- Psoriasis is thought to be a T-cell driven disease. Some have regarded psoriasis as an autoimmune disease.
- Factors/Triggers associated with psoriasis are genetics, infection (streptococcal), HIV, IFN, endocrine factor (hypocalcemia), psychogenic stress, medication (lithium, IFN, beta-blockers, anti-malarials, rapid steroid tapers), alcohol consumption, smoking, and obesity.
- Psoriasis associated with various HLA type - HLA-B13,HLA-B17, HLA-B37.
Clinical Presentation and Types:
I. Chronic Plaque Psoriasis - Relatively symmetrical distribution. Lesions are erythematous, micaceous plaques, typically involves elbows, knees, scalp, presacrum and some times the hands and the feet.
II. Guttate Psoriasis: Small red patches, often diffusely located over the body. Covering almost 50% of the body, an elevated antistreptolysin O, anti-DNase B, or streptozyme titer is found. Often seen in children after streptococcal throat infection. In adults, guttate lesions can become chronic.
III. Erythrodermic psoriasis - Diffuse erythema and scaling covering most of the body. Clues include classic location and nail changes.
IV. Pustular Variants
a.} Generalized pustular psoriasis - Erythema and pustules predominate the picture. Triggers include rapid taper of systemic steroids, pregnancy, hypocalcemia, infection etc. Four distinct patterns - von Zumbusch, annular, exanthematic and localized (within existing psoriatic plaques).
b.) Pustulosis of the palms and soles - Deep-seated, multiple, sterile pustules admixed with yellow-brown macules. Minority of the patients also have chronic plaque psoriasis lesions elsewhere. Focal infections, stress can trigger this. Smoking can aggravate the problem. This is one of the entities most commonly associated with sterile inflammatory bone lesions
c.} Acrodermatitis continue of Hallopeau - Pustules at the distal portions of the fingers and sometimes the toes. Pustulation often followed by scaling and crust formation. Pustules may also form in the nail bed (beneath the nail plate) and there may be shedding of the nail plate.
V. Inverse Psoriasis - Shiny, pink to red, sharply demarcated plaques. Much less scale seen than in other areas. Central fissuring common. Typical sites inclde axillae, inguinal creases, intergluteal cleft, inframammary region, and retroauricular folds.
VI. Nail Psoriasis - Reported in 10-80% of psoriatic patients. Fingernails are greater than toe nails. Findings include oil spots distal onycholysis, splinter hermorrhages, subungual hyperkeratosis and leukonychia.
Disorders related to psoriasis skin disease:
- Inflammatory linear verrucous epidermal nevus (ILVEN)
- Reactive arthritis.
- Confluent parakeratosis, hyperkeratosis
- Neutrophils in stratum corneum (Munro micro abscesses) and in spinous layer (spongiform pustules of Kogoj)
- Hypogranulosis and suprapapillary thinning of epidermis
- Regular acanthosis, often with clubbed rete ridges
- Dilated capillaries in dermal papillae (cause of Auspitz sign)
- Perivascular lymphocytes
TREATMENT: After complete investigation, vitamin D3 analogues, topical retinoids, topical PUVA, NB UVB, salcylic acid analogues, oral immunosuppressants and biologics are the different treatment options.
Pearls and pitfalls:
- Patients with psoriasis have an increased risk of cardiac disease
- Many Patients have fatty liver prior to staring medication, but it can complicate the treatment.
- Encourage cessation of smoking as this may aggravate psoriasis. Additionally, these patients already have an increased risk of heart disease and stroke.
- Crohn' s disease, ulcerative colitis, and psoriasis share an important association with sacroilitis, and HLA-B27 positivity.
- Always screen for joint pain, psoriatic arthritis. This may significantly change the management of disease.