Primary Skin Lesions Overview

Primary Skin Lesions

• Primary skin lesions appear on healthy skin, directly caused by the skin disease.
• Various forms, including macules, papules, nodules, plaques, wheals, vesicles, pustules, bullae, and cysts.

Macule

• A flat, discolored area of skin, with no visible change in thickness or texture.
• Size is less than 1 cm.
• Possible causes include hyperemia, dilated blood vessels, extravasation of red blood cells and changes in melanin production (e.g., freckles, vitiligo).

Papule

• A solid, raised area of skin
• Less than 1 cm in diameter
• Potential causes include epidermal thickening or cellular infiltration (e.g., skin tags, warts).

Nodule

• Solid, raised, and palpable lesion deeper than papule
• Size ranges from 0.5 cm to 5 cm
• Can be caused by various inflammations, growths or infections.

Plaque

• Elevated and solid area of skin, larger than 1 cm.
• May be flat or slightly raised. May be formed from many papules.

Wheal

• Elevated, transient skin lesion that is red or pale in color.
• Develops due to edema of the dermis
• Typically fades within 24 hours.

Vesicle

• Elevated skin lesion, filled with clear/serous fluid.
• Less than 1 cm in diameter

Pustule

• Vesicle containing purulent fluid (pus).

Bulla

• Fluid-filled lesion larger than 1 cm, often containing serous fluid.

Cyst

• A sac-like structure containing fluid or semisolid material.
• Enclosed within connective tissue.