Abstract: Birthmarks and various types of scars are common cosmetic skin lesions in dermatology, including pigmented birthmarks, vascular birthmarks, superficial scars, hypertrophic scars, atrophic scars, and keloids. Different lesions vary significantly in histological depth, target tissue characteristics, and recurrence tendency, corresponding to different treatment techniques, clinical difficulty, and risk levels. This article, based on the principle of selective photothermolysis and relevant clinical consensus on skin tissue remodeling, systematically reviews the current mainstream techniques for birthmark removal and scar repair, classifies various lesions into difficulty levels, and summarizes the risk points and avoidance strategies in the treatment process, providing a reference for standardized clinical assessment and doctor-patient communication. This article is a specialized science popularization research article and does not constitute an individualized treatment plan; specific diagnosis and treatment require in-person evaluation.
Keywords: birthmark; scar repair; selective photothermolysis; fractional laser; pulsed dye laser; keloid; pigmentation abnormalities; risk control
I. Introduction
Birthmarks typically refer to localized pigmented or vascular skin lesions that are congenital or appear early after birth; scars are repair products formed by the abnormal proliferation and remodeling of fibroblasts and collagen after skin tissue has been traumatized. With the increasing demand for improved skin appearance, technologies such as phototherapy, local drug injection, surgery, and physical pressure are widely used in this field. However, the market is rife with problems such as exaggerated claims about efficacy, misjudgments of the complexity of skin lesions, and neglect of the risk of complications.
The Birthmark and Scar Department of Zhengzhou Fuda Dermatology Hospital has long been engaged in the classification, assessment, and sequential intervention of birthmarks and scars. Clinical experience has shown that the same treatment method applied to different subtypes of lesions can have vastly different effects, difficulties, and risks. A standardized treatment procedure should begin with imaging assessments such as dermoscopy and skin CT scans to determine the depth of the target tissue, blood supply, and collagen distribution, before matching the appropriate technique. Simultaneously, patients should be objectively informed of the upper limit of efficacy, the treatment duration, and potential adverse reactions.
II. Classification, Mainstream Techniques, and Difficulty Levels of Birthmark Removal
Birthmarks are divided into two main categories: pigmented birthmarks and vascular birthmarks. The target chromophores of the two are completely different, and there are significant differences in equipment selection, treatment difficulty, and prognosis.
2.1 Pigmented birthmarks (nevus of Ota, café-au-lait spots, blue nevus, hairy nevus)
Core principle: Q-switched lasers and picosecond lasers utilize selective photothermal effects to target and break down melanin granules in the dermis/epidermis, which are then eliminated by macrophages through metabolism.
1. Nevus of Ota
Commonly used technologies: 755nm alexandrite Q-switched/picosecond laser, 1064nm Nd:YAG laser.
Difficulty level: Medium to low.
Clinical characteristics: Melanin is mostly concentrated in the dermis, with a clear target chromophore and sufficient evidence-based support. Most cases can be significantly lightened after 3–6 standardized treatments, with intervals of 4–6 months; however, if the sclera or deep periocular skin lesions are involved, the treatment becomes more difficult and requires joint ophthalmological examination to screen for intraocular pressure and glaucoma risk.
Main risks: post-inflammatory hyperpigmentation, hypopigmentation, and accidental injury during periocular treatment.
2. Café-au-lait spots
Commonly used technologies: 755nm picosecond laser, Q-switched laser.
Difficulty level: Medium to high.
Clinical features: Increased melanin in the basal layer of the epidermis, with significant individual variability. Some café-au-lait spots respond well to treatment, while a few show a tendency to relapse; multiple café-au-lait spots warrant attention for systemic diseases such as neurofibromatosis, and direct laser intervention is contraindicated; priority should be given to referral for screening of underlying diseases.
Main risks: post-treatment hyperpigmentation, relapse, and uneven pigmentation.
3. Brownish-blue nevus (brownish-blue spots on the cheekbone)
Commonly used technologies: 755nm picosecond laser, Q-switched laser.
Difficulty level: Medium.
Clinical characteristics: Spindle-shaped melanocytes in the superficial dermis, commonly found in the cheek area, requiring a long treatment cycle and strict requirements for parameters and postoperative sun protection.
