Hur Hoon, M.D., Ph.D.

Choice Dermatology Clinic, Pyeongchon, Korea

 

Discussion

Caféau laitspot(CALS), partial unilateral lentiginosis(PUL) and Becker’s nevus(BN) are recalcitrantpigmentary skin diseases without malignant potential^1,2,3,4.

In solitary CALS, PUL and BN,the expression of endothelin-1 is increased in the keratinocytes and the expression of stem cell factor(SCF) is increased in the fibroblasts compared to those of normal skins. The increased expression of endothelin-1 andSCF activates the melanocytes and increases melanin synthesis in the melanosomes, therefore causing solitary CALS, PUL and BN.^9,10,11,12.However, basic fibroblast growth factor(bFGF) that may provoke melasmaand PIH^9,10,11,12. Given that bFGF in the keratinocytes of CALS, PUL and BN is not increased, bFGF may not cause CALS, PUL and BN^9,10,11,12.

For a lot of years electromagnetic radiation(EMR) from Lasers, flesh lamps and other EMR sources has been used to treat the pigmentary skin diseases such as CALS, PUL and BN. EMR, targeting the melanin chromophore well described the theory of selective photothermolysis(SPTL)⁶. The treatments with Many Lasers or Intense Pulse Light(IPL) were performed but the traditional Laser treatments were unsatisfactory for CALS, PUL and BN.

Because the common side effects such as PIH, scars and recurrences occurred after traditional Lasertreatment^6,7,8.

 

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There are possible four reasons of failure when treating CALS,PUL and BN with traditional Laser treatment. First, 532nm of Q- SwithchedNd:YAGLaser, 694nm of Ruby Laser, 755nm of alexandrite, and 515-755nm of IPL absorb much more melanin compared to 1064nm of Q- SwithchedNd:YAGLaser. Thus, fluence that destroys epidermal melanocytes injuries the surrounding keratinocytes, and the damaged keratinocytes secrete endothelin-1, MSH,ACTH,prostaglandin(PGE2,PGF2  and nitric oxide. These cytokines activate melanocytes and increase melanin synthesis in the melanosomes, therefore causing PIH and worsening CALS,PUL and BN^9,10,11,12.

Second, the keratinocytes secrete urokinase type plasminogen activator(U-type PA) that converts plasminogen into plasmin. This plasmin stimulates the keratinocytes, which secrete bFGF that activates the melanocytes and increase melanin synthesis in the melanosomes, therefore causing PIH and worsening CALS,PUL and BN. The authors believes that bFGF, a major cytokine, causes PIH and melasma because tranexamicacid(500mg/day for 90days), which suppresses U-type PA and plasmin, improvesmelasma and PIH^9,10,11,12.

Third, as the traditional Lasertreatment causes petechiae and crusts, irradiated fluence may damage fibroblasts, mast cells, lymphocytes, macrophages, and vascular endotheliums. Then, fibroblasts mainly secrete SCF and mast cells, in which the activation of arachidonicmetabolites occurs, secrete histamine. The arachidonic metabolites and histaminecause inflammatory reaction that activates melanocytes and increasesmelanin synthesis in the melanosomes, eventually causing PIH and worsening CALS,PUL and BN^9,10,11,12.

Lastly, free radical oxygen and peroxide from the keratinocytes also activates melanocytes and increase melanin synthesis in the melanosomes, eventually causing PIH and worsening CALS, PUL and BN^9,10,11,12. To solve the side effects such as PIH and worsening CALS,PUL and BN of the traditional Lasertreatment, the authors devised Dr. HurHoon's Golden Parameter Therapy(GPT)⁵. The authors would like to name this therapy “Golden Parameter Therapy” because the authors believes that it can improve various skindiseases(Table 1)⁵. The Golden Parameter with a 1064nm Q-switched Nd:YAGLasermay destroy melanocytes without keratinocyte damage, and the products of damaged melanocytes will be removed through transepidermal elimination^5,10,11,12. Then, basement membrane breaks down and epidermal melanocytes secrete melanin into the upper dermis. Thus, after phagocytizing this melanin, dermal melanophage is eliminated through dermal lymphatics^5,10,11,12. By apoptotic melanocytic cell death and homeostasis, normal melanocytes in outer root sheath of hair migrate to basal layer and abnormal melanocytes are displaced into normal melanocytes in the basal layer^5,10,11,12. It is the authors’ theory that this Laser treatment can be performed complete clearance of the CALS PUL and BN without side effects or recurrences⁵. 

 

-To be continued-