Psoriasiform Lesions

Some things common

Epidermal hyperplasia

Elongation of rete ridges

Psoriasis

Psoriasis

Greek word for 'itch'

“chronic

non-infectious

erythematous plaques & papules

silvery scales

extensor distribution”

Psoriasis vulgaris

(common)

Chronic RelapsingPapulosquamous dermatitis

Incidence : 2 %

All Races

More in western people

Mean age - 25 yrs

Chr - 6P21.3

Associated with - HLA-CW0602

(PCR)

How the patient presents ?

Erythematous plaques with

Silver scaling

When the scales are removed …

It bleeds

Auspitz’s sign

Capillaries

Scratch

Which sites are involved ?

Scalp ,

Lips no involved

Oral lesions are rare

5 % cases --- Polyarthritis

Do we know the Cause ?

Trigger factors

TraumaInfectionDrugs : Lithium, iodine , B blockers, Carbamazepine, NSAIDS, ACE inhibitorsClimateHormone, Stress AlcoholSmoking

Lesions after Trauma

(Koebner phenomenon)

30 % cases.

What is the Pathogenesis ?

YY YIts an Immune reaction

“Problem in signal transduction”

Initiation

Cytokine

transcription regulation

problems

Stimulation of immunity by

super antigen

• Problem in signal transduction in between the cells

• Cytokine transcription regulation problems

• Stimulation of immunity by super antigen

Initiation

Blood vessels in the papillary dermis

Disease process starts here

Blood vessels in the papillary dermis

Dilatation and tortuosity

Angiogenesis (TGF alfa, IL 8 )

Size of microcirculation Expands

New vessels bring T lymphocytes

Lymphocyte recruitment in papillary dermis

(PAF, LB4)

Lymphocytes come and bind to endothelial

cells in venules of papillary dermis

Even the expression of

adhesion molecules is

increased (E selectin)

E selectin correlates with the disease process UV rays decrease adhesion molecules! (PUVA therapy !!)

Now the Lymphocytes come out

of the venules (C5a)

CD4 or CD8 ?

CD4 in the dermis

CD8 migrate to the epidermis

Mechanism

T cell activation by super antigen

Release of huge quantity of cytokines

Transit time change

53 days

in Psoriasis

7 days

Histopathology

Early changes

Dilatation and congestion of vessels

Mild perivascular lymphocytic infiltration