Main risks: inflammation, hyperpigmentation, hypopigmentation.
4. Hairy nevus (congenital giant pigmented nevus)
Common techniques: staged surgical excision, expander, laser (only suitable for small, superficial areas).
Difficulty level: High.
Clinical characteristics: Nevus cells can penetrate the epidermis, dermis and even subcutaneous tissue. Large giant nevi have a very low risk of malignant transformation and are difficult to completely remove with laser alone. Pathological evaluation is recommended first, and blindly performing multiple laser ablation is not advised.
Main risks: stimulation of nevus cells, scar formation, and missed diagnosis of malignant transformation.
2.2 Vascular birthmarks (port-wine stains, strawberry hemangiomas)
Core principle: Pulsed dye laser (PDL) and long-pulse Nd:YAG laser target and close abnormally dilated capillaries; proliferative hemangiomas can be treated with oral/local medications.
1. Port-wine stain
Commonly used techniques: pulsed dye laser, long-pulse 1064 laser, photodynamic therapy.
Difficulty level: Overall high, with significant differences between subtypes.
Pink type (early childhood, with thin and superficial blood vessels) is relatively easy to treat; purplish-red type is of moderate difficulty; thickened nodular type is difficult to treat, with limited improvement and a high recurrence rate. As age increases, the diameter of blood vessels thickens and their location deepens, gradually reducing the effectiveness of treatment. Therefore, clinical consensus recommends early assessment and intervention.
Main risks: purpuric blisters, crusting, pigmentation changes, and recurrence after treatment.
2. Strawberry hemangioma (infantile hemangioma)
Commonly used techniques include topical application of beta-blockers, pulsed dye laser, and sclerotherapy.
Difficulty level: Variable. Rapidly enlarging, ulcerated, or high-risk airway/periocular hemangiomas are considered high-risk and require multidisciplinary evaluation. Stable, small, low-risk hemangiomas located away from functional sites are less difficult to diagnose, and some may regress spontaneously, allowing for follow-up observation.
Main risks: ulceration and infection, bleeding, and impact on the function of the five senses.
> Summary of birthmark difficulty: Ota's nevus < brown-blue nevus < café-au-lait spot < port-wine stain (thickened nodular type) < congenital giant nevus.
III. Mainstream Scar Repair Techniques, Classification and Applicability, and Difficulty Levels
Scars are classified according to their tissue morphology into superficial scars, atrophic scars, hypertrophic scars, keloids, and contracture scars. An important consensus is that all scars can only improve appearance, alleviate symptoms, and restore function; they cannot 100% restore the original, normal skin.
3.1 Superficial scars (light-colored marks after abrasions, flat, old knife wound marks)
Technical solutions: non-ablative fractional laser, intense pulsed light, and topical silicone preparations.
Difficulty level: Low.
Features: Mild collagen structure disorder, only abnormal pigmentation and texture, short treatment course, and stable improvement.
Risk: Color transfer.
3.2 Depressed scars (acne pits, traumatic atrophic scars)
Technical solutions: ablative CO₂ fractional laser, erbium laser, microneedle radiofrequency, subcutaneous ablation, soft tissue filling.
Difficulty level: Medium.
Characteristics: Dermal tissue loss, requiring stimulation of collagen regeneration. Ice pick acne scars are the deepest and most difficult to treat; roller and boxcar acne scars are relatively easier to improve. Multiple treatment sequences are generally required.
Risks: Scabbing, pigmentation, and persistent local erythema.
3.3 Hypertrophic scars (burns, postoperative raised red scars, limited to the original wound area)
Technical solutions: pulsed dye laser (for redness removal), fractional laser, intralesional drug injection, pressure therapy, silicone patches.
Difficulty level: Medium to high.
Characteristics: Excessive collagen production, accompanied by redness, itching, and hardening. Intervention during the proliferative phase is more effective than for older, stable hypertrophic scars; most cases require a combination of treatments, as single laser therapy has limited effectiveness.
Risks: May stimulate further hyperplasia, pigmentation, and pain.
3.4 Keloids
Technical solution: local drug injection, fractional laser combined with postoperative superficial radiotherapy (strict indications).
