Terms used to describe skin lesions

Primary lesions
• Abscess: a localised collection of pus in a cavity, > 1 cm in diameter
• Burrow: a linear or curvilinear papule, caused by a burrowing scabies mite (panel A )
• Comedone: a plug of keratin and sebum wedged in a dilated pilosebaceous orifice (panel B)
• Macule: a circumscribed flat area of altered colour, e.g. freckle (panel C)
• Papilloma: a projecting nipple-like mass, e.g. skin tag (panel D)
• Papule: a discrete elevation of skin that may be changed in colour (panel E). Those arising from the subcutis may be felt rather than
seen. Larger lesions (> 1 cm) are referred to as nodules
• Petechiae, purpura and ecchymosis: petechiae are pinhead-sized flat macules of extravascular blood in the dermis. Purpura are
larger and may be palpable. Ecchymosis (‘bruise’) is where bleeding involves deeper structures (see panel F)
• Plaque: a raised area of skin with a flat top, several cm in diameter, e.g. psoriasis (panel G)
• Pustule: a visible accumulation of pus in a blister (panel H)
• Scale: a flake arising from the stratum corneum, e.g. psoriasis (panel I)
• Telangiectasia: visible dilatation of small cutaneous blood vessels (panel J)
• Vesicle and bulla: a small (∼ several mm) and a larger (∼ several cm) fluid-filled blister respectively, e.g. pemphigoid (panel K)
• Weal: an evanescent discrete area of dermal oedema, usually white due to masking of local blood supply by fluid, e.g. a nettle sting

Secondary lesions
• Atrophy: an area of thin, translucent skin due to loss of epidermis, dermis or subcutaneous fat, e.g. excess topical corticosteroids
• Crust: dried exudate of blood or serous fluid, e.g. eczema
• Excoriation: a linear ulcer or erosion resulting from scratching
• Erosion: an area of skin denuded by complete or partial loss of the epidermis
• Fissure: a slit-shaped deep ulcer, e.g. irritant dermatitis of the hands
• Scar: replacement of normal structures by fibrous tissue at the site of an injury
• Sinus: a cavity or channel that permits the escape of pus or fluid
• Stria: a linear, atrophic, pink, purple or white band due to connective tissue changes, e.g. Cushing’s syndrome
• Ulcer: an area from which the epidermis and at least the upper part of the dermis have been lost