(Last Updated On: )


  • Psoriasis is an inflammatory dermatosis of the skin, characterized by chronic erythemaomatic lesions
  • It is common (2% of the population), it occurs at any age, especially in young adults (between 20 and 30 years of age)
  • It is a benign dermatosis but which greatly impairs the quality of life
  • Diagnosis is essentially clinical
  • There are severe forms: erythrodermia, psoriatic arthritis, pustular psoriasis
  • Its pathophysiological mechanisms are imperfectly known
  • Treatment is symptomatic, often based on local therapies. General treatments, used exceptionally, are reserved for severe forms
  • Aggravating factors: stress, infection, medication


  • Psoriasis is characterized by an acceleration of epidermal renewal, in fact, the turn over epidermal (which is normally 30 days) is only 7 days in psoriasis, this is related to immune disorders (activation of LT and secretion of the different cytokines: TNF, IL12, IL23…) resulting in a psoriatic inflammatory reaction responsible for the increased proliferation of keratinocytes
  • It is a multifactorial condition:

Genetic factor: 30% of psoriatics are familial, when the condition begins in childhood, it is frequently linked to histocompatibility antigens (HLA Cw6)

Environmental factors:

  • Alcohol and tobacco are factors of resistance to treatment
  • Infections are highlighted especially in childhood psoriasis flare-ups
  • Psychological factors and medications (lithium salts, blockers, IEC…) can induce or aggravate psoriasis


  • Classic form of vulgar psoriasis:

Elemental injury: it is a scaly erythemato stain

  • Surface scaly layer: whitish and dull, smooth or rough, slightly raised compared to nearby healthy skin. These dander are dry, of varying size and thickness, can completely or partially mask the rash. Brocq's methodical scratching reveals:

Bleaching sign: the first strokes of curettes remove the crumbly surface layers and the surface becomes a bright white

Sign of the candle stain: the deep layers are more consistent, have a micacéd appearance

Sign of the sticky film: tearing a thin film sticking to the deep plane

Sign of the bloody dew (Auspitz sign): it is the appearance of thin hemorrhagic droplets, reflecting the stripping of dermal taste buds

  • Erythematous stain: located under the scaly layer, characteristic pink color, congestive red (at the lower limbs), although limited, smooth and dry, flexible, disappears at vitropression

Grouping and topography:

  • Number: rarely isolated plaque psoriasis, most often, multiple or diffuse
  • Dimensions:

In a "punctata" point or in "guttata" drops a few millimetres in diameter, this is an eruptive psoriasis of the child, sometimes preceded by an infectious ENT episode

Nummular (nummulus – coin) a few centimetres in diameter

In plaque, more or less geometric or circumcised contours

Universalis: widespread, affecting almost all of the teguments

  • Topography: very evocative of the diagnosis (in terms of bone protrusions), although ubiquitous, often sits on surfaces exposed to trauma (elbows, cubital edge of the forearm, knees, pretibial regions, lumbar regions, leather hair, nails)

Functional signs (pruritus): Psoriasis is generally low or not pruriginous

  • Special clinical forms:

Topographic forms:

  • Psoriasis of the scalp: it achieves either erythemato-scaly plaque lesions (well limited, covered with large dry dander, crossed by the hair, without alopecia) or a real shell covering the entire scalp
  • Psoriasis of the folds (inverted psoriasis): it is a continuous plaque, red, shiny and smooth, little or not scaly, seat at the fold inter-fessier, inguinal, genital region, submammary, hollow axillary …
  • Facial psoriasis: rare, it can take on the appearance of seborrheic dermatitis (sebopsoriasis)
  • Palmoplant psoriasis: often bilateral, it can achieve an islet keratodermy or diffuse
  • Nail psoriasis: 30-50% of psoriasis cases, sometimes isolated, appearance of cutuliform punctuated depressions (nails in "sewing dice"), onycholysis with distal detachment, sub-ungueal hyperkeratosis, leuconychia
  • Psoriasis of the mucous membranes:

On the acorn: very limited spots, purely erythematous

On the tongue: geographical language especially in pustular psoriasis, scrotal tongue

Child Psoriasis: May be early – psoriasis of napkin psoriasis, in children, often acute, in drops and may be a successor to a strep throat infection. The face is more often affected than in adults

Psoriasis caused:

  • Medications: they may induce or aggravate psoriasis or be responsible for resistance to treatment (lithium salts, blockers, INF)
  • Koebner phenomenon: characterized by the appearance of psoriasis lesions on a skin trauma: scratching streaks, surgical or post-traumatic scars

Serious forms:

  • Erythrodermic psoriasis: generalized psoriasis to more than 90% of teguments, with abundant flaking, erythrodermia can be caused by general corticosteroid therapy, it can be complicated by overinfection,  thermoregulation and hydroelectric anomalies and should lead to hospitalization
  • Pustular Psoriasis: This is an amicrobial pustulose, it can appear right away or on a psoriasis already known and can be triggered by various medications (especially general corticosteroid therapy). It distinguishes:

Localized palmoplanet psoriasis: in flare-ups, functional disability is often important

Generalized pustular psoriasis (von Zumbusch): sudden onset with altered general condition, fever and bright red cupboards that are covered with pustules that can confluence into large slicks

  • Arthropathic Psoriasis: affects about 20% of psoriatics, and produces various clinical charts

Arthrals, mono- or trace arthritis or arthritis similar to rheumatoid arthritis with however, a distal interphalangian disease and negative rheumatoid factor

Axial psoriatic rheumatism with spinal and sacroiliac damage adjacent to ankylosing spondylitis

Evolution / Complications:

  • Psoriasis is a chronic disease that develops in flare-ups that vary in duration and is unpredictable in its occurrence. With each push, we notice the reappearance or extension of old plates while new elements may appear
  • During remissions, the stain fades and can disappear completely, sometimes leaving achromic or pigmented after-effects. Remissions are more frequent in the summer (beneficial effect of UV rays)
  • Complications:

Minors: overinfection, eczema, lichenification

Majors: erythrodermic, pustular and arthropathic psoriasis


  • Positive diagnosis: is easy, essentially clinical: chronic erythemato-squamous dermatosis (push/remission) and location of lesions in bastion areas. If in doubt – skin biopsy with histological study:

Epidermal abnormalities:

  • Hyperkeratosis with parakeetosis: thickening of the corneocytes that retain the nucleus
  • Munro-Sabouraud micro-abscess: polynuclear epidermal infiltrates
  • Lowered or absent granular layer
  • Hyperacanthosis: excessive proliferation of keratinocytes

Dermal abnormalities: papillomatosis (elongated dermal papillae) and inflammatory infiltrating (TCD4), a thick basal membrane with highly developed capillaries in the papillae

  • Differential diagnosis: it arises with many erythemato-scaly dermatoses of chronic evolution, we will only quote them: Gibert rosé pityriasis, seborrheic dermatitis, pityriasis rubra pilary, fungal mycosis, chronic eczema…


  • Goals: to achieve a more or less complete transient disappearance of lesions (no curative treatment)
  • Therapeutic weapons:

Local treatments:

  • Dermocorticoids: they are used in ointment (dry lesions), creams are reserved for creases and lotions to the scalp.  Their side effects are numerous and it is advisable to perform limited-time treatments and control the quantities used (number of tubes)
  • Calcipotriol (Daivonex®: derived from vitamin D): it is available in ointment, cream and lotion, its activity is equivalent to that of dermocorticoids (antiproliferative and anti-inflammatory)

Use 2 applications per day without exceeding 100 g/week to avoid the risk of hypercalcemia

Irritative phenomena occur in 20% of cases, especially when on the face

The combination of Calcipotriol and corticothérapie therapy is very effective (Daivobet®: Daivonex – Betamethasone)

