Foundations of Cutaneous Surgery

Hemostasis initiates within seconds via platelet aggregation and fibrin clot formation. Neutrophils dominate the first 24–48 hours, followed by macrophages that orchestrate the transition to proliferation. Growth factors including PDGF, TGF-β, and VEGF are released, establishing the foundation for tissue repair.

Fibroblasts migrate into the wound, synthesizing collagen (predominantly type III initially, later replaced by type I). Angiogenesis creates new blood supply. Epithelial cells migrate from wound edges and adnexal structures. Wound contraction, driven by myofibroblasts, reduces wound size by up to 40–80% in secondary intention healing.

Collagen crosslinking and reorganization along tension lines progressively increases tensile strength. At 1 week, wound strength is approximately 3% of normal; at 3 weeks, 20%; at 3 months, 50%; reaching a maximum of approximately 80% by 1 year. This is why suture removal timing and activity restrictions are anatomically specific.

Multiple patient and local factors can significantly impair wound healing. Identifying these preoperatively allows for risk mitigation and appropriate patient counseling.

Both represent abnormal scar formation, but they differ in behavior and management. Hypertrophic scars remain within wound boundaries, develop within 4–8 weeks, and often improve spontaneously over 1–2 years. Keloids extend beyond the original wound, may develop months after injury, and rarely regress spontaneously. Keloids are more common in darker skin types (Fitzpatrick IV–VI) and at specific anatomic sites: earlobes, shoulders, presternal chest, and upper back.

The temporal branch of CN VII (facial nerve) is the most commonly injured motor nerve in dermatologic surgery. It crosses the zygomatic arch within the superficial temporal fascia (temporoparietal fascia), approximately 2 cm anterior to the tragus. Injury results in ipsilateral brow ptosis and inability to raise the eyebrow. The marginal mandibular branch runs superficially (within 1–2 cm below the mandibular border) and is vulnerable during surgery on the jawline and submandibular area. Injury causes inability to depress the lower lip, resulting in asymmetric smile. The spinal accessory nerve (CN XI) crosses the posterior triangle of the neck superficially, approximately 1 cm above Erb’s point. Injury results in shoulder drop and inability to abduct the arm above 90 degrees.

The supraorbital and supratrochlear nerves supply the forehead and anterior scalp. The infraorbital nerve exits 1 cm below the orbital rim in the mid-pupillary line, supplying the cheek, lateral nose, and upper lip. The mental nerve exits the mental foramen (below the second premolar), supplying the chin and lower lip. Damage to these nerves causes numbness in their respective territories but typically recovers over weeks to months (neurapraxia).

RSTLs represent the orientation of dermal collagen and elastic fibers at rest. Excisions and closures aligned parallel to RSTLs produce the least conspicuous scars. On the face, RSTLs generally follow expression lines (forehead creases, crow’s feet, nasolabial folds). On the trunk and extremities, Langer’s lines provide a reasonable approximation. To identify RSTLs clinically: pinch the skin perpendicular to suspected lines. The direction with the most laxity confirms the RSTL orientation.

The nose, lips, eyelids, ears, forehead, and cheeks each comprise distinct cosmetic subunits defined by contour, texture, and color boundaries. The subunit principle (Burget and Menick) states that when ≥50% of a subunit is lost, replacing the entire subunit with a flap or graft produces a superior cosmetic result compared to patching the defect alone. This principle is most commonly applied to nasal reconstruction.

Key elements: cardiac devices (pacemakers, ICDs. Affects electrosurgery protocol), prosthetic joints or heart valves (assess prophylactic antibiotic need per current AHA/AAOS guidelines), immunosuppression (organ transplant, biologics, chemotherapy), bleeding disorders, and prior adverse reactions to anesthesia.

Anticoagulants and antiplatelet agents are the most critical medications to review. Current evidence supports continuing aspirin and warfarin (at therapeutic INR) for most cutaneous procedures. DOACs and dual antiplatelet therapy require individualized assessment. Detailed management protocols are covered in Module 10. Supplements to discontinue 1–2 weeks preoperatively: fish oil, vitamin E (high dose), ginkgo biloba, garlic supplements, turmeric/curcumin. All associated with increased bleeding tendency.

Informed consent must include: diagnosis and nature of the procedure, expected benefits (cure rates, cosmetic outcomes), risks (bleeding, infection, scarring, nerve injury, recurrence), alternatives (standard excision, radiation, observation), and expected recovery timeline. For Mohs surgery specifically, discuss the iterative nature (multiple stages), typical duration (2–4 hours), and reconstruction planning.

Standardized preoperative photographs serve as medical-legal documentation and surgical planning aids. Photograph the lesion with and without markings, include a ruler for scale, and capture the surrounding anatomic context. Use consistent lighting and background. Multiple angles are essential for 3D anatomic sites (nose, ear).