Parapsoriasis-Group

Synonyms

None

Epidemiology

Rare. Second half of life (>50 years).

Definition

The clinical picture in some cases remains of psoriasis, without any etiopathogenetic relationship. However, there is a nosologic relationship to mycosis fungoides or other CTCL.

Aetiology & Pathogenesis

Unknown.

Signs & Symptoms

SPP: Small red-brown, indolent (no itch), slightly scaling macules (1-2 cm), following the splitskin lines.

LPP: large geographic irregular but sharply demarcated, slightly scaling macules or plaques; no itch.

PAV: Mottled slightly (pityriasiform) scaling erythematous patches.

Localisation

SPP: predominantly trunk; skin split lines.

LPP: predominantly trunk and upper extremities.

PAV: trunk or total skin.

Classification

Small Plaque Parapsoriasis: usually no evolution into CTCL.

Large Plaque Parapsoriasis: potential precursor of CTCL (mycosis fungoides).

Poikiloderma atrophicans vasculare: potential precursor of CTCL (mycosis fungoides).

Laboratory & other workups

No special, biopsy.

Dermatopathology

Subtle eczematous changes of the epidermis with a few lymphocytes in the dermis and the epidermis. No band like infiltrate in the papilary dermis. No lymphocyte microabscesses in the epidermis.

Course

Chronic over years or decades. Follow-up mandatory because of potential development of mycosis fungoides.

Complications

LPP and PAV may develop to CTCL, preferentially mycosis fungoides (years or decades).

Diagnosis

Clinical picture, histopathology and course.

Differential diagnosis

Atopic or seborrheic eczema, CTCL subtypes in particularmycosis fungoides, tinea corporis, pityriasis versicolor.

Prevention & Therapy

Prevention not possible. Topical therapy: photo-(helio-) or photochemotherapy. Glucocorticosteroid-cream temporarily.

3.3.11 Parapsoriasis-Group