Cryotherapy is believed to induce vascular damage that may lead to anoxia and ultimate tissue necrosis80. Success rates of studies using contact or spray cryosurgery with liquid nitrogen vary between 32% and 74% after two or more sessions with higher response rates of hypertrophic scars compared to keloids18,81,82. A delay of approximately 3–4 weeks between sessions is usually required for postoperative healing, and commonly occurring side-effects include permanent hypo- and hyperpigmentation, blistering, and postoperative pain82,83. The intralesional needle cryoprobe method has recently been assessed in the treatment of hypertrophic scars and keloids84, demonstrating increased efficacy compared with that obtained with contact/spray probes and shorter re-epithelialisation periods84. The probe, which is inserted into the hypertrophic scar or keloid, is connected to a canister of liquid nitrogen, which causes the cryoneedle to freeze, thereby freezing the scar tissue from the inside out. Scar volume reduction of 70% for ear keloids and 60% for keloids on the upper back, shoulder and chest were achieved following a single cryo-session, as demonstrated in a recent study84.

Laser therapy

Since their introduction for keloids in the mid-1980s85, more lasers with different wavelengths have been studied — with varying degrees of success. Until today, the most encouraging results have been obtained with the 585 nm pulsed-dye laser (PDL), which has been recognised as a promising therapeutic option for the treatment of younger hypertrophic scars and keloids in a milestone study by Alster et al86. By causing local ischaemia through destroyed blood vessels, 585 nm PDL therapy is believed to induce neocollagenesis, collagen fibre heating with dissociation of disulfide bonds and subsequent collagen fibre realignment, decreased fibroblast proliferation, as well as release of histamine or other factors that influence fibroblast activity87–89. Non-overlapping laser pulses at fluences ranging from 6 to 7.5 J/cm2 (7 mm spot) or from 4.5 to 5.5 J/cm2 (10 mm spot) have been recommended for the treatment of hypertrophic scars and keloids90. Multiple treatments may be necessary to successfully improve scar resolution, including scar colour, height, pliability, and texture86. However, these results could not be reproduced in a number of subsequent studies91; in particular, the results in some case-control studies did not differ from the untreated control groups after longer follow-up observation periods92, 93.

Therefore, owing to the lack of untreated controls, too small case numbers, too short follow-up periods, lack of differentiation between hypertrophic scars and keloids, or lack of information on the age and activity of the scars, the majority of published studies do not possess sufficient evidence94. Adverse events include purpura, normally persisting for 7–14 days. Depending on the energy density used and the pigmentation of the skin, vesicles and crusts may occur. Longer persisting hyperpigmentation occurs particularly in darker skin types and is less frequent with the use of a 595 nm wavelength than 585 nm23. Occasionally, reactivation of younger keloids is observed, as experienced in the authors’ daily practice and by others95.

Figure 5 Commonly observed side-effects with intralesional steroids, such as (left) dermal atrophy and (right) telangiectasia

Figure 5 Commonly observed side-effects with intralesional steroids, such as (left) dermal atrophy and (right) telangiectasia

Based on the German Guidelines for the therapy of excessive scarring, PDL treatment can be recommended for the reduction of erythema (e.g. in fresh, highly vascularised, red scars) and can also be considered to alleviate severe pruritus23. Treatment with CO2 or Er : YAG lasers may be recommended for the ablation of inactive hypertrophic scars. The use of a CO2 laser for the removal of keloids as monotherapy, however, should be avoided owing to recurrence rates similar to those of surgical monotherapy for keloids23. Owing to a lack of controlled studies, no statement can yet be made on the use of fractional CO2 lasers in hypertrophic scars23.

Surgical approach

Surgical excision used to be the traditional treatment for keloids and hypertrophic scars96. To date, however, the authors are aware of the great recurrence rates (45–100%) of keloids after excision without adjuvant therapy such as post-excisional corticosteroid injections, 5-fluorouracil, or radiation18, and should therefore be considered with immense caution. Also, excision of a keloid automatically results in a longer scar than the original and recurrence in this new area of trauma may lead to an even larger keloid97, 98. Surgical repair (core excision with low tension wound closure, or shave excision) of earlobe keloids with post-surgery corticosteroid injections, postoperative pressure (pressure earrings), or application of imiquimod 5% cream or cryotherapy on the incision site usually provide good cosmetic results99.

Figure 6 Ulceration after injection of 5FU

Figure 6 Ulceration after injection of 5FU

With regard to hypertrophic scars, the timing of surgical treatment is an important consideration in the treatment protocol of scar revision strategy. Hypertrophic scars mature over at least a 1-year period, and can show decrease of contractures, flattening, softening, and re-pigmentation without any physical manipulation36. Therefore, surgical excision may not be needed, even though post-excisional recurrence rates of the original hypertrophic scar are usually low5, 100.


Superficial X-rays, electron beam and low- or high-dose-rate brachytherapy have been used in scar reduction protocols primarily as an adjunct to surgical removal of keloids with good results101. Radiation is thought to mediate its effects on keloids through inhibition of neovascular buds and proliferating fibroblasts, resulting in a decreased amount of collagen produced36. Electron beam irradiation is usually started 24–48 hours after keloid excision and the total dose is limited to 40 Gy over several administrations in order to prevent side-effects such as hypo- and hyperpigmentation, erythema, telangiectasia, and atrophy102. However, since radiation represents a potential risk with regard to carcinogenesis, particularly in areas such as the breast or thyroid, its use should be used with caution83,100.