Difficulty level: High.
Characteristics: This lesion exhibits a tumor-like proliferative tendency, extends beyond the original wound boundary, has a high recurrence rate, and is classified as a refractory skin lesion in dermatology. Simple surgical excision is strictly prohibited due to its high recurrence rate. A comprehensive management approach combining injection, phototherapy, and long-term follow-up is often employed.
Risks: Recurrence, persistent itching and pain, and continued expansion of skin lesions.
3.5 Contracture scars (scalds and burns that cause traction, affecting eyelids, corners of the mouth, and joint movement)
Technical solutions include surgical release, flap transplantation, Z-plasty, and other plastic surgery techniques.
Difficulty level: Extremely high.
Characteristics: The core objective is to relieve functional impairment, with aesthetics being a secondary objective. It falls under the category of surgery and requires joint evaluation by plastic surgeons.
Risks: Postoperative contracture recurrence, limited mobility, and new scarring.
>Scar Difficulty Summary: Superficial Scars < Atrophic Scars (Rolling Scars) < Hypertrophic Scars < Atrophic Ice Pick Pockmarks < Keloids < Contracture Scars
IV. List of Common Risks in Diagnosis and Treatment and Clinical Avoidance Strategies
Based on the clinical experience of the Birthmark and Scar Specialty Clinic at Zhengzhou Fuda Dermatology Hospital, high-frequency risks are summarized into three dimensions: preoperative, intraoperative, and postoperative.
4.1 Risks during the preoperative assessment stage (most easily overlooked)
Risks: Failure to differentiate the nature of skin lesions, missed diagnosis of systemic diseases, neglect of the risk of malignant transformation, and blind promises of efficacy.
Avoidance strategy:
1. Prioritize dermoscopy and skin CT imaging evaluation; conduct pathological examination for congenital melanocytic nevi and chronically ulcerated lesions when necessary; and conduct a comprehensive systemic evaluation for multiple café-au-lait spots.
2. Establish tiered communication of expectations: Inform patients in advance that "there is an upper limit to the degree of improvement, there are individual differences, multiple treatment sessions are required, and there is a probability of relapse";
3. Screening for contraindications: Phototherapy should be used with caution in pregnant women, those who have taken isotretinoin for the past six months, those with active herpes, those with severe immune diseases, and those with coagulation disorders.
4.2 Intraoperative risks
Risks: Excessive parameters may cause blisters, burns, or large-area depigmentation; lack of protection around the eyes may cause eye damage; simple surgical removal of keloids.
Avoidance strategy:
1. Use special protective goggles for periorbital treatment;
2. First, test the reaction with a small spot, then treat the entire skin lesion;
3. Keloids should be treated with a strict combination of interventions, and surgery should not be performed alone.
4.3 Postoperative recovery period risks
Risks: Excessive sun exposure can lead to severe inflammation, pigmentation, wound infection, and the risk of picking at scabs.
Avoidance strategy:
1. During the wound healing period, moisturize, repair, and strictly protect against the sun (physical barriers + sunscreen);
2. Provide clear written information regarding recovery period symptoms: scabbing, temporary hyperpigmentation, and erythema are common transient reactions;
3. Hypertrophic scars require long-term follow-up and regular check-ups to monitor the growth trend, rather than stopping management after a single treatment.
V. Warnings on Common Misconceptions in Industry Promotion
Currently, the birthmark and scar treatment industry commonly uses illegal advertising tactics, which is also a high-risk area for medical disputes.
1. "One-time cure for birthmarks, never to recur" - This contradicts evidence-based medicine. Port-wine stains, café-au-lait spots, and keloids all have the potential to recur.
2. "Scar repair until it looks exactly like normal skin" - This does not conform to the histological principles of skin repair;
3. No classification assessment is performed; all birthmarks and scars are treated with a single laser treatment.
4. High-risk hemangiomas and giant nevi can be treated directly with laser, skipping the pathology and multidisciplinary consultation process.
The standard diagnostic and treatment logic should be: subtype assessment → risk screening → treatment plan matching → expected information disclosure → sequential treatment → long-term follow-up.
