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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_813_Библиотеки_им_академика_М_И_Перельмана.pdf
88 Part IV&Skin Care
REFERENCE
1. Montagna W, Prota G, Kenney JA Jr, eds. Black Skin Structure and Function. San Diego: Academic Press; 1993
HYPOPIGMENTATION
4. A 28-year-old woman is seen in clinic for a concerning new patch of depigmented skin on the left cheek. The
lesion is flat, 5 cm in diameter, and sharply demarcated. Other than autoimmune thyroid disease requiring
her to take exogenous thyroid hormone, she is healthy. Which of the following is the most appropriate
response to the patient regarding management of this lesion?
E. Manage with phototherapy, immunomodulators, and topical steroids.
Although the underlying condition cannot be totally cured, the lesion can be managed with phototherapy,
immunomodulators, and topical steroids. Given the characteristics of the lesion (flat, well-demarcated,
depigmented) and the patient's previous history of autoimmune disease, a clinical diagnosis of vitiligo
can reliably be made without surgical measures such as biopsy or excision. Telling the patient that no interventions can be taken is not appropriate; phototherapy, immunomodulators, and topical steroids can all be
used to manage vitiligo lesions.
1
REFERENCE
1. Baldini E, Odorisio T, Sorrenti S, et al. Vitiligo and autoimmune thyroid disorders. Front Endocrinol (Lausanne)
2017;8:290
PIGMENTATION INHIBITORS
5. Which of the following pigmentation inhibitors acts by suppressing the formation of melanocytes?
C. Lactic acid.
Lactic acid acts by suppressing the formation of melanocytes. Hydroquinone inhibits tyrosinase, the
enzyme responsible for production of melanin, via inhibition of DNA and RNA synthesis. Kojic acid
likewise inhibits tyrosinase, but via a different mechanism: it chelates tyrosinase-bound copper,
inactivating the enzyme (Table 15.2 ).
1
Table 15.2 Commonly Used Pigmentation Inhibitors
Inhibitor Mechanism of Action
Hydroquinone Inhibits tyrosinase by inhibiting DNA and RNA synthesis
Kojic acid Chelates copper bound to tyrosinase rendering it inactive
Azelaic acid Naturally derived from grain products and by oxygenation of oleic acid Cytotoxic to melanocytes
Lactic acid Suppresses formation of melanocytes
Retinoids Inhibits tyrosinase activity
Arbutin Found naturally in cranberries
Inhibits melanosome maturation
Less irritating than hydroquinone
REFERENCE
1. Taylor SC. Utilizing combination therapy for ethnic skin. Cutis 2007;80(1 Suppl):15
ACNE
6. Which of the following is the most effective strategy for preventing postinflammatory hyperpigmentation in
darker-skinned individuals?
E. Immediate treatment with topical clindamycin, topical retinoid, and benzoyl peroxide.
Postinflammatory hyperpigmentation is a major sequela of acne in darker-skinned individuals. For this
reason, the primary goal of acne treatment in this population is prevention of this phenomenon. Early
intervention is necessary to achieve this goal, rendering watchful waiting an inappropriate course of
action. Additionally, monotherapy often proves ineffective. Studies have shown that the most effective
therapy involves prompt treatment with clindamycin, topical retinoid, and benzoyl peroxide.
1
Chapter 15&Ethnic Skin Care 89
REFERENCE
1. Taylor SC. Utilizing combination therapy for ethnic skin. Cutis 2007;80(1 Suppl):15
SUNSCREEN
7. A female patient of Northern European heritage who has a history of rosacea would like to know which is the
most appropriate sunscreen she should use and why?
D. An inorganic sunscreen is most appropriate, as it is less likely to exacerbate preexisting skin condi-
tions such as rosacea.
Sunscreen use is important to prevent skin cancer in all patients, including darker-skinned individuals,
regardless of skin conditions such as rosacea. The advantage of organic sunscreens is that they do not
cause the skin whitening that is seen in inorganic sunscreens such as titanium dioxide and zinc dioxide.
The mechanism of action of organic sunscreens involves absorption of solar radiation, which produces
heat. Unfortunately, heat can trigger various skin conditions, particularly rosacea. For this reason, an
inorganic sunscreen is most appropriate for patients with rosacea.
