Primary Lesions
Macule – flat lesion(<1cm) eg: freckle
Papule – solid, elevated lesion (<1cm) eg: whitehead
Patch – large macule (>1cm) eg: vitiligo, post-inflammatory hyperpigmentation
Plaque – elevated lesion(>1cm) eg: psoriasis
Nodule – solid, elevated lesion (>1cm) into dermis eg: erythema nodosum
Pustule – elevated lesion with visible exudate eg: folliculitis
Vesicle – elevated lesion containing clear fluid (<0.5cm diameter) eg: chicken pox
Bullae – elevated lesion containing clear fluid (>0.5cm diameter) eg: bullous impetigo
Wheal – oedema in dermis (V/D and incresed permeability) eg: mosquito bite, food allergy
Abscess – pus-filled swelling below skin (pus may be invisible, but features of inflammation present) eg: boils, carbuncles
Cyst – sac contaning liquid or semisolid material in cavity (well-defined margin)
(1) epidermal cyst – contain keratinous material (lined with squamous epithelium)
(2) pilar cyst – originated from hair follicle blocked by keratin (lined with multilayered epithelium)
Secondary Lesions
Excoriation – produced by scratch (in epidermis)
Abrasion – caused by friction or mechanical trauma (in epidermis)
Erosion – partial loss of epidermis (non-scarring) eg: acid corrosive, herpes zoster
Ulcer – complete loss of epidermis together with partly dermis (scarring) eg: bed sore, diabetic foot
Crust – cellular debris (together with dried blood, pus, serum) eg: impetigo, scratch mole until bleed
Scale – abnormal shedding or accumulation of stratum corneum eg: eczema, psoriasis
Fissure – linear cleft of epidermis and part of dermis eg: cracked heel (pain may be suffered in deeper fissure)
Scar – new connective tissue in dermis eg: hypertrophic scar, keloid
Telangiectasia – focal dilation of superficial small vessel (disappear when pressure)
Skin Atrophy – decreased cells in epidermal or dermal or fat layer
(1) epidermal atrophy – fine line, wrinkle
(2) dermal atrophy – skin-graft area, Discoid lupus erythematosus
(3) lipoatrophy – repeated injections of drugs(insulin)
Lichenification -focal skin thickness caused by repeated scatch, rubbing
- Characteric triad of lichenification – epidermis thickening, hyperpigmentation and skin markings (eg: lichen simplex chronicus)
Dr. Aye Min Htoo
(Dermatologist)
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