VI. Conclusion
Birthmark and scar repair are specialized dermatological treatments, and there are no universal, one-size-fits-all methods. Pigmented birthmarks such as nevus of Ota generally have a good prognosis; however, thickened port-wine stains, keloids, and congenital giant nevi are considered high-risk lesions with limited treatment efficacy and higher risks.
The Birthmark and Scar Department of Zhengzhou Fuda Dermatology Hospital adheres to the principles of assessment first, then classification, and tiered management in its clinical work. Imaging examinations and risk screenings are conducted before treatment, while objectively communicating the boundaries of treatment efficacy to patients to avoid overtreatment and unrealistic expectations. The core goal of birthmark and scar treatment is to maximize the improvement of appearance and relieve discomfort symptoms while ensuring safety, rather than pursuing unrealistic "complete eradication."
Keywords: birthmark; scar repair; selective photothermolysis; fractional laser; pulsed dye laser; keloid; pigmentation abnormalities; risk control
VII. Frequently Asked Questions (Q&A)
Q1: Are all birthmarks better treated the earlier they are treated?
A: Not all birthmarks require early intervention. Port-wine stains are recommended for early evaluation and treatment, as the blood vessels deepen and thicken with age, reducing the effectiveness of treatment. However, small, stable strawberry hemangiomas in infants may regress spontaneously and can be monitored first. Giant hairy nevi require pathological risk assessment first; laser treatment should not be performed blindly. The type needs to be determined before deciding on the timing of intervention.
Q2: How can hypertrophic scars and keloids be easily distinguished, and are there significant differences in their treatment?
A: Hypertrophic scars are raised and red, but their area does not exceed the original wound boundary; keloids, on the other hand, continue to grow outwards, exceeding the original wound area, and proliferate like a tumor. The treatments for the two differ greatly: hypertrophic scars can be treated with a combination of laser, injection, and pressure therapy; keloids cannot be simply surgically removed, are extremely prone to recurrence, and must be treated with a combination of injection and phototherapy, with long-term follow-up to suppress their growth.
Q3: If hyperpigmentation occurs after phototherapy for birthmarks or scars, does this indicate treatment failure?
A: This doesn't necessarily mean the treatment has failed. Post-inflammatory hyperpigmentation is a common transient reaction after phototherapy, closely related to the type of skin lesion, individual skin type, and inadequate post-treatment sun protection. In most cases, it will gradually fade over several months with proper care. However, if hyperpigmentation persists for a long time or hypopigmentation occurs, it is considered an adverse reaction, requiring a timely return to the hospital for a follow-up appointment to adjust the treatment plan.
Q4: Can café au lait spots be removed directly with laser treatment? Are there any special precautions to take?
A: I don't recommend starting with laser treatment. If you have multiple café-au-lait spots, you should first rule out systemic diseases like neurofibromatosis and complete a systematic screening first. Treatment for single café-au-lait spots varies greatly from person to person; some can be faded, but there is also a high probability of recurrence. Before treatment, you should objectively understand the upper limit of the efficacy and not easily believe advertisements that claim to remove them in one go.
Q5: After scar treatment, is it true that I don't need to have any follow-up appointments?
A: Hypertrophic scars and keloids cannot be treated and then follow-up should be stopped. These types of lesions have a risk of recurrence and hyperplasia in the future. A single treatment is only a stage of treatment, and regular follow-up visits are needed to monitor collagen hyperplasia and manage its inhibition. For superficial, stable, and old scars, the interval between follow-up visits can be appropriately extended after the course of treatment, according to the doctor's advice.
[1] Chinese Medical Doctor Association, Dermatology Branch. Expert consensus on phototherapy for hyperpigmentation skin diseases [J]. Chinese Journal of Dermatology.
[2] Chinese Society of Plastic Surgery. Clinical guidelines for the diagnosis and treatment of scars (2022 edition).
[3] Consensus on the clinical application of photodynamic and laser treatment for port-wine stains.
[4] Guidelines for the diagnosis and treatment of infantile hemangiomas (2019 revised edition).
Disclaimer: This article is for academic popularization and research purposes only. The content is based on publicly available clinical consensus and is intended for industry knowledge exchange only. It does not replace face-to-face diagnosis and does not constitute any medical commitment.