Chapter 30 :: Pityriasis Lichenoides(苔蘚樣糠疹)
:: Stefan M. Schieke & Gary S. Wood
鄭煜彬(20200114)
PITYRIASIS LICHENOIDES(PL)
PITYRIASIS LICHENOIDES(PL)
EPIDEMIOLOGY
|
|
What age group has higher prevalence
rate of PL?
|
Children & young adults
|
Which season has higher prevalence of PL?
|
Fall and winter.
|
How much is the male-to-female ratio of PL?
|
1.5~3: 1(M>F)
|
Which one is more common, PLC or PLEVA?
|
PLC, which is 3 to 6 times more common
than PLEVA.
|
CLINICAL FEATURES
|
|
What is the divide of PLC & PLEVA?
|
No, they are in a spectrum, and usually
coexist.
|
What is the symptoms of PL?
|
Asymptomatic> pruritic or burning
|
What is the features of PLC?
|
Recurrent crops of erythematous scaly papules, regressing over
several weeks to months
|
What is the features of PLEVA?
|
Recurrent crops of erythematous papules with crusts, vesicles, pustules, erosions,
or ulcers before regressing in weeks (shorter than PLC)
|
What feature determine the duration of PL
in children?
|
Distribution(not the number of lesions)
|
What distribution of PL has longer
duration?
|
Peripheral (distal extremities) > central (trunk)
> diffuse
|
What is the “clinical pattern” of PLC
& PLEVA individually?
|
PLC: papulosquamous lesions (scaly
papules)
PLEVA: papulonecrotic lesions (papules
with ulcer)
|
What is PLEVA with severe ulceration
& fever?
|
Pityriasis lichenoides with
ulceronecrosis & hyperthermia (PLUH) or febrile ulceronecrotic
Mucha–Habermann disease (FUMHD)
|
What is the features of PLUH?
|
Fever, purpuric papulonodules with central
ulcers up to several cms (larger than PLEVA/PLC)
|
What is the common locations of PL?
|
Trunk & proximal extremities (all skin/mucous
membranes is possible, regional/segmental lesions also exists)
|
What is the common skin sequelae of PL?
|
Postinflammatory hypo/hyper-pigmentation
|
What disease does the remnant of PLC look
like?
|
Idiopathic guttate hypomelanosis (PLC left postinflammatory hypopigmentation actually)
|
What disease does the remnant of PLEVA
look like?
|
Smallpox-like scar
|
What is the difference between smallpox
& PLEVA?
|
Smallpox: all lesions are in the same
stage
PLEVA: in various stages of evolution
|
COMPLICATIONS
|
|
What is the most common complication of
PL?
|
Secondary infection
|
What is the complications of PLEVA?
|
Low-grade fever, malaise, headache, and
arthralgia (like a mild flu)
|
What is the complicatiolns of PLUH or
FUMHD?
|
High fever, malaise, myalgia, arthralgia,
gastrointestinal, & CNS symptoms(like a severe
flu, can be fatal)
|
What is the relationship of PL & lymphoma?
|
Almost no relationship. (Only very rare
cases progress to MF)
|
ETIOLOGY
|
|
What could cause PL?
|
Unknown, can be infections(toxoplasma
gondii & virus), estrogen-progesterone therapy, chemotherapy,
radiocontrast iodide, influenza vaccine, & HMG-CoA reductase inhibitors.
|
What is the Immunohistologic difference between
PLC & PLEVA?
|
PLEVA: CD8+ T cells with TIA-1 & granzyme B(cytotoxic) predominate
PLC: CD4+ T (helper) predominate, CD8+ T, FoxP3+ T (regulatory) |
What is the difference of clonality between
PLC & PLEVA?
|
PLEVA: half cases have clonality
PLC: minority has clonality
|
What is the possible pathogenesis of PL?
|
Clonal cytotoxic memory T-cell
lymphoproliferative
response to one or more foreign antigens.
|
Which disease has most overlapping
features with PL?
|
Lymphomatoid papulosis (LyP)
|
What is the difference between PL &
LyP?
|
l LyP (type A & C): large CD30+ atypical lymphoid cells.
l LyP has CD4+ cells which lack 1 or more mature T-cell
antigens(CD2, 3, & 5)
|
DIAGNOSIS
|
|
How to diagnose PL?
|
Clinical & pathological features.
Blood test may show leukocytosis &↓CD4/CD8, but of little value.
|
PATHOLOGY
|
|
What are the common pathological features
of PL?
|
An interface dermatitis of lymphocytes (denser
& more wedge shaped in acute lesions), exocytosis, parakeratosis, &
RBC extravasation.
|
What features may appear in acute
variants of PL?
|
1.
Necrotic keratinocytes/vesicles/pustules/
ulcers.
2.
Lymphocytic vasculitis + fibrinoid
degeneration
|
What is the meaning of CD30+ variant of
PLEVA?
|
PL serve as fertile soil for the
development of the CD30+ T-cell clone characteristic of lymphomatoid
papulosis/ anaplastic large cell lymphoma
|
DIFFERENTIAL DIAGNOSIS
|
|
What is the differential diagnoses of PL
and the method to distinguish them?
|
l Secondary syphilis & virus exanthemas (serology)
l LyP(CD30+ large atypical lymphoid cells)
l Macular/papular variants of MF(small epidermotropic atypical lymphoid cells with convoluted
nuclei & a band-like superficial dermal lymphoid infiltrate)
|
MANAGEMENT
|
|
When should PL be treated?
|
The more acute course(PLEVA) & severe
lesions (PLUH)
Mild, chronic lesions can be ignored.
|
How to treat PL?
|
l Topical steroids & photo/photodynamic therapy
l Systemic (antiinflammatory) antibiotics: tetracyclines,
erythromycin, & azithromycin
l Systemic steroids, low-dose methotrexate, calcineurin
inhibitors(tacrolimus) & retinoids(bexarotene)
l Bromelain (a pineapple extract, very effective)
l Antibiotics for Gram(+) pathogens in secondary infections of PL
lesions
|
No comments:
Post a Comment