1 diagnosis
1.1 classification
1.1.1 morphological
1.1.2 pathogenetic
1.1.3 severity
diagnosis
a diagnosis of psoriasis based on appearance of skin. skin characteristics typical psoriasis scaly, erythematous plaques, papules, or patches of skin may painful , itch. no special blood tests or diagnostic procedures needed make diagnosis.
the differential diagnosis of psoriasis includes dermatological conditions similar in appearance such discoid eczema, seborrhoeic eczema, pityriasis rosea (may confused guttate psoriasis), nail fungus (may confused nail psoriasis) or cutaneous t cell lymphoma (50% of individuals cancer misdiagnosed psoriasis). dermatologic manifestations of systemic illnesses such rash of secondary syphilis may confused psoriasis.
if clinical diagnosis uncertain, skin biopsy or scraping may performed rule out other disorders , confirm diagnosis. skin biopsy show clubbed epidermal projections interdigitate dermis on microscopy. epidermal thickening characteristic histologic finding of psoriasis lesions. stratum granulosum layer of epidermis missing or decreased in psoriatic lesions; skin cells superficial layer of skin abnormal never mature. unlike mature counterparts, these superficial cells keep nucleus. inflammatory infiltrates can typically visualized on microscopy when examining skin tissue or joint tissue affected psoriasis. epidermal skin tissue affected psoriatic inflammation has many cd8+ t cells while predominance of cd4+ t cells makes inflammatory infiltrates of dermal layer of skin , joints.
classification
morphological
psoriasis classified papulosquamous disorder , commonly subdivided different categories based on histological characteristics. variants include plaque, pustular, guttate, , flexural psoriasis. each form has dedicated icd-10 code. psoriasis can classified nonpustular , pustular types.
pathogenetic
another classification scheme considers genetic , demographic factors. type 1 has positive family history, starts before age of 40, , associated human leukocyte antigen, hla-cw6. conversely, type 2 not show family history, presents after age 40, , not associated hla-cw6. type 1 accounts 75% of persons psoriasis.
the classification of psoriasis autoimmune disease has sparked considerable debate. researchers have proposed differing descriptions of psoriasis , psoriatic arthritis; authors have classified them autoimmune diseases while others have classified them distinct autoimmune diseases , referred them immune-mediated inflammatory diseases.
severity
distribution of severity
there no consensus how classify severity of psoriasis. mild psoriasis has been defined percentage of body surface area (bsa)≤10, psoriasis area severity index (pasi) score ≤10, , dermatology life quality index (dlqi) score ≤10. moderate severe psoriasis defined same group bsa >10 or pasi score >10 , dlqi score >10. dlqi 10 question tool used measure impact of several dermatologic diseases on daily functioning. dlqi score ranges 0 (minimal impairment) 30 (maximal impairment) , calculated each answer being assigned 0–3 points higher scores indicating greater social or occupational impairment.
the psoriasis area severity index (pasi) used measurement tool psoriasis. pasi assesses severity of lesions , area affected , combines these 2 factors single score 0 (no disease) 72 (maximal disease). nevertheless, pasi can unwieldy use outside of research settings, has led attempts simplify index clinical use.
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