Psoriasis

• Chronic, inflammatory, multisystem disease with predominantly skin and joint manifestations'. It is characterized by scaly skin lesions, which can be in the form of patches, papules, or plaques. Itch is often a feature. The skin lesions of psoriasis are characterized by hyperproliferation of the epidermis, dilatation and proliferation of blood vessels in the dermis, accumulation of inflammatory cells, particularly neutrophils and T-lymphocytes. When the number of neutrophils in the stratum corneum (present in all forms of psoriasis) is sufficient to be clinically obvious, the condition is termed 'pustular psoriasis'. Chronic plaque psoriasis (including scalp psoriasis, flexural psoriasis, and facial psoriasis) is the most common form, affecting 80–90% of people with psoriasis. The second most common form is localized pustular psoriasis of the palms and soles. Other forms include nail psoriasis, guttate psoriasis, erythrodermic psoriasis, generalized pustular psoriasis

• Chronic plaque psoriasis: Emollients, potent topical corticosteroids + Vitamin D analogue for 4 weeks (one in am, one in pm), Vitamin D analogue (if control not satisfactory). If not better after 4-6 weeks repeat corticosteroids BD or coal tar preparation. Consider dithranol. Referral if severe or extensive (>10% body area) to consider phototherapy, systemic non-biological therapy e.g. methotrexate, biological therapy e.g. anti-TNF

• Face, flexor and genitals: Mild/moderate potent topical corticosteroids max 2 weeks. Refer dermatology to consider topical calcineurin inhibitor

• Guttate psoriasis: characterised by multiple small 'tear drop' lesions that tend to affect most of the body. Rash comes on very quickly and may follow a streptococcal infection of the throat. Tends to affect children and young adults and has a good chance of spontaneously clearing. Management options: Mild cases: emollients may be sufficient until spontaneous clearance occurs, usually after two to three months. While natural sunlight in moderation can improve guttate psoriasis, the use of sun-beds is discouraged. Topical treatment - coal tar lotion or Alphosyl-HC cream can be beneficial as they can be applied more generally to a large area of skin. Vitamin D analogues can be used but because these treatments are best applied directly to the lesions, with large numbers of lesions application is very time consuming and may not be acceptable to some patients. Referral to dermatology for phototherapy if widespread / unresponsive

• Pustular psoriasis. Classical psoriatic lesions can be treated with a vitamin D analogue or dithranol. In palm and sole psoriasis, both hyperkeratosis and inflammation are usually present and may require separate treatments: Hyperkeratosis usually needs to be treated with a keratolytic agent such as 2% salicylic acid ointment BP. This can be alternated morning and evening with a topical steroid (usually potent, due to the thick skin at this site)

• Palmoplantar pustolosis: Thought to be distinct condition from pustular psoriasis. Erythema, yellow pustules on palms and soles fading to brown macules. Mainly presents aged >50, F>M, associated with smoking. Management options: Effective treatment can be difficult: Potent topical steroids (e.g. Betnovate or Dermovate) - occlusion with clingfilm may be of benefit. Patients failing to respond should be referred to dermatology out-patients for consideration of phototherapy or systemic therapy.

• Scalp psoriasis: Tar-based shampoo is first-line treatment for scalp psoriasis. Potent topical corticosteroids up to 4 weeks. To remove scale: Emollient cream, ointment, or oil to soften; Other scalp preparations with salicyclic acid and coal tar e.g. Cocois, Sebco; Keratolytic e.g. salicylic acid to allow other treatments to work. Scalp preparations containing a potent corticosteroid or a vitamin D analogue, either alone or in combination, can also be helpful

• Psoriasis treatments: More specific topical treatment for chronic stable plaque psoriasis on extensor surfaces of trunk and limbs involves the use of vitamin D analogues, coal tar, dithranol, and the retinoid tazarotene. However, they can irritate the skin and they are not suitable for the more inflammatory forms of psoriasis; their use should be suspended during an inflammatory phase of psoriasis. The efficacy and the irritancy of each substance varies between patients. If a substance irritates significantly, it should be stopped or the concentration reduced; if it is tolerated, its effects should be assessed after 4 to 6 weeks and treatment continued if it is effective

