Although there are many similarities between proliferative keloid scars and keloids, the differential diagnosis between the two is important for dermatologic surgeons because of the differences in mechanisms of occurrence and prognosis. Although the scar may appear bright red and itchy in the early stage, it usually atrophies and becomes darker or even skin-colored after 1 year of surgery, and the symptoms gradually diminish or disappear. Generally speaking, hyperplastic keloid scars are better treated. Keloid scars are more prevalent in blacks, Hispanics, and yellow Asians and are characterized by: (1) the cause is usually unknown, or there was a minor local injury or inflammatory reaction such as mosquito bites, folliculitis, acne, chicken pox, etc.; (2) they usually occur on the neck, back of the chest, and earlobes, and involve much more than the original injury; (3) the lesions continue to grow, and the surface of the lesions is often bright red; (4) itching and other symptoms are Itching and other symptoms are obvious. Overall, the recurrence rate of keloid treatment is high. Common measures used to treat hyperplastic keloids and keloids include [1-2]: intradermal corticosteroid injections, cryotherapy, laser treatment, surgical excision, radiation therapy, silicone film products, and topical medications such as imiquimod and mucopolysaccharide polysulfate. Other drugs that have been shown to be effective but are not widely used due to lack of evidence-based validation or limitations of the drugs themselves include: 5-Fu, bleomycin, retinoic acid, calcium channel blockers, mitomycin C, interferon-α2b, etc.
1.1 Intradermal corticosteroid injections: this is by far the most widely used treatment method, and the recurrence rate after treatment is statistically 50% [1]. In Europe and the United States, trimethoprim injection is most commonly used, and the concentration of 10-40 mg/ml is chosen according to the size of the lesion, which usually requires several local injections with an interval of 1 month. In China, due to the limitation of drug varieties, the most commonly used is a mixture of long- and short-acting betamethasone propionate. If the lesion area is large, appropriate amount of lidocaine can be added to dilute it, and the interval between injections is 4 weeks. Hormone injections help to soften the scar and reduce the symptoms. Possible side effects of hormone localization include tissue atrophy, hyperpigmentation or hypopigmentation, and capillary dilation. Since there is a certain amount of systemic absorption of hormone by local injection, this method is not suitable for larger scars and must be controlled in total.
1.2 Cryotherapy: It is believed that freezing can improve dermal collagen synthesis and normalize scar collagen. Cryotherapy is only suitable for smaller scars and overuse can cause delayed wound healing, pain and significant hyperpigmentation. Cryotherapy alone is more frequent than conventional cryotherapy when treating keloid scars, and can be performed once every few days. In recent years, cryotherapy before local injection of hormone is advocated, which can bring out the therapeutic effect of freezing on the one hand, and on the other hand, the tissue swelling caused by freezing facilitates hormone injection, infiltration and absorption.
1.3 Surgery: Surgery is only a means of shaping, it must be used in combination with other treatments, otherwise the recurrence rate is almost 100%, and the recurrence scar appears more serious. In other words, most treatments have some role in preventing scarring, and often have poor effect on hypertrophic mature scarring. Surgical excision of scarring can create opportunities for other treatments to prevent scarring, while the role of scarring can also be prevented through reduction sutures and fine skin buttressing. During surgery, attention should be paid to minimize the damage to the surgical cut edge, try not to use electrocutting and electrocoagulation equipment, and must stop bleeding thoroughly; pay attention to subcutaneous hypotonic suture when suturing, so as not to leave a dead cavity; skin alignment should be kept neatly turned out and not under tension. After surgery, follow-up treatment such as radiotherapy and local hormone injection can be chosen.
