Lesions are well demarcated, salmon pink in colour and are surmounted by silvery scaling that may be exaggerated by lightly traumatizing the skin with the edge of a finger-nail.
The majority of patients with a plaque type of psoriasis show involvement of the skin over the extensor surfaces of the limbs such as the elbows and knees, with scattered smaller lesions on the limbs and trunk that increase with exacerbation of the disease. Involvement of the scalp with thickened hyperkeratotic scale is common. This is most clearly seen at the hair margin or over the occiput. The arthropathy associated with psoriasis.
This is a less common type of psoriasis that may be seen together with plaques or may occur alone. Lesions have a pinkish glazed appearance, are clearly demarcated and non-scaly. The groin, perianal and genital skin are principally involved. Other sites include inframammary folds and the umbilicus. The condition may prove intractable in situations such as the inframammary fold of elderly women with large and pendulous breasts, or when associated with incontinence.
This may occur in various patterns and in children it is often an isolated finding involving a single digit. The nail dystrophy most commonly seen is yellow discoloration and thickening. Scaling may be pronounced over the digit and, in association with erythema, may spread over the finger.
In its most common form, pustular psoriasis affects the alms or soles with areas of well-demarcated scaling and erythema (Fig. 2004). The pustules, which are sterile, may appear white, yellow or greenish in colour and when dried are deep brown. Pustulation may not always be vident and it is often associated with increased disease activity. When the condition is grossly hyperkeratotic and occurs in a conical or papular form it is termed rupioid; identical lesions are seen as one of the cutaneous features of Reiter’s syndrome (keratoderma blennorrhagica).
The trunk and limbs may be involved by an almost universal scaling as exfoliative or erythrodermic psoriasis. When this condition is seen in association with superficial pustule formation it is termed generalized pustular psoriasis. This is a serious life-threatening condition, similar to having widespread burns. Such a disease may occur spontaneously but it is seen more frequently after the use of potent corticosteroid therapy given orally or by topical application.
This can occur in isolation with no evidence of psoriasiselsewhere. The changes most commonly seen include pitting and onycholysis, when separation of the distal edge of the nail from the underlying vascular bed produces a whitish appearance. A red/brown, salmon-pink or ‘oilstain’ coloration may be seen under the nail proximal to the onycholysis. Less commonly the nails are ridged or furrowed. Hyperkeratosis beneath the nail is a pattern of the disease most often seen on the toe-nails, especially in association with pustular variants of psoriasis. When only one or two toe-nails are affected it may be difficult to distinguish from a fungal infection.
The majority of patients can cope with the chronic nature of the disease but the physician must take an active role in treating exacerbations. Tolerance and understanding are required in helping patients to overcome the social stigma that may be associated with their disease. Intensive treatment with topical agents can be messy and may need to be carried out in day-care centres or in hospital.
Dithranol (inhibits DNA synthesis) in concentrations of between 0.05 and 0.5% in zinc and salicylic acid paste (Lassar’s paste) is applied to the lesional skin and the normal skin is protected by wearing a tubular stockingette suit. Repeated daily treatments are necessary. The applicationc of this paste is preceded by a tar bath and minimal erythema doses of UVB (UV light of short wavelength). The intensity of the UV irradiation is gradually increased throughout the treatment period. Coal tar and salicylic acid ointment sometimes containing dithranol in concentrations of between 0.05 and 0.1% is applied overnight to the scalp and removed in the morning with a tar-containing shampoo. Coal tar is often used as an alternative to dithranol in the USA. Outpatient treatments
DITHRANOL is applied at increasing concentrations of between 1 and 3% mixed with 5% salicylic acid in white soft paraffin for up to 20 minutes’ therapy and is then washed off. Irritancy and staining of the skin can prevent regular use.
COMBINED PREPARATIONS of corticosteroids with dithranol or an alcoholic solution of coal tar are especially valuable at low concentrations in the treatment of flexural psoriasis, or for patients with widespread lesions who experience irritation with dithranol applied in a paste form. They are cosmetically acceptable or use in the horne.
