Second Intention Healing After Mohs: When Leaving the Wound Open Beats Stitches

Patients who complete Mohs micrographic surgery often expect the day to end with sutures. Sometimes it does not. Instead, the surgeon dresses the open wound, hands over a care sheet, and explains that the body will fill the defect on its own over several weeks. This approach is called second intention healing, and while it can sound like doing nothing, it is a deliberate reconstructive choice with more than a century of clinical precedent behind it.

What second intention healing actually is For an independent overview, see Mohs surgery and reconstruction, society overview.

After tumor removal, a surgeon has three broad options: close the wound directly or with a flap or graft (primary closure), leave it open to heal on its own (second intention), or a hybrid where partial closure shrinks the defect and the remainder granulates. In second intention healing, the wound passes through predictable phases. Inflammation clears debris in the first days. Granulation tissue, a bed of new capillaries and fibroblasts, fills the defect from the base upward. Myofibroblasts then contract the wound edges inward, often shrinking the visible defect by a substantial margin. Finally, keratinocytes migrate across the surface to re-epithelialize it. The result is a scar, but frequently a flat, pale one that blends well with surrounding skin.

Where it works: the concave rule

The most cited framework comes from work published in the early 1980s that mapped facial healing outcomes by anatomic zone. The pattern that emerged is straightforward: concave surfaces heal well by second intention, convex surfaces heal poorly. Favorable sites include the medial canthus (the inner corner of the eye), the alar groove, the concha and other hollows of the ear, the temple, and the nasolabial fold region. In these concavities, wound contraction pulls tissue into the hollow rather than distorting it, and the mature scar often sits flush with the surrounding contour. Some surgeons argue that a second intention result at the medial canthus routinely rivals or exceeds a flap, because flaps in that area risk webbing and distortion of the eyelid margin.

Convex sites tell the opposite story. The nasal tip, the malar cheek, the chin, and the vermilion lip tend to heal with depressed, shiny, or hypopigmented scars when left open, because contraction on a curved prominence flattens or dimples the surface. Wounds near free margins, meaning the eyelid, the nostril rim, and the lip edge, carry an additional mechanical risk: contraction can pull the margin out of position, causing ectropion of the eyelid or notching of the lip. These outcomes are functional problems, not just cosmetic ones, so most surgeons close such defects surgically.

Why a surgeon might choose it even outside the ideal zones

Anatomy is not the only variable. Second intention is often preferred when the patient takes anticoagulants and flap surgery would raise bleeding risk, when the patient is frail or cannot tolerate a longer procedure, or when tumor margins were complex and the surgeon wants an unobstructed view of the site during early follow-up. That last point matters: a flap covers the wound bed, and if a recurrence emerges beneath it, detection can be delayed. An open, granulating wound leaves nothing hidden. Lower leg defects in older patients are another common scenario, since tissue laxity there is poor and closures are prone to dehiscence, though healing on the shin is notoriously slow and requires patience.

The honest tradeoffs

The main costs are time and maintenance. A defect one to two centimeters across on a favorable facial site may take four to eight weeks to re-epithelialize. Larger wounds or wounds on the lower extremity can take considerably longer. During that period the patient performs daily wound care, typically gentle cleansing followed by a bland occlusive ointment such as plain petrolatum and a nonstick dressing. The evidence on this point is consistent: moist wound healing outpaces dry healing, and letting a wound scab over slows keratinocyte migration. Antibiotic ointments are generally unnecessary and carry a real risk of allergic contact dermatitis, particularly with neomycin and bacitracin.

Infection rates in granulating Mohs wounds are low, generally comparable to sutured wounds when basic hygiene is followed. Bleeding in the first 48 hours and hypertrophic scarring in a minority of patients are the other risks worth naming. If the mature scar disappoints, revision remains possible: dermabrasion, laser resurfacing, or a delayed surgical revision can be performed months later, and starting with second intention forecloses none of these options.

The bottom line

Second intention healing is not a lesser option or a sign that reconstruction was skipped. On concave facial sites, in anticoagulated or medically fragile patients, and in situations where surveillance of the wound bed matters, it is often the evidence-based first choice. The reasonable questions to ask a surgeon are simple ones: is my defect on a concave or convex surface, is it near a free margin, roughly how long will healing take, and what does the daily care routine look like. The answers, not the presence or absence of stitches, are what predict the final result.

Related reading: Reconstruction after Mohs surgery.