Dermatology
Psoriasis
건선
T-cell mediated chronic inflammatory skin disease
- How common
- 2–3% of population
- Typical age
- Bimodal: 20s and 50s
What is it?
IL-23/Th17 axis drives keratinocyte hyperproliferation forming thick scaly plaques.
Commonly affected: Scalp, elbows, knees, sacrum, nails
How it develops
- TriggerInfection, stress, drug exposure
- DC activationIL-23 release activates Th17 cells
- IL-17/IL-22Drive keratinocyte proliferation/inflammation
- Plaque formationThick silvery plaques form
Symptoms
- Silvery scalesThick silvery scale on erythematous base
- Auspitz signPinpoint bleeding when scale is removed
- Nail changesPitting, oil drops, onycholysis
- Joint pain~30% develop psoriatic arthritis
- PruritusVariable, less than eczema
How it is examined
- PASI scoringArea, erythema, scale, thickness
- Nail examLook for pitting, oil drop
- Joint examCheck DIP joints, dactylitis
Imaging
X-ray may show "pencil-in-cup" deformity if arthritis.
- Pencil-in-cup deformity
- DIP involvement
MRI shows synovitis if assessing arthritis.
- Synovitis
- Enthesitis
Non-surgical care
- Topical steroid + Vit D analogCalcipotriol ± betamethasone
- Phototherapy (NB-UVB)Standard for moderate psoriasis
- Coal tarEffective for scalp psoriasis
- MethotrexateSystemic for moderate–severe
Conservative options are generally tried first. Medications listed here can have side effects — discuss them with your prescriber.
When surgery is considered
Severe/arthritis/refractory
Procedures that may be discussed
- Biologics (IL-17, IL-23, TNF inhibitors)
- Apremilast (PDE4)
- Cyclosporine
Outlook
Chronic relapsing; biologics achieve >90% clearance.