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Psoriasis

common papulo-squamatous disorder, mostly over extensor surface, associated with HLA-B27, infection, drugs(lithium) shows parakeratosis, acanthosis, suprapapillary thining, with inflammatory infiltrates, featured with koebners phenomenon, auspitz sign, wornoff's ring, oil drop sign in nail, treated with topical corticosteroids, coal tar, calcipotriol, systemic steroids, methotrexate, acitretin, cyclosporine.

Dermatology Psoriasis #psoriasis #rashes #pruritis #itching rash

'Psoriasis is chronic, T-cell mediated papulo-squamatous disease that affect mostly extensor surface, characterized by well demarcated red, scaly patches. Skin is inflamed and hyperproliferates to about 10 times normal rate.

Etiology:

Polygenic : HLA-B27 (* remeber ankylosing spondilitis, ulcerative colitis, RA)
environmental factors: seasonal exacerbation usually on winter
Infections: HIV, Streptococcal(cause guttate psoriasis)
Drugs: lithium
UV lights
Alcohol, stress

Histopathology:

Parakeratosis: retain nuclei in Stratum corneum
Hyperkeratosis: thickening of St. corneum
Munro microabscess: Neutrophils in St. corneum
Absent St. granulosum
Spongiform pustules of Kogoj: Neutrophil in St. spinosum
Supra-papillary thining
Acanthosis, Agranulosis
T-cell infiltration

Variants:

Morphological variant: Guttate and Rupioid
Modification by site
Flexural psoriasis
Scalp psoriasis
Nail psoriasis
Penile psoriasis
Psoriasis of palms and soles

Clinical Vairants:

Chronic plaque psoriasis: aka psoriasis vulgaris, silvery white scales over extensor surface
Pustular psoriasis: Sterile pustules with inflammatory cells, triggered by systemic steroids, sheets of pus like features
Erythodermic psoriasis: looks like exfoliative dermatitis , shows erythema with or without scaling

Clinical Features:

Symptoms:

raised scaly rashes
itching
worse in winter
dry and rough skin

Signs:

erythematous scaly papules/plaque, silvery scale
pruritis
subungal debris, brownish black discoloration ( oil drop sign) - nail
thimble pitting nail (onycholysis)
koebner's phenomenon (isomorphic phenomenon): appears at site of injury such as scratch
Grattage test: sliding glass slide accentuate scaling
Auspitz sign: pin point bleeding on doing more grattage sign
Wornoff's ring: hypopigmented ring around lesion of psoriasis

Investigation:

it's usually not needed.

Treatment:

General measures:
- counseling of patient
- reassurance and emotional support
- inform about disease and its process, prognosis and relapse
- encourage physical exercise and mental rest
Specific measures:
- Topical agents: (recommende for <10% BSA)
  - Emoliants: decreases scaling
  - Steroids: Clobetasol(0.05%)
  - Coal tar: antiproliferative action
  - Dithranol
  - Calcipotriol
- Systemic:
  - Methotrexate
  - Cyclosporine
  - Retinoids
  - Vit. A analogues
  - oral Antibiotics
  - Other biological: Etanercept. Infliximab, Efalizumab
- PUVA & UVB therapy (for >10% BSA)
  - PUVA - 300-400 nm (photosensitized with psoralen)
  - PUVA-SOL
  - UVB: narrow band UV B 311+-2 without psoralen
- Combination therapy can be given