TOPICAL STEROIDS can be used but long-term usage of potent steroids should be avoided. CALCIPOTRIOL (topical vitamin D3) is useful for limited and mild psoriasis. It is simple to apply, clean and therefore, acceptable to the patient. LOW-DOSE TETRACYCLINE in prolonged courses may be helpful in unremitting pustular psoriasis on thealms and soles. This treatment tends to limit the accumulation of polymorphonuclear leucocytes, a prominent feature in the pathology of the disease. RETINOIC ACID DERIVATIVES, e.g. acitretin, taken by mouth (1 mg kg:’ daily), are helpful in managing pustularand other forms of psoriasis. However, long-term treatment may be required and this can cause loss of hair, dryness of the skin, hepatic disturbance, hyperlipidaemia and hyperostoses. As it is teratogenic it should not be given to women of childbearing age. PSORALENS WITH UVA (PUVA) THERAPY may improve or clear most patterns of psoriasis. Photosensitizing agents, e.g. psoralens, are taken orally 2 hours before or applied topically 30 min before exposure to UVA. Exposure for 2-15 min on two to three occasions each week usually results in clearance of the psoriasis in 10-12 weeks. Maintenance treatment is requiredevery 2-3 weeks in most patients to keep the skin clear.
NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDs). Troublesome joint disease may respond to these drugs. CYTOTOXIC DRUGS may help alleviate widespread intractable cutaneous disease and painful joints in older patients. Patients with severe chronic psoriasis may experience complete and long-term rerrussion with methotrexate in doses of up to 30 mg once a week. Apart from bone marrow suppression, cumulative dosage of this drug can lead to hepatic fibrosis. Liver biopsies are required before starting the drug and at yearly intervals, as routine blood tests cannot detect the liver fibrosis. The fibrotic changes tend to be nonprogressive, if the drug is stopped. Hydroxyurea can be used and is not hepatotoxic. Azathioprine is more effective on the arthropathy. Cyclosporin by mouth is successful in treating psoriasis, but serious side-effects will limit long-term use.
SELF-HELP GROUPS provide support for patients. SEBORRHOEIC DERMATITIS
• Seborrhoeic dermatitis affects those areas of the skin where there is a high density of sebaceous glands. The cause is unknown and no consistent alteration in the function of the sebaceous glands has been demonstrated. For many years observers have attempted to link the disease to lipophilic yeasts that are present on the normal skin as saprophytes, e.g. Pityrosporum orbiculare and P. ovale, which occur on the trunk and scalp respectively. Bacterial infection has also been considered in the pathogenesis but infection is probably secondary to the skin maceration. eurogenic factors playa role in that patients with Parkinson’s disease may develop similar clinical features over their facial skin and continuing mental stress often exacerbates the disease. Patients are often fairskinned types of Celtic origin and so genetic factors may also be relevant.
The prevalence of this condition in AIDS is approximately 80% (see p. 99). It is often the presenting cutaneous feature of the disease and is correlated with a poor prognosis.
The scalp is principally involved and shows diffuse scaling and erythema. Papules and pustules may accompany these changes or present as the only manifestation of the disease. The spread locally is to the eyebrows, nasolabial folds, the ears and neck. Blepharitis and otitis externa canoccur as single features, or they may accompany more wid espread disease. Other skin sites affected include the sternal region, the thoracic spine and the paraspinal skin, the axillae, the groin folds and the perianal region. Greasy scales, weeping and maceration are seen with more severe or acute disease. A folliculitis may be the predominant feature on the trunk.
On occasions the condition may be seen together with more typical eczematous changes elsewhere on the skin; the term seborrhoeic eczema is often used to describe this pattern.
Shampoos that contain substances that have a fungostatic action, e.g. selenium sulphide, zinc pyrithione or econazole, can give initial benefit to patients with a scaly and greasy scalp. It is a good principle to change the shampoo after 6-8 weeks. These shampoos tend to aggravate the scalp if there are marked inflammatory lesions and antiseptic preparations such as cetrimide or povidone-iodine in shampoo forms can be added. Ketoconazole shampoo used every 10-14 days long term will often control scalp symptoms; more frequent use on the trunk or facial skin may control disease at these sites.
A course of tetracycline (250 mg twice daily), minocycline or doxycycline given for 2-3 months may lower the intensity of the inflammatory patterns of the disease. Itraconazole also reduces inflammation. Lotions, creams or antiseptic powders may help to diminish maceration of the skin involving body folds. Steroid creams should be those of relatively low potency, and preferably they should be combined with an antibiotic or antiseptic such as tetracycline or clioquinol.Candidiasis may accompany chronic disease and imidazole/hydrocortisone combination creams often help this and other features of the disease.