Pityriasis Lichenoides

ICD-11

LB16

Pityriasis lichenoides chronica (Parapsoriasis guttata)(PLC): LB161.

Pityriasis lichenoides et varioliformis acuta (PLEVA): LB160.

Synonyms

PLEVA: Mucha-Habermann disease.

Epidemiology

PLEVA: Children and adolescents.

PLC: young adults M>F.

Definition

Acute (PLEVA), subacute or chronic erythemato-squamous or -papulo-necrotising (PLEVA) diseases; nosologic relationship to vasculitis and to lymphomatoid papulosis (LyP; spontaneously regressive papular-necrotic form of CTCL).

Aetiology & Pathogenesis

Unknown. Viral (Epstein-Barr and other viruses) and other infectious agents (upper respiratory tract) discussed as trigger factors.

Signs & Symptoms

PLC: Lenticular, erythematous, macular or papular lesions with scaling.

PLEVA: Disseminated, small papules and plaques with scaling or superficial crust, sometimes hemorrhagic. Development to necrotic lesions and healing with varioliform scarring.

Localisation

Predominantly trunk> extremities

Classification

Variable: acute (PLEVA), subacute or chronic.

Laboratory & other workups

Looking for infections (upper respiratory tract), blood picture, biopsy.

Dermatopathology

Depending on acuity

PLEVA: Focal hyperparakeratosis; apoptosis of single keratinocytes; interface-dermatitis (edema in the epidermal-dermal junction with vacuolization of basal keratinocytes); lymphocytic (wedge shaped) infiltrate in the dermis and extravasation of erythrocytes.
PLC: Like in PLEVA, but less prominent.

Course

Weeks or months; maximum of 2 years.

Complications

None.

Diagnosis

Clinical and histologic findings.

Differential diagnosis

Psoriasis guttata, secondary syphilis, varicella, vasculitis, drug reaction.

Prevention & Therapy

No prevention. Skin care, prevention of superinfection; erosive lesions may be treated topically with combined antibiotic-glucocorticosteroid (grade I) cream.

1.5.2 Pityriasis Lichenoides