• Vitamin D and analogues: First-line for the long-term treatment of plaque psoriasis; they do not smell or stain and they may be more acceptable than tar or dithranol products (Tacalcitol and calcitriol less likely to irritate): Calcipotriol ointment (non-proprietary or Dovonex); + betamethasone (Dovobet); Tacalcitol; Calcitriol

• Tazarotene: Retinoid with similar efficacy to vitamin D and its analogues, but associated with a greater incidence of irritation. Although irritation is common, it is minimised by applying tazarotene sparingly to the plaques and avoiding normal skin; application to the face and in flexures should also be avoided. Tazarotene does not stain and is odourless

• Dithranol: effective for chronic plaque psoriasis. Major disadvantages are irritation (for which individual susceptibility varies) and staining of skin and of clothing. Should be applied to chronic extensor plaques only, carefully avoiding normal skin. Not generally suitable for widespread small lesions nor should it be used in the flexures or on the face. Treatment should be started with a low concentration such as dithranol 0.1%, and the strength increased gradually every few days up to 3%, according to tolerance

• Coal tar: Has anti-inflammatory and antiscaling properties. Crude coal tar (coal tar, BP) is the most effective form, typically in a concentration of 1 to 10% in a soft paraffin base, but few outpatients tolerate the smell and mess. Cleaner extracts of coal tar included in proprietary preparations, are more practicable for home use but they are less effective and improvement takes longer. Contact of coal tar products with normal skin is not normally harmful and they can be used for widespread small lesions; however, irritation, contact allergy, and sterile folliculitis can occur. Milder tar extracts can be used on the face and flexures. Tar baths and tar shampoos are also helpful

• Phototherapy: available in specialist centres. Ultraviolet B (UVB) radiation is usually effective for chronic stable psoriasis and for guttate psoriasis. Consider for patients with moderately severe psoriasis in whom topical treatment has failed. Photochemotherapy combining long-wave ultraviolet A radiation with a psoralen (PUVA) is effective in most forms of psoriasis. Adverse effects include phototoxicity, pruritus, skin ageing, increase the risk of dysplastic and neoplastic skin lesions, especially squamous cancer, and pose a theoretical risk of cataracts.

• Systemic treatment psoriasis that affects the scalpunder specialist supervision e.g. acitretin, ciclosporin and methotrexate

• Emollients: in addition to symptomatic relief, may have an antiproliferative effect, and may be the only treatment necessary for mild psoriasis. Emollients are useful adjuncts to other more specific treatment

• Topical corticosteroids: Not generally suitable for long-term use or as the sole treatment of extensive chronic plaque psoriasis; any early improvement is not usually maintained and there is a risk of the condition deteriorating or of precipitating an unstable form of psoriasis (e.g. erythrodermic psoriasis or generalised pustular psoriasis) on withdrawal. Short-term use may be appropriate to treat psoriasis in specific sites such as the face or flexures (with a mild or moderate corticosteroid), and psoriasis of the scalp, palms, and soles (with a potent corticosteroid). Very potent corticosteroids should only be used under specialist supervision. Eczema co-existing with psoriasis may be treated with a corticosteroid, or coal tar, or both

• Resources: ​Psoriasis (CKS), Psoriasis: an overview and chronic plaque psoriasis (PCDS), Topical preparations for psoriasis (BNF), Psoriasis of the hands and feet including palmoplantar pustulosis (patient.info)

Ichthyosis

• Ichthyosis (PCDS)

Lichen planus / sclerosis / simplex

• Lichen planus (PCDS), Lichen sclerosis - syn. lichen sclerosus et atrophicus (PCDS), Lichen simplex - syn. circumscribed neurodermatitis (PCDS)

​Necrobiosis lipoidica

• Necrobiosis lipoidica (PCDS)

Pityriasis rosea

• May be associated with viral infections but not thought to be contagious. Young people aged 10-35. Can be itchy. Maybe associated with mild viral symptoms. Herald patch (larger with demarcated border) precedes main rash by a few days. Rash predominantly affects trunk but can involve limbs and rash. Distribution of lesions on trunk can give Christmas tree-like appearance. Oval dull-pink macules which can have fine scale. Differential includes secondary syphilis (usually also affects palms/soles). Usually self-limiting within 6-12 weeks. Use emollient, calamine or mild topical steroid if rash is itchy. Pityriasis rosea (PCDS), Pityriasis rosea (CKS)​, Pityriasis rosea (patient.info)