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Scaly skin diseases

Psoriasis key points test

A family history of psoriasis is found in: * Three-quarters of patients * About half of patients *! A third of patients * Ten percent of patients Explanation: Psoriasis has a strong genetic basis with HLA associations and about a third of patients have an affected relative. Many families appear to exhibit autosomal dominant patterns of inheritance with decreased penetrance. Cytokines important in the pathogenesis of psoriasis include: # Th2 pattern #! Th1 pattern #! Tumour necrosis factor alpha # Interleukin 4 and 5 Explanation: Psoriasis is an inflammatory skin condition characterized by abnormal epidermal differentiation and hyperproliferation initiated and maintained primarily by T cells in the dermis producing cytokines. The Th1 cytokines include tumour necrosis factor alpha, interleukin-2 and -12 and gamma interferon. Choose the best diagnosis: Mix and match [table] : Chronic plaque psoriasis || Chronic plaque psoriasis is the commonest presentation with few or many scaly plaques at least several centimeters in diameter, often favouring extensor aspects of the elbows and knees. : Guttate psoriasis || Guttate psoriasis presents with numerous small plaques predominantly on the trunk and is often precipitated by haemolytic streptococcal infection. : Inverse psoriasis || "Inverse psoriasis" is the name given for psoriasis confined to the flexures (in and behind ears, axillae, submammary, umbilical, inguinal, genital). : Chronic plaque psoriasis || Chronic plaque psoriasis is the commonest presentation with few or many scaly plaques at least several centimeters in diameter, often favouring extensor aspects of the elbows and knees. : Guttate psoriasis || Guttate psoriasis presents with numerous small plaques predominantly on the trunk and is often precipitated by haemolytic streptococcal infection. : Chronic plaque psoriasis || Chronic plaque psoriasis is the commonest presentation with few or many scaly plaques at least several centimeters in diameter, often favouring extensor aspects of the elbows and knees. Choose the best description: Mix and match [table] : Onycholysis || There are many causes of onycholysis (separation of nail plate from nail bed). Psoriatic onycholysis is often irregular, tender and characterized by a red-yellow inflammatory band proximal to the nail separation. : Total nail dystrophy || Total nail dystrophy takes various forms in psoriasis and may be difficult to distinguish from severe onychomycosis. Clippings should be cultured for mycology; fungal infection may coexist with psoriasis. : Subungual hyperkeratosis || Thickened skin under the distal nail plate (hyponychium) is characteristic of psoriatic onycholysis but may also arise with fungal infection and idiopathic nail dystrophies. Choose the best diagnosis: Mix and match [table] : Exanthematic psoriasis || A sudden flare of large areas of erythema in a patient with pre-existing psoriasis may be due to or resemble a viral exanthem. This may lead to erythroderma. : Palmoplantar pustulosis || Groups of sterile pustules are found on the instep and heels or the centre of the palm and thenar eminence. Although often unilateral, palmoplantar pustular psoriasis eventually affects both palms and /or soles. It may be seen alone (palmoplantar pustulosis) or in association with chronic plaque psoriasis. : Generalised pustular psoriasis || Generalised pustular psoriasis is a serious disease, which frequently starts abruptly in a patient who may or may not have had stable plaque psoriasis previously. The edges of the plaques are studded with tiny subcorneal pustules which readily break to form circinate scaling. The patient is frequently unwell with fever, hypocalcaemia and other signs of metabolic upset. : Chronic plaque psoriasis || This form of psoriasis is characterized by well demarcated, indurated, erythematous plaques that are covered with loose flakes of white scale.