PITYRIASIS
RUBRA PILARIS
(PRP)
Etiology
• The etiology is unknown
• A familial form of the disease exists, with
an autosomal dominant inheritance
pattern; however, most cases are sporadic
• One hypothesis is that pityriasis RPR may
be related to an abnormal immune
response to an antigenic trigger
• Case reports have described PRP
occurring after streptococcal infections
• The incidence has been reported to be 1
case in 3500-5000 patients presenting to
dermatologic clinics
• PRP occurs equally among men and women
• The familial form typically begins in early
childhood
• The acquired form has peaks in the first and
fifth decades of life, but it can begin at any
age
Clinically
• The familial form of PRP has a gradual
onset, whereas the acquired form has an
acute onset
• The disease
typically spreads in
a craniocaudal
(from head to body)
direction
• PRP is characterized
by orange-red or
salmon-colored scaly
plaques with sharp
borders, which may
expand to involve the
entire body
• A characteristic
feature is presence
of islands of
unaffected skin within
the plaques
• The plaques are formed of follicular
hyperkeratotic papules
• Palmoplantar keratoderma occurs in most
patients and tends to have an orange hue
• Painful fissures may develop in patients
with palmoplantar keratoderma
• Nail changes include distal yellow-brown
discoloration, subungual hyperkeratosis,
longitudinal ridging, nail plate thickening, and
splinter hemorrhages
• Mucous membranes: Patients may complain
of pain and irritation in the mouth. Mucous
membrane changes include a diffuse whitish
appearance of the
buccal mucosa, lacy
whitish plaques,
grayish-white papules
and plaques, erythema,
or possible erosions
• Pruritus, although not a major symptom,
may occur in the early stages of the
disease
Griffiths classification
Type
C/P
I-Classic
adult (>50
of cases)
As mentioned
before
II-Atypical
adult (5%
of cases)
Follicular hyperkeratosis and
ichthyosiform
lesions on the
legs, sparse
scalp hair
Distrib.
Generalized
Generalized
Course
Often
resolves
within an
average of
3y
Long
duration
(> 20 y)
Type
C/P
Distrib. Course
III-Classic Similar to type I GeneralOften
juvenile
but appears in ized
resolves
(10 of
year 1 or 2 of life
within an
cases)
average of
1-2 y
Type
IV- Circumscribed
juvenile
(25% of
cases)
C/P
Distrib.
Prepubertal
Localichildren; wellzed
demarcated scaly,
erythematous
plaques on the
elbows and knees,
resembling
localized psoriasis
Course
Some
cases
clear in
the late
teens
Type
VAtypical
juvenile
(5% of
cases)
C/P
Distrib. Course
Begins in first few Generyears, accounts for alized
most familial cases;
follicular
hyperkeratosis,
scleroderma-like
appearance of the
hands and feet
Chronic
course
Histopathology
• Folliculat Plugging:
The follicles are filled
with dense, horny
(keratinous)plugs
• There are foci
of parakeratosis
in the perifollicular shoulder
and in the epidermis between
the follicles
• At other sites, a basket-weave hyperkeratosis overlies a prominent granular layer
and there is little parakeratosis
•Although the epidermis is acanthotic, it is not,
as in psoriasis, thinned above the dermal
papillae, and there is no tendency for
polymorphs to invade the epidermis
•There is a dermal
infiltrate of
lymphocytes
and histiocytes
Treatment
• Currently, oral retinoids are the first line of
therapy. Isotretinoin has been reported to be
of value, although a comprehensive review
suggests that acitretin (0.5 to 0.75 mg/kg
per day) may be more effective in clearing
lesions. Accordingly, most patients are
treated first with acitretin today
• Therapy with methotrexate(10 to 25 mg
weekly, intramuscularly or orally, in divided
doses, once a week) has shown variable
rates of success
• Some cases respond well to
photochemotherapy, some may flare, and
others require combination treatment with
retinoids or methotrexate
• Several cases of adult-type PRP showed
significant clearance in 2 to 4 weeks with
cyclosporine(5 mg/kg/day) Although most
studies show lack of efficacy
• Some patients are helped by azathioprine
(100 to 150 mg/day) , but this effect is also
inconsistent