Papulosquamous disorders د.وسام اللامي
Pityriasis rosea
Pityriasis rosea is common, particularly during the winter, may be caused by reactivation of either human herpes virus 7 or 6. It mainly affects children and young adults, and second attacks are rare. Most patients develop one plaque ( the ‘herald’ or ‘mother’ plaque) before the others. It is larger ( 2–5 cm diameter ) than later lesions, and is rounder, redder and more scaly. After several days many smaller plaques appear, mainly on the trunk, but some also on the neck and extremities. About half of patients complain of itching. An individual plaque is oval, salmon pink and shows a delicate scaling, adherent peripherally as a collarette. The configuration of such plaques is often characteristic. Their longitudinal axes run down and out from the spine in a ‘fir tree’ pattern , along the lines of the ribs.
The herald plaque precedes the generalized eruption by several days. Subsequent lesions enlarge over the first week or two. A minority of patients have systemic symptoms such as aching and tiredness.The eruption lasts 2–10 weeks and then resolves spontaneously, sometimes leaving hyperpigmented patches that fade more slowly.
Although herald plaques are often mistaken for ringworm ( tinea corporis), the two disorders most likely to be misdiagnosed early in the general eruption are guttate psoriasis and secondary syphilis.Tinea corporis and pityriasis versicolor can be distinguished by the microscopical examination of scales, and secondary syphilis by its other features (mouth lesions, palmar lesions, condylomata lata, lymphadenopathy, alopecia) and by serology. Gold and captopril are the drugs most likely to cause a pityriasis rosea-like drug reaction, but barbiturates, penicillamine, some antibiotics can also do so.
No treatment is curative. A moderately potent topical steroid or calamine lotion will help the tching. Sunlight or UVB often relieves pruritus and may hasten resolution. Treatment with antiviral agents has not been helpful.
lichen planus
Cause is unknown, but the disease seems to be mediated immunologically. It has been postulated that cytotoxic T cells attack antigen on basal keratinocytes in lesions, and the keratinocytes are then lysed. Lichen planus is also associated with autoimmune disorders, such as alopecia areata, vitiligo and ulcerative colitis. Contact allergy to mercury compounds ( in dental amalgam fillings) seems to bean important cause of oral lichen planus, especially if there is close contact with the amalgam and If there is no concomitant cutaneous lichen planus. Drugs too can cause lichen planus. Some patients with lichen planus also have a hepatitis C infection .Typical lesions are violaceous or lilac-coloured,intensely itchy, flat-topped papules that usually arise on the extremities, particularly on the volar aspects of the wrists and legs . A close look is needed to see a white streaky pattern on the surface of these papules ( Wickham’s striae).White asymptomatic lacy lines, dots, and occasionally small white plaques, are also found in the mouth, particularly inside the cheeks, in about 50%of patients, and oral lesions may be the sole manifestation of the disease. The genital skin may be similarly affected. Curiously, although the skin plaques are usually itchy, patients rub rather than scratch, so that excoriations are uncommon. As in psoriasis, the Köbner phenomenon may occur. The nails are usually normal, but in about10% of patients show changes ranging from fine longitudinal grooves to destruction of the entire nail fold and bed. Scalp lesions can cause a patchy scarring alopecia.
Individual lesions may last for many months and the eruption as a whole tends to last about 1 year. About one in six patients will have a recurrence. Lichen planus should be differentiated from the other papulosquamous diseases. Lichenoid drug reactions can mimic lichen planus closely,like antimalarials, beta-blockers, non-steroidal anti-inflammatory drugs, para-aminobenzoic acid, thiazide diuretics and penicillamine. Contact with chemicals used to develop colour photographic film can also produce similar lesions.
The diagnosis is usually obvious clinically. The histology is characteristic so a biopsy will confirm the diagnosis if necessary. Treatment can be difficult. If drugs are suspected as the cause, they should be stopped and unrelated ones substituted. Potent topical steroids will sometimes relieve symptoms and flatten the plaques.Systemic steroid courses work too, but are recommended only in extensive involvement, nail destruction or painful and erosive oral lichen planus. Treatment with photochemotherapy with psoralen and ultraviolet A ( PUVA ) or with narrowband UVB may reduce pruritus and help to clear up the skin lesions. Oral ciclosporin or acitretin have also helped some patients with stubborn lichen planus. Antihistamines may blunt the itch. Mucous membrane lesions, both oral and genital, are usually asymptomatic and do not require treatment; if they do, then applications of a corticosteroid or calcineurin inhibitor such as tacrolimus in a gel base may be helpful.
pityriasis rubra pilaris
A group of uncommon skin disorders characterized by fine scaling ( pityriasis),redness (rubra) and involvement of hair follicles ( pilaris). No cause has been identified.. The familial type has an autosomal dominant inheritance.
The most common acquired typebegins in adult life with erythema and scaling of the face and scalp. Later, red or orange plaques grow quickly and merge, so that patients with pityriasis rubra pilaris are often erythrodermic. Perifollicularpapules and keratinous follicular plugs develop at this stage. Small islands of skin may be ‘spared’ from this general erythema. The palms and soles become thickened, smooth and yellow. The most common acquired form generally resolves within 3 years, but may recur. The familial type, developing in childhood, persists throughout life.
Emollient and keratolytics are effective for the palms and soles lesions. About 50% of patients respond slowly to systemic retinoids such as acitretin ( in adults, 25–50 mg/day for 6–8 months). Oral methotrexate in low doses, taken once a week, may also help a similar percentage. Phototherapies do not help much. Systemic steroids are not indicated.
Erythroderma
Sometimes the whole skin becomes red and scaly. ‘Erythroderma’ is the term used when the skin is red with little or no scaling, while the term ‘exfoliative dermatitis’ is preferred if scaling predominates. If the condition becomes chronic, tightness of the facial skin leadsto ectropion, scalp and body hair may be lost, and the nails become thickened and may be shed too.Temperature regulation is impaired , patient feel cold and shiver. Oedema, high output cardiac failure, tachycardia, anaemia, failure to sweat and dehydration can occur.
Some causes of erythroderma/exfoliative dermatitis
Psoriasis
Pityriasis rubra pilaris
Ichthyosiform erythroderma
Pemphigus erythematosus
Contact, atopic or seborrhoeic eczema
Drug eruptions
Crusted (Norwegian) scabies