1
REFERENCE
1. Draelos ZD. Cosmeceuticals for rosacea. Clin Dermatol 2017;35(2):213–217
HAIR REMOVERS
8. Which of the following is true regarding use of chemical depilatories?
C. Chemical depilatories work by degrading disulfide bonds in the hair shaft.
Chemical depilatories are an alternative method of hair removal to shaving, which function by degrading
disulfide bonds in the hair shaft , causing swelling within the hair shaft. Importantly, this swelling can
cause irritation that can lead to postinflammatory hyperpigmentation. Regardless, the use of chemical
depilatories remains higher in the black population due to higher incidence of pseudofolliculitis barbae
after shaving. The most common active ingredients in chemical depilatories are calcium thioglycolate and
sodium thioglycolate—however, patients with coarser hair find that stronger ingredients are needed to
achieve hair removal. Stronger ingredients for use in patients with coarse hair include strontium sulfide,
barium sulfide, potassium hydroxide, and sodium hydroxide.
1
REFERENCE
1. Taylor SC. Utilizing combination therapy for ethnic skin. Cutis 2007;80(1 Suppl):15
PART V
Noninvasive and Minimally Invasive
Therapy
16. Basics of Laser Therapy
Ara A. Salibian
See Essentials of Aesthetic Surger y, pp. 205–211
PHYSICS OF LASERS
1. Which of the following characteristics of a laser determines its target chromophore?
A. Wavelength.
B. Spot size.
C. Pulse duration.
D. Beam shape.
E. Fluence.
MAJOR TYPES OF LASERS
2. What is the target chromophore for ablative CO2or erbium:YAG lasers?
A. Oxyhemoglobin.
B. Melanin.
C. Collagen.
D. Water.
E. Fat.
INDICATIONS AND CONTRAINDICATIONS
3. Which of the following factors is a contraindication to facial laser treatment?
A. Moderate perioral rhytides.
B. Mild acne scarring.
C. Facial tattoo with iron oxide.
D. Solar lentigines.
E. Erythematous hypertrophic scar.
PREOPERATIVE EVALUATION
4. A patient who sometimes burns but usually tans uniformly is designated as which skin type in Fitzpatrick
classification?
A. I.
B. II.
C. III.
D. IV.
E. V.
PREOPERATIVE EVALUATION
5. Which of the following medications should not be given to patients prior to facial laser resurfacing?
A. Hydroquinone.
B. Vitamin C.
C. Trenitoin.
D. Isotretinoin.
E. Acyclovir.
PREOPERATIVE EVALUATION
6. Which of the following viral infections is most common after facial laser resurfacing?
A. Cytomegalovirus.
B. Varicella-zoster.
94 Part V&Noninvasive and Minimally Invasive Therapy
C. Herpes simplex virus.
D. Human immunodeficiency virus.
E. Human papilloma virus.
INFORMED CONSENT
7. Which of the following is true for facial resurfacing with lasers?
A. Have low efficacy with poor outcomes.
B. Lower risk for hyperpigmentation in patients with darker skin tone.
C. Multiple treatments are almost always needed.
D. Do not treat tattoos.
E. Are ineffective for vascular lesions.
Chapter 16&Basics of Laser Therapy 95
Answers
PHYSICS OF LASERS
1. Which of the following characteristics of a laser determines its target chromophore?
A. Wavelength.
Lasers generate in phase, monochromatic and coherent light that causes tissue injury based on wavelengthspecific light absorption by a target chromophore. Each wavelength has an absorption spectrum that
identifies the optimal targets. The absorption spectrum of oxyhemoglobin is at lower wavelengths, with
melanin and finally water having higher wavelengths of optimal absorption. The principle is used in selective
photothermolysis to minimize heat damage to surrounding tissues by targeting specific chromophores.
REFERENCE
1. Atiyeh BS, Dibo SA. Nonsurgical non-ablative treatment of aging skin: radiofrequency technologies between
aggressive marketing and evidence-based efficacy. Aesth Plast Surg 2009;33:283
MAJOR TYPES OF LASERS
2. What is the target chromophore for ablative CO2or erbium:YAG lasers?
D. Water.
High-energy ablative lasers target water in living cells, damaging the epidermis and parts of the dermis.
Ablative lasers produce an open wound and have a higher risk of scarring and pigmentation than
nonablative lasers depending on the depth of tissue injury.
CO
lasers (10,600 nm) and the erbium:YAG laser (2,940 nm) are the most common type of ablative lasers
2
and can effectivel y treat rhytides, finer acne scars, and sun damage. Erbium lasers are absorbed more readily
by water than CO
faster healing and less risk of hypopigmentation but also less collagen contraction than CO2lasers.
lasers, penetrating less deeply and causing less photomechanical injury. This results in
2
1
1
REFERENCE
1. Brightman LA, Brauer JA, Anolik R, et al. Ablative and fractional ablative lasers. Dermatol Clin 2009;27:479
INDICATIONS AND CONTRAINDICATIONS
3. Which of the following factors is a contraindication to facial laser treatment?
C. Facial tattoo with iron oxide.
Several types of tattoos are amenable to laser treatment, particularly with different q-switched lasers. These
lasers lyse cells that contain tattoo pigments, which are then phagocytosed by surrounding immune cells.
