skin lesion

BASIC SKIN LESIONS

Introduction

  • Presenter: Dr. Rabia Ghafor

  • Role: Professor of Dermatology at JPMC

STRUCTURE OF SKIN

Key Components

  • Hair Follicle

  • Sweat Gland

  • Fat

  • Epidermis

  • Dermis

  • Hypodermis

  • Connective Tissue

  • Blood Vessels

TYPES OF SKIN LESIONS

Classification

  1. Primary Skin Lesions
       - Definition: Develop as a direct result of disease processes.

  2. Secondary Skin Lesions
       - Definition: Evolve from primary lesions or develop as a consequence of the patient's activities.

PRIMARY SKIN LESIONS

Types

  • Macule

  • Patch

  • Plaque

  • Papule

  • Pustule

  • Nodule

  • Vesicle

  • Bullae

  • Abscess

  • Wheal

Macule

  • Definition: A flat, circumscribed lesion showing a change in color without a change in consistency.

  • Characteristics:
      - Nonpalpable.
      - Size: 0.5 cm - 1 cm.

Patch

  • Definition: A large macule.

  • Size: Greater than 1 cm.

  • Characteristics: May have scaling, examples include vitiligo and melasma.

Plaque

  • Definition: A circumscribed, superficial, elevated plateau area.

  • Size: 1.0 cm - 2.0 cm in diameter.

Papule

  • Definition: A circumscribed, raised lesion of epidermal or dermal origin.

  • Size: 0.5 cm - 1.0 cm in diameter.

Pustule

  • Definition: A circumscribed superficial cavity of the skin that contains a purulent exudate.

  • Colors: May be white, yellow, greenish-yellow, or hemorrhagic.

Nodule

  • Definition: A large, firm lesion raised above the surface of surrounding skin.

  • Size: 0.5 cm - 5.0 cm.

  • Characteristics: The depth of involvement differentiates a nodule from a large papule; can be smooth, keratotic, ulcerated, or fungating.

Vesicle

  • Definition: A small, fluid-filled lesion.

  • Size: Less than 0.5 cm in diameter.

  • Characteristics: Raised above the surrounding skin; fluid is often visible, making lesions translucent.

Bullae

  • Definition: A fluid-filled, raised lesion.

  • Size: Greater than 0.5 cm in diameter.

  • Example: Bullous pemphigoid.

Abscess

  • Definition: A localized collection of pus deep in the dermis or subcutaneous tissue.

Wheal

  • Definition: A transient swelling of skin that disappears within 24 hours.

  • Mechanism: Formed due to sudden extravasation of fluid in the dermis.

  • Example: Urticaria.

SECONDARY SKIN LESIONS

Types

  • Scales

  • Crusts

  • Excoriation

  • Erosions

  • Petechiae

  • Purpura

  • Ulcers

  • Atrophy

  • Cysts

  • Keloid

  • Hypertrophic Scars

  • Telangiectases

Scales

  • Definition: Laminated masses of keratin, which may be dry or greasy.

Crust

  • Definition: Dried exudate of body fluids such as blood or serous fluid.

  • Characteristics: May be yellow or red.

Excoriation

  • Definition: A linear erosion caused by scratching, rubbing, or picking.

Erosion

  • Definition: Open areas of skin resulting from loss of part or all of the epidermis.

Scars

  • Definition: Areas of fibrosis that replace normal skin after injury.

Hypertrophic Scar

  • Definition: Limited to the area of damaged skin; prone to occur under tension on a healing wound.

Keloid

  • Definition: A type of hypertrophic scar that extends beyond the original wound margin.

Atrophy

  • Definition: Thinning of the skin that may appear dry and wrinkled.

  • Causes: Chronic sun exposure, aging, inflammatory and neoplastic skin diseases, long-term use of potent topical corticosteroids.

Petechiae

  • Definition: Non-blanchable punctate foci of hemorrhage.

Purpura

  • Definition: A larger area of hemorrhage that may be palpable; purpura does not blanch.

Erythema

  • Definition: Redness of skin due to dilatation of blood vessels.

Telangiectases

  • Definition: Permanent dilatation of cutaneous blood vessels.

LESION CONFIGURATION

Configuration Characteristics

  • Configuration refers to the shape of a single lesion and the arrangement of clusters of lesions:
      - Linear: Shape of a straight line.
      - Annular: Rings with central clearing.
      - Serpiginous: Lesions with linear, branched, and curving elements.
      - Herpetiform: Grouped papules or vesicles arranged like those of herpes simplex infection.

  

TEXTURE OF SKIN

Texture Implications

  • Some skin lesions have a visible or palpable texture that suggests a diagnosis.

  • Lichenification: Thickening of the skin with accentuation of normal skin markings.

Visual Examples of Skin Lesions

  • Plaque

  • Papule (Linear Arrangement)

  • Patch (Clinically)

  • Vascular Patch

  • Nodule (Big)

  • Papule (Small)

  • Cutaneous Larva Migrans

  • Blister