1. Psoriasis and Other Papulosquamous Disease

2. Definitions – Psoriasis is the most common chronic papulosquamous disease – The classic lesion of psoriasis is a well-demarcated erythematous plaque with a silvery (micaceous) scale – Removal of the scale commonly results in bleeding (Auspitz sign)

3. Psoriasis is common (2% of the population) As a chronic inflammatory disease it is associated with systemic disease that might be preventable Cardiovascular disease Obesity and smoking precede the development of moderate to severe psoriasis Early, aggressive treatment might lessen the occurrence of some of the co-morbidities and improve survival

4. Epidemiology Psoriasis affects roughly 2% of the population Equal sex distribution. Onset is bimodal – Peaks between 20-30 and 50-60 years of age, but it can occur at any age from birth to death. Familial cases are not uncommon

5. Etiology/Pathogenesis Genetic basis for the disease is not fully understood Environmental trigger factors Trauma – Koebner phenomenon Stress Streptococcal infection Drugs – e.g. lithium, beta blockers, possibly antimalarial agents Pustular psoriasis has been associated with the withdrawal of corticosteroid therapy Psoriasis is a disease associated with chronic inflammation and a variety of immunologic and cytokine abnormalities are believed to be related to disease expression

6. Clinical Variants Psoriasis vulgaris Guttate psoriasis Pustular psoriasis Inverse psoriasis Erythrodermic psoriasis

7. Psoriatic arthritis Affects between 7 & 21% of patients with psoriasis May occur prior to, concurrent with or subsequent to psoriasis More common in patients with moderate to severe cutaneous disease and those with nail involvement

8. Psoriasis Vulgaris

9. Guttate Psoriasis

10. Pustular Psoriasis Localized pustular psoriasis Generalized pustular psoriasis

11. Erythrodermic Psoriasis

12. Koebner Phenomenon

13. Nail Disease in Psoriasis

14. Psoriatic Arthritis

15. Diagnosis of Psoriasis Clinical diagnosis Exclude other papulosquamous diseases and chronic eczemas When the clinical disease is typical, then the histopathological features are also characteristic, however when the disease is atypical the histopathology is often non- specific

16. Differential Diagnosis Chronic Dermatitis Seborrheic Dermatitis Pityriasis rosea Lupus erythematosus Dermatophyte infection Cutaneous T-cell lymphoma (mycosis fungoides) Lichen planus

17. Chronic Atopic Dermatitis

18. Chronic Dermatitis

19. Pityriasis Rosea

20. Secondary Syphilis

21. Cutaneous Lupus Erythematosus

22. Dermatomyositis

23. Dermatophyte Infection

24. Onychomycosis

25. Cutaneous T-cell Lymphoma