1. Chapter 5
Psoriasis

2. 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)

3. 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.

4. 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

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

6. 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

7. 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.

8. 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.

9. 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.

10. 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.

11. 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

12. 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 Pustular psoriasis of the sole.

13. 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 An irritant napkin rash now turning into napkin psoriasis.

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

15. 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.

16. 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

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

19. 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.

21. 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

22. 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

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

24. 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%)

25. 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).

26. 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.

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

28. 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

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

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

33. Fig. 6.7 Histology of lichen planus.

34. 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)

35. 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

36. 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

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

38. 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.

39. 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