1.4 Radiotherapy: radiotherapy is a good partner of surgery and is usually implemented after surgery. In the past, superficial X-ray irradiation was often used. Linear gas pedal electron beam irradiation is easier to control the depth and intensity of irradiation than the former, so it has become the mainstream technique now. Studies have confirmed that radiotherapy should be administered within 24 h of surgery for about 5 consecutive sessions, with an average 5-year cure rate of 80% [1]. There are several points worth noting: (1) radiotherapy can cause local redness, swelling, pain and delayed closure, so postoperative care should be in place, and the removal of stitches should be delayed appropriately; (2) radiotherapy has a total dose limit, and for one lesion the dose of radiation for each treatment should be accumulated, and if the upper limit is reached no more radiotherapy can be given. Therefore, at present, it is not advocated to directly radiotherapy scar, and the limited radiotherapy dose should be used on the blade, i.e., to prevent scar formation after surgery, and the randomly wasted dose may cause lifelong regret to patients; ③The specific operation of medical personnel during radiotherapy, especially the placement of molds, will directly affect the efficacy, so the responsibility of operators must be strengthened. Although the effect of radiotherapy is relatively clear, some scholars have recently insisted that radiotherapy should not be implemented for benign masses.
1.5 Laser therapy: CO2 laser and argon laser cautery have been shown to have a 99% recurrence rate for scar treatment. Currently, 585 nm pulsed dye laser irradiation of the scar is considered to be effective [1] and is recommended to be used in conjunction with hormonal local sealants. Nd:YAG laser treatment has also been attempted [1], and although the preliminary findings are optimistic, further in-depth studies are needed.
1.6 Silicone film products: Topical silicone film is a noninvasive method of scar prevention, so it is currently widely used. It is believed that external application of silicone film helps to hydrate the skin tissue and can soften the formed scar, which can reduce inflammatory reactions such as redness, swelling, pain and itching, and thus play a role in preventing scarring. The use of silicone film products is generally required early after the injury, and is applied daily for more than 12 hours. Silicone film products need to be cleaned regularly, but they can be applied repeatedly until they lose their adhesion and then replaced with new ones. The efficacy of silicone film products varies widely in the literature, with the highest reaching 70% to 80% efficiency, and some studies suggesting that the mechanism of action of silicone film products is equivalent to sealing [1].
1.7 Other drugs 1.7.1 Imiquimod cream: It induces the production of several inflammatory factors. TNF-α is thought to inhibit fibroblast collagen synthesis, which may be the mechanism of topical imiquimod in the treatment of scarring. The current study concluded that topical application of this drug has some efficacy for 8 weeks, but the follow-up time of the data is relatively short and the drug has some local irritant effect.
1.7.2 5-Fu: It has the effect of inhibiting DNA synthesis. Compared with its toxic side effects, the therapeutic effect of this drug is not outstanding, so it is not widely used. The drug is prone to ulceration and hyperpigmentation when applied topically, and local injection has the potential to trigger anemia, thrombocytopenia and leukopenia.
1.7.3 Bleomycin: This drug is a chemotherapeutic agent with multiple targets of action at the cellular level. This drug is rarely used clinically due to consideration of toxic side effects.
1.7.4 Interferon alpha-2b: It regulates the activity of growth factors and has anti-proliferative and anti-fibrotic effects. Previous attempts have been made to treat scarring with topical interferon creams and local injections of interferon, but the results are not very satisfactory.
1.7.5 Mucopolysaccharide benzoate and related heparin sodium and hyaluronic acid mixture: The core components of this class of drugs are heparin sodium and hyaluronic acid, which can exert the effects of heparin sodium and hyaluronic acid within the skin level after topical application through transdermal absorption. Sodium heparin has the effect of promoting blood circulation and increasing metabolism, while hyaluronic acid is believed to play an important role in the early stage of wound healing, so theoretically the drug has a certain role in preventing the occurrence of scarring. Since this drug has fewer side effects when applied topically and the dosage form helps to play a sealing role, it is now widely used in clinical practice. It is usually applied topically twice a day right after the stitches are removed, and should be rubbed repeatedly to promote absorption when applied for more than six months continuously.
There are many treatments for hyperplastic keloids and keloid scars, but none of them has been recognized as the gold standard of treatment, so they are usually applied clinically in combination with multiple methods. The patient’s condition, needs, and objective status should be fully evaluated before choosing a treatment option. If the patient is not effective, surgery and radiotherapy can be considered. Mucopolysaccharide, interferon gel and other drugs. In conclusion, the treatment of hyperplastic keloids and keloid scars is a challenge for the dermatologist and requires the close cooperation of the patient.