Configuration
- Linear
- Annular
- Arciform
- Polycyclic
- Iris
- Grouped
- Herpetiform
- Zosteriform
Distribution
Many diseases have predilection for specific body sites
- Psoriasis:
- Extensors (elbows and knees)
- Scalp
- Acne :
- Face
- Upper chest, Upper back
- Photosensitive eruption: Mainly face, forearms & V-Chest (with sparing of photoprotected areas e.g. upper eyelids, retro-auricular an sub-mental)
Colour in Dermatology
- Red: Vascular lesions e.g. port wine stain also, inflammatory disorders like psoriasis
- Blue:
- Blue nevus
- Mongolian spot
- Yellow: Xanthoma
- White: Vitiligo
- Black: Melanocytic nevus & melanoma
- Purple or (Violaceous) : Lichen planus
