5.2 Secondary Cutaneous Lesions & Wound Repair

5.2 Secondary Cutaneous Lesions & Wound Repair

Secondary Cutaneous Lesions: Evolution, Trauma & Wound Repair

Secondary lesions do not arise spontaneously. Instead, they develop during the late stages of a skin disease or evolve from pre-existing primary lesions due to external physical trauma, mechanical scratching, chronic friction, secondary microbial infection, or the natural physiological wound healing cascade.

+-----------------------------------------------------------------------------------+
|                       Secondary Lesion Pathological Cascade                       |
+-----------------------------------------------------------------------------------+
| SURFACE LOSS (Epidermal Only) │ Erosion (Moist, Basement Intact ──> NO SCAR)      |
| SURFACE LOSS (Epidermal/Dermal)│ Ulcer (Excavative Necrosis ──> ALWAYS SCARS)      |
| LINEAR CLEAVAGE / CRACK       │ Fissure (Penetrates into Dermis ──> Scar Risk)    |
| MECHANICAL SCRATCHING         │ Excoriation (Scratch Marks, Fingernail Trauma)    |
| ACCUMULATED DEAD KERATIN      │ Scale (Shedding Stratum Corneum Plates)           |
| DRIED BODILY EXUDATE          │ Crust (Scab of Dried Blood, Pus, or Sebum)        |
| FIBROUS WOUND RESTORATION     │ Scar / Cicatrix (Normal Collagen Replacement)     |
| ABERRANT HYPERTROPHIC SCAR    │ Keloid (Overgrowth Beyond Original Wound Borders) |
+-----------------------------------------------------------------------------------+

1. Lesions Involving Loss of Cutaneous Integrity

• Erosion: A shallow, moist, circumscribed, slightly depressed lesion representing the partial or total loss of the superficial epidermis. Crucially, the underlying dermo-epidermal basement membrane remains intact, and the papillary dermis is undamaged. Erosions frequently develop when the fragile roof of an intraepidermal vesicle or bulla ruptures, or following superficial chemical peel desquamation. Because dermal collagen networks are unaffected, erosions heal completely through basal keratinocyte re-epithelialization without leaving scar tissue.
• Ulcer: A deep, excavative, crater-like depression involving the necrotic destruction and loss of the complete epidermis, the basement membrane, and extending into the papillary or reticular dermis (and occasionally deeper into subcutaneous adipose or muscle tissue). Ulcers frequently weep serosanguinous exudate and feature irregular, indurated borders. Because the dermal connective tissue framework is destroyed, ulcers heal strictly through granulation tissue formation and myofibroblast contraction, invariably leaving permanent fibrous scar tissue. Clinical examples include decubitus pressure ulcers, venous stasis ulcers, diabetic neuropathic ulcers, and syphilitic chancres. Ulcers are an absolute contraindication for all esthetic services.
• Fissure: A distinct linear cleavage, crack, or groove extending through the epidermis and penetrating into the underlying papillary dermis. Fissures develop when skin loses its physiological elasticity and tensile pliability due to extreme epidermal desiccation, hyperkeratosis, or persistent environmental exposure. Fissures are sharply defined, intensely painful, and prone to bleeding. Common clinical sites include chapped lips (angular cheilitis), interdigital webbed spaces in tinea pedis (athlete's foot), and severely calloused, cracked heels.
• Excoriation: A superficial, hollowed-out, linear or punctate abrasion produced by mechanical friction, fingernails, scratching, or habitual skin picking. Excoriations are usually confined to the epidermis but may reach the papillary dermis if scratching is intense. They are frequently seen in pruritic conditions such as scabies, atopic dermatitis, insect bites, or psychiatric dermatillomania (neurotic excoriation).

2. Material Deposited on the Cutaneous Surface

• Scale: Thin, dry, or greasy plate-like laminations composed of shedding, cornified keratinocytes of the stratum corneum. Scaling indicates abnormal desquamation, accelerated epidermal transit times, or parakeratosis (retention of nuclei in the stratum corneum). Clinical examples include dry skin (xerosis cutis), dandruff (pityriasis capitis), seborrheic dermatitis (greasy, yellowish scales), and psoriasis (thick, adherent, micaceous silvery-white scales).
• Crust: A solid, elevated encrustation formed when bodily exudates—such as serous fluid, purulent pus, or blood—dry, coagulate, and crust over on the skin surface. Crusts represent a protective biological "scab" over an underlying weeping or eroded wound. Clinical examples include the characteristic honey-colored (amber) gummy crusts of bacterial impetigo, dried scabs over excoriated lesions, and weeping post-extraction serous scabs.

3. Fibrous Tissue Alterations & Healing Anomalies

• Scar (Cicatrix): A permanent structural replacement of normal cutaneous architecture by dense, fibrous collagenous connective tissue following deep injury that penetrates into the dermis. During dermal wound repair, fibroblasts deposit disorganized parallel bundles of Type I and Type III collagen, lacking the elastic fibers, hair follicles, sebaceous glands, and sudoriferous ducts of normal skin. Scars may be atrophic (depressed, pitted scars seen in acne or varicella) or hypertrophic (elevated within original wound boundaries).
• Keloid: An abnormal, thick, raised, rubbery, nodular overgrowth of dense, hyalinized collagenous scar tissue that extends laterally beyond the anatomical boundaries of the original wound, invading surrounding uninjured tissues. Keloids are driven by uninhibited fibroblast proliferation and defective collagenase degradation. They exhibit a high tendency to recur following surgical excision and possess a strong hereditary predisposition, occurring with markedly higher frequency in Fitzpatrick skin phototypes IV through VI (individuals of African, Mediterranean, Asian, or Hispanic descent). Common trigger sites include earlobes (piercings), sternum, shoulders, and jawline. Aggressive mechanical or ablative esthetic procedures are strictly contraindicated over keloidal skin.

Primary vs. Secondary Dermatological Lesions Comparison Matrix

The following clinical matrix details the distinguishing anatomical markers, size boundaries, and esthetic procedural boundaries for all core dermatological lesions: