemic therapy is required to papillary dermis
get a good clinical response. Nail psoriasis is a marker
for psoriatic arthritis, and patients with nail psoriasis
are at a higher risk for development of psoriatic
arthritis.
Palmar and plantar psoriasis is another of the less
commonly seen clinical variants. It can manifest on the
palms and soles as red, scaly patches and plaques or as
patches studded with a variable amount of small pus-
tules. This variant of psoriasis is more commonly found
in females, and smoking has been shown to make the
clinical course worse.
Psoriatic erythroderma is a rare variant that is seen
as a sequela of steroid withdrawal or of other, undefined findings. Patients typically present with an asymmetric Pathogenesis: Psoriasis is an autoimmune disease
triggers. It manifests with near-total redness of the skin. oligoarticular arthritis, a symmetric polyarticular arth- caused by an abnormality within the cells of the immune
The redness is caused by massive vasodilatation of the ritis, distal interphalangeal–predominant disease, spinal system. There is a genetic susceptibility, and the human
cutaneous vasculature, which can lead to high-output spondylitis, or arthritis mutilans. Arthritis mutilans is leukocyte antigen (HLA) Cw6 locus is the most com-
cardiac failure. These patients are universally treated in the rarest form of psoriatic arthritis, but it is life altering monly found (but not the only) susceptibility factor
the inpatient setting. and can lead to a devastating loss of function. Psoriatic in patients who develop psoriasis. The success of
Psoriatic arthritis can manifest in association arthritis is considered to be a seronegative form of therapy with cyclosporine, a medication that dramati-
with psoriatic skin disease or as arthritis with nail inflammatory arthritis. cally decreases T-cell function, was one of the first

THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS 135