psoriasis

Question 1

definition of psoriasis

Answer 1

chronic inflammatory skin disease with characteristic lesions and may be complicated by arthritis

characteristic lesions - erythematous, circumscribed scaly papules and plaques

Question 2

aetiology of psoriasis

Answer 2

unknown

genetic, env and drugs

eg may be triggered by streptococcal infections, antimalarial agents, B blockers, lithium

Question 3

associations/RF for psoriasis

Answer 3

guttate psoriasis - streptococci sore throat

palmoplantar pustulosis - smoking, middle aged women, autoimmune thyroid disease, SAPHO (synovitis, acne, palmoplantar pustulosis, hyperostosis seen on radiographs, osteitis - chronic recurrent multifocal inflammation of bones eg sternoclavicular, sacroiliac joint)

generalised pustular - hypoparathyroidism

Question 4

epidemiology of psoriasis

Answer 4

1-2% of population

peak onset 20yrs

Question 5

symptoms of psoriasis

Answer 5

itching or occaisionally tender skin

irritation, burning and stinging

pinpoint bleeding with removing scales (Auspitz phenomenon)

skin lesions may develop at sites of trauma/scars (Koebner phenomenon

red, inflamed, silvery-white scaly, and circumscribed papules and plaques

look in scalp

Question 6

signs of discoid/nummular psoriasis

Answer 6

symettrical well-demarcated erythematous plaques with silvery scales over extensor surface

knee, elbow, scalp, sacrum

Question 7

signs of flexural psoriasis

Answer 7

less scaly paques

in axilla, groins, perianal and genital skin

Question 8

signs of guttate psoriasis

Answer 8

small 1cm drop like lesions over trunk, limbs

widespread

erythematous

fine

scaly

lesions often erupt after URTI

Question 9

signs of plantopalmer psoriasis

Answer 9

erythematous plaques with pustules on palms and soles

Question 10

signs of generalised pustular psoriasis

Answer 10

pustules distributed over limbs and torso

Question 11

nail signs of psoraisis

Answer 11

pitting

onycholysis - lifting of the nail-plate from the nail bed

subungal hyperkeratosis

salmon patch on nail

if have nail signs - more likely to get arthritis

Question 12

joint signs of psoriasis

Answer 12

seronegative arthritis with 6 possible presentations:

• monoarthritis
• distal asymettrical oligoarthritis - distal interphalangeal joints
• dactylitis - interphalangeal arthritis and flexor tenosynovitis
• rheumatoid arthritis like (symettrical polyarthritis)
• arthritis mutilans (telescoping of the digits)
• ankolysing spondylitis

poor correlation between joint and skin involvement

Question 13

pathology of psoriasis

Answer 13

excess proliferation of epidermal cells - rapid cell turnover possibly mediated by cytokines released by lymphocytes in the dermis

accelarated upward migration of immature keratinocytes

Question 14

investigations for psoriasis

Answer 14

majority of pts dont need any

• guttate psoriasis
  
  • anti-streptolysin-O titre
  • throat swab
• flexural lesions
  
  • skin swabs - exclude candidiasis
• nail
  
  • analyse nail clippings to exclude onychomycosis - fungal infection
• joint involvement
  
  • rheumatoid factor - negative
  • radiographs - distal interphalangeal joints
  • erosions
  • periarticular osteoporosis
  • pencil in cup deformity - whittling and cupping of phalanges
  • sacrolilitis