A 48-year-old man is brought to the emergency department with a stab wound to his chest. The wound is treated in the emergency room. Three months later he develops a firm 4 x 3 cm nodular mass with intact epithelium over the site of the chest wound. On local examination, the scar is firm, non-tender, and there is no erythema. The mass is excised and microscopic examination reveals fibroblasts with plentiful collagen. Which of the following processes is most likely related to the series of events mentioned above?

Foreign body response from suturing

Poor wound healing from diabetes mellitus

A 65-year-old woman presents to a dermatology clinic complaining about a couple of well-demarcated, dark, round skin lesions on her face. She claims she has had these lesions for 3 or 4 years. The lesions are painless, not pruritic, and have never bled. However, she is moderately distressed about the potential malignancy of these lesions after she heard that a close friend was just diagnosed with a melanoma. The medical history is unremarkable. Physical examination reveals a few well-demarcated, round, verrucous lesions, with a stuck-on appearance, distributed on the patient's back and face (see image). Under a dermatoscope, the lesions showed multiple comedo-like openings, milia cysts, and a cerebriform pattern. What is the best next step of management?

Reassure the patient and provide general recommendations

A 45-year-old man comes to his primary care provider for a routine visit. The patient mentions that while he was cooking 5 days ago, he accidentally cut himself with a meat cleaver and lost the skin at the tip of his finger. After applying pressure and ice, the bleeding stopped and he did not seek treatment. The patient is otherwise healthy and does not take any daily medications. The patient’s temperature is 98.2°F (36.8°C), blood pressure is 114/72 mmHg, pulse is 60/min, and respirations are 12/min. On exam, the patient demonstrates a 0.5 x 0.3 cm wound on the tip of his left third finger. No bone is involved, and the wound is red, soft, and painless. There are no signs of infection. Which of the following can be expected on histopathological examination of the wounded area?

Deposition of type III collagen

Epithelial cell migration from the wound borders

Neutrophil migration into the wound

Scarring process and management for USMLE Step 2 CK: High-Yield Surgery Lessons

Wound Healing - The Repair Crew

Phases: A sequential, overlapping process to restore tissue integrity. Key players change with time.

⭐ In the remodeling phase, Type III collagen (weak) is replaced by Type I (strong). Wound strength is only ~80% of the original tissue's strength at its peak.

Abnormal Scarring - Keloid vs. HTS

Keloid vs. Hypertrophic Scar Comparison Table

Feature	Keloid	Hypertrophic Scar (HTS)
Borders	Grows beyond original wound margins	Confined within original wound
Onset	Months to years post-injury	Within 4-8 weeks post-injury
Collagen	Disorganized, thick Type I & III	Organized, parallel Type III
Genetics	Strong predisposition (esp. African descent)	No major predisposition
Prognosis	Rarely regresses; high recurrence post-excision	May regress; better response to treatment

Scar Management - The Fixer‑Uppers

Conservative (First-Line):
- Silicone Gel Sheeting/Ointment: ↑ hydration, modulates fibroblast activity. Apply for >12 hrs/day.
- Pressure Therapy/Massage: Especially for extensive burn scars; garments worn 23/7.
Intralesional Injections (For Hypertrophic/Keloids):
- Corticosteroids (Triamcinolone): ↓ collagen synthesis & inflammation.
- 5-Fluorouracil (5-FU): Inhibits fibroblast proliferation; often combined with steroids.
Advanced Therapies:
- Laser Therapy: Pulsed-dye laser for redness; fractional lasers for texture.
- Surgical Excision: High recurrence for keloids unless combined with adjuvant therapy (e.g., steroids, radiation).

⭐ Keloids invade tissue beyond the original wound borders, unlike hypertrophic scars. Excision alone can lead to a larger keloid; always use adjuvant therapy.

Hypertrophic vs. Keloid Scars: Key Differences

High‑Yield Points - ⚡ Biggest Takeaways

Keloids are marked by disorganized Type I & III collagen and grow beyond original wound borders.

Hypertrophic scars contain organized Type I collagen and stay within the wound's initial margins.

The remodeling phase is key: weaker Type III collagen is replaced by stronger Type I collagen.

A healed wound's final tensile strength only reaches about 80% of the original tissue's strength.

Impaired healing is strongly associated with infection, ischemia, malnutrition (especially Vitamin C deficiency), and corticosteroids.

Wound dehiscence is the post-operative separation of wound layers, a surgical emergency.

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Scarring process and management