Chapter 5 Psoriasis

Psoriasis Chronic, non-infectious, immuno-inflammatory skin disorder Well-defined Salmonpink plaques bearing large adherent silvery centrally attached scales. Cause (unknown) Genetic predisposition Environmental trigger There are 2 key abnormalities in a psoriatic plaque: Hyperproliferation of keratinocytes Inflammatory cell infiltrate (neutrophils, TNF & Th17)

Epidermal cell kinetics Genetics 2 inheritance modes Onset in youth and a more common family history of psoriasis Onset in late adulthood in patients without obvious family history. Polygenic inheritance. 16% :A child with one affected parent 50%: if both parents are affected. If non-psoriatic parents have a child with psoriasis, the risk for subsequent children is about 10%. 70% of monozygotic twins 20% of dizygotic ones. Epidermal cell kinetics The growth fraction of epidermal basal cells is greatly increased to almost 100% compared with 30% in normal skin. The epidermal turnover time is greatly shortened, to less than 10 days compared with 30 to 60 days in normal skin.

Precipitating factors Trauma (Köbner phenomenon) skin damaged by scratches or surgical wounds Infection Tonsillitis caused by β-haemolytic streptococci (guttate psoriasis). Staphylococcus aureus HIV infection Hormonal Psoriasis frequently improves in pregnancy Only to relapse postpartum. Sunlight Improves most psoriatics but 10% become worse. Drugs Antimalarials, beta-blockers, IFN-α and lithium may worsen psoriasis Cigarette smoking and alcohol Emotion

Fig. 5.1 The Köbner phenomenon seen after a recent thoracotomy operation.

Histology (Fig. 5.2) The main changes are the following. Parakeratosis (nuclei retained in the horny layer). Irregular thickening of the epidermis over the rete ridges, but thinning over dermal papillae. Bleeding may occur when scale is scratched off (Auspitz’s sign). Epidermal polymorphonuclear leucocyte infiltrates and Munro micro-abscesses. Dilated and tortuous capillary loops in the dermal papillae. T-lymphocyte infiltrate in upper dermis. No granular layer

Presentations Plaque pattern Guttate pattern Scalp Nails Flexures (not scaly) Palms and soles (painfull) Napkin psoriasis Acute generalized pustular psoriasis Rare, but serious Fever Recurrent Erythrodermic psoriasis Fig. 5.3 Psoriasis: extensive plaque psoriasis.

Symmetrical sites on the: Elbows, knees Lower back Scalp Plaque pattern Most common type. Well demarcated Pink or red with large, centrally adherent, silvery white, polygonal scales. Symmetrical sites on the: Elbows, knees Lower back Scalp Fig. 5.4 Psoriasis favours the extensor aspects of the knees and elbows.

Guttate pattern The word ‘guttate’ means ‘drop-shaped’. Usually seen in children and adolescents may be the 1st sign Triggered by streptococcal tonsillitis. Numerous small round red macules come up suddenly on the trunk and soon become Scaly The rash often clears in a few months Plaque psoriasis may develop later. DDx: Pityriasis rosea Fig. 5.5 Guttate psoriasis.

Fig. 5.7 Thimble-like pitting of nails with onycholysis. Fig. 5.8 Onycholysis. Thimble pitting Onycholysis (separation of the nail from the nail bed) Sometimes subungual hyperkeratosis.

Fig. 5.9 Sharply defined glistening erythematous patches of flexural psoriasis. Most common in women, elderly & HIV infected individual. Psoriasis of the submammary, axillary and anogenital folds. Not scaly Glistening sharply demarcated Red plaques Often with fissuring in the depth of the fold May harbour psoriasis in their gluteal fold. Fig. 5.6 Untreated severe and extensive scalp psoriasis. Not affect the hair

Fig. 5.11 A closer view of pustules on the sole. Palms and soles Hard to recognize Often poorly demarcated Barely erythematous. May develop painful fissures Pustulosis Followed by brown macules or scales. Painful May be disabling. Fig. 5.10 Pustular psoriasis of the sole.

Fig. 5.13 Erythrodermic psoriasis. Rare Trigerrd by irritant effect of tar, dithranol, drug eruption or withdrawal of potent topical or systemic steroids. The skin becomes universally and uniformly red with variable scaling. Malaise, shivering, hot skin & uncomfortable. Fig. 5.12 An irritant napkin rash now turning into napkin psoriasis.

Complications Psoriatic arthropathy Post inflammatory pegmintation (mostly hypo) Erythrodermic psoriasis Fig. 5.15 Rheumatoid-like changes associated with severe psoriasis of hands. Fig. 5.14 Fixed flexion deformity of distal interphalangeal joints following arthropathy.

DDx: Discoid eczema Seborrhoeic eczema Pityriasis rosea Secondary syphilis Cutaneous T-cell lymphoma Tinea unguium Investigations Biopsy is seldom necessary. Throat swabbing for β-haemolytic streptococci is needed in guttate psoriasis. Skin scrapings and nail clippings may be required to exclude tinea. Radiology and tests for rheumatoid factor are helpful in assessing arthritis.

Treatment Topical Vitamin D analogues (Calcipotriol ) Systemic Local retinoids (Tazarotene) Topical corticosteroids Dithranol (anthralin) Coal tar preparations Salicylic acid Calcineurin inhibitors (topical immunomodulators) Ultraviolet radiation Systemic Photochemotherapy (PUVA) Retinoids (Acitretin) Methotrexate Ciclosporin Antimetabolites Biological agents Combined

Fig. 5.16 Unstable psoriasis following long-term use of a potent topical steroid. Fig. 5.17 Ultraviolet radiation therapy.

Fig. 5.18 Therapeutic targets of the major biological agents used in psoriasis. Etanercept is a soluble receptor for TNF-α Infliximab and adalimumab are antibodies to TNF-α. MHC, major histocompatibility complex; TCR, T-cell receptor; TNF, tumour necrosis factor.

Effect S/E Vitamin D analogues Reducing epidermal proliferation Restoring a normal horny layer. Inhibit polyamines synthesis Transient irritation Local retinoids Reduce keratinocyte proliferation Irritation Topical corticosteroids Clean & reduce scaling & redness Dermal atrophy Tachyphylaxis Early relapses Precipitation of unstable Psoriasis Adrnal suppression (rare) Dithranol Inhibit DNA synthesis Purple–brown discoloration Coal tar preparations Photosensitizes the skin Reputation as a carcinogen UV radiation Short term: Acute phototoxicity Long term: Photodamage Skin cancer

Cutaneous malignancies PUVA Inhibits DNA synthesis & epidermal cell Division Painful erythema Itch Nauseated Long-term side-effects: Premature ageing of the skin Cutaneous malignancies Cataract formation Retinoids Dry lips, mouth, vagina and eyes Teratogenic Heart disease (hyperlipidaemias) Hair thinning or loss Methotrexate Inhibits proliferating lymphoid cells Hepatic fibrosis Nausea and malaise Oligospermia Ciclosporin inhibits cell-mediated immune reactions HTN Kidney damage Persistent viral warts Risk of skin cancer

Other papulosquamous disorders Pityriasis rosea Lichen planus Chapter 6 Other papulosquamous disorders Pityriasis rosea Lichen planus

Pityriasis rosea Cause: (unkown) Reactivation of HHV 7 or HHV 6. Drugs: Gold Captopril Barbiturates Penicillamine May occur in clusters Both geographical and temporal Not contagious Presentation Common during the winter. Affects children & young adults Most patients develop one plaque (herald /mother plaque) before the others After several days many smaller plaques appear Mainly on the trunk, but some also on the neck and extremities Itching (50%)

Course: Subsequent lesions enlarge over the 1st week May aching and tiredness. The eruption lasts 2–10 weeks and then resolves spontaneously Sometimes leaving hyperpigmented patches that fade more slowly. DDx: Tinea corporis Guttate psoriasis Secondary syphilis Investigations Serology for syphilis Treatment No treatment is curative Potent topical steroid or calamine lotion (itching) Salicylic acid in soft white paraffin or emulsifying ointment (reduces scaling). Sunlight or artificial UVB (relieves pruritus).

Fig. 6.1 The herald plaque usually on the trunk Larger than the other lesions. Its annular configuration. Fig. 6.2 Extensive pityriasis rosea showing a ‘fir tree’ distribution on the back.

Collarette scale (ring-like) Peripheral scale Peripherally attached Centrally dettached

Lichen planus Not infectious 5 P’s: well-defined pruritic, planar, purple, polygonal papules Cause Unknown, but the disease seems to be mediated immunologically (CD8+ cytotoxic T cells recognize Ag with MHC class I). Associated with autoimmune disorders, such as Alopecia areata Vitiligo Ulcerative colitis Gold and other heavy metals Drugs: Antimalarials, Beta-blockers, NSAIDs, Para-aminobenzoic acid, Thiazide diuretics & Penicillamine Contact with chemicals Contact allergy to mercury compounds (oral lichen planus) Some patients with lichen planus also have a hepatitis C infection

Planar Polyangular Purple papules With lacy, reticular, criss-crossed whitish lines (Wickham's striae) on the surface

Wickham's striae Primary lesion Flat-topped papule Irregular, angulated border (polygonal papules) Wickham's striae

Fig. 6.7 Histology of lichen planus.

Presentation Violaceous or lilac-coloured Intensely itchy Flat-topped papules Arise on the Extremities (volar aspects of the wrists and legs) Mouth white asymptomatic lacy lines, dots, and occasionally small white plaques Nails (10% ) changes ranging from fine longitudinal grooves to destruction of the entire nail fold and bed. Scalp lesions can cause a patchy scarring alopecia. Genitalia (male) Wickham’s striae: white streaky pattern on the surface of papules. Köbner phenomenon may occur (as psoriasis)

Fig. 6.4 Lichen planus: classic white lacy network lying on the buccal mucosa. Fig. 6.3 Shiny flat-topped papules of lichen planus. Note the Wickham’s striae. Mucous membrane lichen planus

Fig. 6.5 Lichen planus: striking Köbner effect on the forearm. Lichen planus on the penis. A lacy, white pattern Identical to that seen on buccal mucosa

Fig. 6.6 The thickened purplish lesions characteristic of hypertrophic lichen planus on the shins.

Disabling (ulceration over bony prominences, especially on the soles). Course: Individual lesions may last for many months and the eruption as a whole tends to last about 1 year. The hypertrophic variant often lasts for many years. As lesions resolve, become: Darker Flatter Leave discrete brown or grey macules. About 1/6 of patients will have a recurrence. Complications: Nail and hair loss Squamous cell carcinoma (Ulcerative form of lichen planus in the mouth). Disabling (ulceration over bony prominences, especially on the soles). Any association with liver disease may be caused by a coexisting hepatitis C infection.

DDx: Other papulosquamous diseases Oral candidiasis Generalized discoid lupus erythematosus Investigations: Obvious clinically. Biopsy (histology) Treatment: Stop drugs Potent topical steroids Systemic steroid Photochemotherapy with psoralen and ultraviolet (PUVA) or narrowband UVB (reduce pruritus and help to clear up the skin lesions). Oral ciclosporin or acitretin Antihistamines