Psoriasis

PSORIASIS
  • Typical lesions are erythematous (red), raised, scaly, well demarcated plaques
  • Characteristically presents with silvery mica scales.
  • Sites: extensor aspect of trunk & limbs preferentially
  • Due to increased cell turn over resulting in marked epidermal skin thickening (acanthosis)
  • 50% have positive family history
  • Associated with HLA-Cw6 (most common)
  • Deletion of 2 late cornified envelope (LCE) genes, LCE3C and LCE3B, is a common genetic factor for susceptibility to psoriasis
  • Obesity is another factor associated with psoriasis. Weight loss results in significant improvement
Triggering factors
  • Trauma (Koebner phenomenon)
  • Season (worsens in winter)
  • Emotional stress
  • Upper respiratory tract infections
  • Drugs like beta-blockers, lithium and chloroquine
  • Withdrawal of systemic steroids can lead to precipitation of pustular psoriasis.
Variants
  • Plaque type
  • Most common type
  • Slow, indolent course
  • The most commonly involved areas: elbows, knees and scalp
Inverse psoriasis
  • Affects the intertriginous regions including the axilla, groin, submammary region, and navel
  • May be moist and without scale due to their locations
  • Guttate psoriasis (eruptive psoriasis)
  • Most common in children and young adults
  • It develops acutely in individuals without psoriasis or in those with chronic plaque psoriasis
  • Patients present with many small erythematous, scaling papules, frequently after upper respiratory tract
  • infection with β-hemolytic streptococci
Pustular psoriasis
  • Generalized eruption of sterile pustules
  • Fever
  • Intense erythema
  • Local irritants, pregnancy, medications, infections, and systemic glucocorticoid withdrawal can precipitate this form of psoriasis
  • Types
  • Palmo plantar
Acrodermatitis continua
  • Pustular bacterids
  • Generalized pustular (Von Zumbusch disease)
  • Psoriatic arthritis (PsA)
  • Occurs in 5 – 10% of patients with psoriasis. There are five subtypes
  • Symmetric: resembles rheumatoid arthritis, but is usually milder
  • Asymmetric: can involve any joint; present as sausage digits (Pencil in cup or Opera glass deformity)
  • Distal interphalangeal predominant (DIP): the classic form
  • Spondylitis
  • Arthritis mutilans: severe and deforming, affects primarily the small joints of the hands and feet.
  • Scalp psoriasis: Pityriasis amaintaceae
  • Rupoid psoriasis: classically present in Reiter's syndrome (HLA-B 27).
Signs:
  • Auspitz sign -a characteristic finding of psoriasis in which removal of scales leads to pinpoint bleeding
  • Removal of scales reveals a glistening red membrane of Berkeley
  • Grattage Test — on scratching scales appear
  • Wornoff Ring — White halo around lesion
  • Candle grease sign
  •  In nails
  • Onycholysis (separation of nail plate from nail bed)
Thimble-pitting of nail plate
  • Not seen in psoriasis
  • Alopecia
  • Mucosal involvement
  • CNS involvement
  • Histological features
  • Elongation of rete-ridges
  • Parakeratosis
  • Hypogranulosis
  • Munro's micro abscesses in the horny layer
Spongiform pustules of Kogoj
  • The psoriatic epidermis shows rapid transition of epidermal cells in as fast as 2 days as compared to 13 days in normal epidermis
  • Itching may or may not present
  • Key diagnostic points for psoriasis
  • Erythematous scaly plaques
  • Well-defined border
  • Scales dry loose and micaceous
  • Koebner phenomenon seen
  • Auspitz sign positive
  • Regular, circular pits on nail plates
  • Involvement of DIP joints of fingers and toes.
  • Histopathological: Spongiform pustules of Kogoj
Treatment
  • Treatment of choice: PUVA therapy
  • DOC for psoriatic arthropathy: Methotrexate
  • Tar preparations, Vit-D3 analogs like calcipotriol, Anthralin etc... can be used locally
  • DOC in AIDS with psoriasis & pustular psoriasis: Synthetic retinoid — acitretin
  • Biological agents used in the treatment of psoriasis
  • Alefacept (anti-CD2)
  • Etarnacept, Adalimumab, Infliximab (anti-TNFα)
Exam Question
  • Most common site affected by psoriasis is extensor surface.
  • A 24 year old lady with a past history of psoriasis presents with fever and multiple pus filled lesions in a generalized distribution.Methotrexate is the drug of choice. The only definite indication for giving systemic corticosteroids in pustular psoriasis is extensive lesions.
  • The Drug of choice for a pregnant woman in 2nd trimester with pustular psoriasis is Prednisolone.
  • Methotrexate is the drug of choice in the treatment of erythrodermic psoriasis.
  • Lithium, Beta blocker ,Hydroxychloroquine are known to exacerbate psoriasis.
  • Methotrexate used in the treatment of pustular psoriasis acts by inhibiting dihydrofolate reductase.
  • Limpet-like cone-shaped lesions in psoriasis refers to Ruipoid Psoriasis.
  • Nail changes in Psoriasis includes: Pitting: It is the most frequent change ,Subungual hyperkeratosis ,Onycholysis ,Thickening and yellowish discoloration of nail plate, Oil spots. HLA associated with psoriasis is HLA-CW6.
  • A topical retinoid recently introduced for the treatment of psoriasis is Tazarotene.
  • Histopathological features of psoriasis include - compact hyperkeratosis, orthokeratotic stratum corneum supra papillary thinning, Munromicro abscess in stratum corneum , Kogoj's spongiform pustule, exaggeration of rette pattern and parakeratotic stratum corneum (i.e. nuclei are retained) with marked epidermal thickening (but absent or thinned stratum granulosa).
  • Bleeding spots seen on removal of scales in psoriasis is called as Auspitz sign.
  • The important feature of psoriasis is Scaling.
  • 10% of cases of psoriasis are associated with arthritis.
  • Worsening of psoriasis is seen during winter.
  • In psoriasis,no scaly, red lesions are seen in inframammary and natal area.
  • Abscess may be seen in Psoriasis.
  • Least common site involvemnet in psoriasis is CNS involvement.
  • Psoriasis is exacerbated by- Lithium , B- blockers , Antimalarials,Metformin,Interferon-Alpha.
  • Treatment of Psoriasis includes PUVA and Methotrexate.
  • Treatment of pustular psoriasis is Retinoids.
  • A patient with psoriasis was started on systemic steroids. After stoping the treatment, patient developed universally red scaly skin with plaques losing their margins all over his body. The most likely cause is Erythrodermic Psoriasis.
  • A patient with psoriasis was started on systemic steroids. After stopping treatment, the patient developed generalized pustules all over the body. The cause is most likely to be Pustular Psoriasis.
  • The only indication of giving corticosteroids in pustular psoriasis is Psoriatic Erythroderma with pregnancy.
  • DOC for a pregnant woman in 2" trimester with pustular psoriasis is Prednisolone.
  • Only definitive indication of systemic steroids in psoriasis is Impetigo Herpetiformis.
  • Photosensitive Dermatitis are Psoriasis, Pellagra, Pemphigus, SLE, Congenital erythropoietic porphyria.
  • Diathronol ointment is used for Psoriasis.
  • Silver plaques are a feature of Psoriasis.
  • Koebner's phenomenon seen in Psoriasis.
  • Thimble pitting of nails is seen in Psoriasis.
  • Vitamin D analogue calcitriol is useful in the treatment of Psoriasis.
  • Grattage test is used for Psoriasis.
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