Overview Terminology Used to Describe Skin Lesions Term Description Photo Rash/eruption Describes more widespread skin involvement, which can be composed of several lesions with primary and secondary morphologies e.g., chicken pox Macule Flat lesion < 1 cm in diameter e.g., freckles Patch Flat lesion > 1 cm in diameter e.g., cafe-au-lait spot Papule Elevated lesion that is < 1 cm in diameter Palpable lesion e.g., acne Plaque Elevated lesion that is > 1 cm diameter Palpable Palpable Papules and Plaques e.g., plaque psoriasis Nodule Palpable, solid, and round or ellipsoidal lesion of dermal origin e.g., erythema nodosum Vesicle Small fluid containing lesion that is < 0.5 cm e.g., zoster Pustule Vesicle containing purulent material May be white or yellow Is not always infected (e.g. sterile pustule) e.g., pustular psoriasis Wheal Edematous papule or plaque caused by swelling in the dermis e.g., urticaria Bulla Large fluid containing lesion that is > 0.5 cm Can be multi-loculated e.g., bullous pemphigoid Cyst Closed epithelial-lined cavity or sac containing liquid or semi-solid material Fluctuant as it contains liquid e.g., epidermal inclusion cyst Purpura Non-palpable purpura petechiae (< 3 mm) ecchymoses (> 5 mm) Palpable purpura Indicates extravasation of red blood cells into the skin e.g., small vessel vasculitis Petechiae Small red, purple, or brown pinpoint dots indicative of hemorrhage Non-blanching e.g., thrombocytopenia Ecchymoses Purple or brown lesions covering a larger area Non-blanching e.g., traumatic bruise Lichenification Accentuated skin markings in thick epidermis due to scratching e.g., atopic dermatitis Keloid Irregular plaque-like lesion resulting from abnormal healing and extends beyond the borders of initial wound Hyperkeratosis Increased thickness of stratum corneum seen in chronic dermatitis e.g., calluses Parakeratosis Hyperkeratosis with retention of nuclei in stratum corneum and thinning of stratum granulosum e.g., classic finding in psoriasis Annular Ring shaped lesion e.g., ringworm infection