Contraindications: pregnancy, kidney failure, patients on vitamin D or calcium

  • Other topical treatments:

Keratolytics (salicylic acid at the concentration of 2-5% in a "Vaseline" fatty excipient, urea at 10-20%): are useful in very keratosic lesions

Baths and emollients: are useful for stripping lesions

Tar-based products: cade oil (wood tar), in the form of caditar lotion, to be put in bath water or shampoo

Topical retinoids (Tazarotene): have a significant irritative effect, reserved for very limited psoriasis (< 10% de la surface corporelle) 10%="" de="" la="" surface=""></ 10% de la surface corporelle)>

General treatments:

  • Acitretin (retinoid, derived from vitamin A: Soriatane® or Netigason®): in the form of capsules of 10 and 25 mg, prescribed at the dose of 0.3-0.5 mg/kg/d

Side effects: are dose-dependent: dry skin and mucous membrane (compulsory cheilitis), hepatotoxicity (reversible at a standstill), high cholesterol, hypertriglyceridemia, teratogenic risk (contra-indicated its administration during pregnancy and involves in any woman during period of genital activity the carrying out of a pregnancy test before treatment and the use of reliable contraception started before treatment, continued during treatment and for 2 years after her stop)

Re-PUVA: combination of retinoids and PUVA

  • Methotrexate: the most widely used cytostatic

Form: 2.5 mg tablets and 10, 25 and 50 mg injectable bulb (IM or sub-cut)

Dose: 15-25 mg/week, the effect starts from the 8th week

Side effects: especially hematological and liver effects, require strict monitoring

  • Ciclosporin: powerful immunosuppressive treatment, very effective, but with a significant nephrotoxic risk during prolonged treatments. The initial dose is 2.5 mg/kg/d, it can be increased subject to good clinical (HTA) and biological tolerance (creatininemia) up to 5 mg/kg/d


  • PUVA therapy (photo-chemotherapy): consists of administering 2 hours before irradiation by UVA (320-400 nm) a photosensitizing psoralene (8-methoxypsoralene-Melatonin®) tablet

Side effects: early rash, accelerated skin aging and induction of skin or cataract cancer)

Used at a rate of 3 sessions per week and not to exceed 100-150 j/cm2 for a cure of 30 sessions per year and 100 sessions in life

  • UVB phototherapy (290-320 nm): mainly used in the form of narrow-spectrum UVB (TL-01: 311 nm), phototherapy results in 80% of cases in remission of lesions in 4 to 6 weeks of treatment
  • Thalassotherapy / Crénotherapy: sea baths associated with sun exposure, spas are a good adjuvant treatment

Biotherapy: These drugs are biological molecules (derived from biotechnology), used to block or inhibit specific stages of psoriasis pathogenesis, are anti-TNF or [Étanercept (Enbrel®), Infliximab (Remicade®), Adalimumab (Humira®)]lyphocytic T-targeted by binding inhibition LFA1-ICAM1 [Efalizumab (Raptiva®)]. Their indication is reserved for failures or contraindications of previous systemic treatments

  • Indications: they depend, on the one hand, on the type of psoriasis and, on the other hand, on the patient himself and his quality of life

Localized forms: local treatment is sufficient

Extensive forms: treatment includes: phototherapy and/or retinoids or Methotrexate or Ciclosporin

Special clinical forms:

  • Pustular Psoriasis: Acitretine
  • Erythrodermic Psoriasis: Hospitalization – Local Treatment – Methotrexate or Acitretin
  • Disabling psoriatic rheumatism: Methotrexate or Ciclosporin


Psoriasis is a common, benign disease that can be serious, not only because of its complications but also because of its impact on the patient's quality of life. If the treatments used there are simply symptomatic, the hopes now come through immunomodulatory treatments targeted at the stages of psoriasis pathophysiology

Leave a Reply