Although effective, multiple treatments are often needed, and side effects can include depigmentation.
However, laser treatment of tattoos with iron oxide in the ink should be avoided. Lasers will convert the
ferrous oxide into ferric oxide and can permanently darken the skin.
1
REFERENCE
1. Alexiades-Armenakas M. Laser-mediated photodynamic therapy. Clin Dermatol 2006;24:16
PREOPERATIVE EVALUATION
4. A patient who sometimes burns but usually tans uniformly is designated as which skin type in Fitzpatrick
classification?
C. III.
The Fitzpatrick skin type classification stratifies patients based on their propensity to have pigmentary
changes after laser resurfacing (Table 16.1). Fitzpatrick I patients have pale white skin and freckles and
will always burn and never tan with sun exposure. Fitzpatrick VI patients, on the other hand, have black
skin, never burn, and tan very easily. Fitzpatrick III patients have creamy white skin, will sometimes
burn, and tan relatively uniformly. Fitzpatrick skin types I–III are the ideal candidates for laser resurfacing, whereas as those with IV–VI skin types are at a higher risk of transient hyperpigmentation and
96 Part V&Noninvasive and Minimally Invasive Therapy
long-term hypopigmentation. Patients with lighter skin, however, have a higher risk of prolonged postoperative erythema. It is important to discuss these risks with patients prior to treatment to set appropriate
patient expectations with regards to outcomes and side effects.
Table 16.1 Fitzpatrick Skin Type Classification
Skin Type Characteristics Sun Exposure History
1 Pale white, freckles, blue eyes, blond or red hair Always burns, never tans
II Fair white, blue/green/hazel eyes, blond or red hair Usually burns, tans minimally
III Cream white, any hair or eye color Sometimes burns, tans uniformly
IV Moderate brown (Mediterranean) Rarely burns, always tans well
V Dark brown (Middle Eastern) Rarely burns, tans easily
VI Dark brown to black Never burns, tans easily
(Source: Data from Fitzpatrick TB. The validity and practicality of sun-reactive skin types I through VI. Arch
Dermatol 124:869, 1988.)
1
REFERENCE
1. Fitzpatrick RE, Williams B, Goldman MP. Preoperative anesthesia and postoperative considerations in laser
resurfacing. Semin Cutan Med Surg 1996;15:170
PREOPERATIVE EVALUATION
5. Which of the following medications should not be given to patients prior to facial laser resurfacing?
D. Isotretinoin.
Laser resurfacing is contraindicated in patients taking isotretinoin (Accutane). This medication should be
stopped for at least 12 to 18 months prior to any laser procedures. Isotretinoin is a common medication
for cystic acne and impairs re-epithelialization, which is necessary to heal the tissue damage caused by
lasers. This impairment can subsequently lead to severe scarring after laser therapy. Hydroquinone is a
tyrosine kinase inhibitor and is used as a pretreatment of the skin to prevent hyperpigmentation.
Trenitoin (Retin-A) promotes re-epithelialization and is used as a pretreatment to promote healing after
laser therapy.
1,2,3
REFERENCES
1. Saedi N, Hamilton HK, Arndt KA, et al. How to prepare patients for ablative laser procedures. J Am Acad Dermatol
2013;69:e49
2. Mysore V, Mahadevappa OH, Barua S, et al. Standard guidelines of care: performing procedures in patients on or
recently administered with isotretinoin. J Cutan Aesthet Surg 2017;10(4):186–194
3. Ward PD, Baker SR. Long term results of carbon dioxide laser resurfacing of the face. Arch Facial Plast Surg
2008;10:238
PREOPERATIVE EVALUATION
6. Which of the following viral infections is most common after facial laser resurfacing?
C. Herpes simplex virus.
Patients undergoing facial resurfacing procedures are at a potential risk for herpes simplex virus (HSV)
infection. This risk is significantly higher in patients who have a history of HSV infection. All patients
should receive antiviral pretreatment for HSV which includes acyclovir 400 mg by mouth three times per
day, famciclovir 250 mg by mouth twice per day, or valacyclovir 500 mg by mouth twice per day for 1 to
3 days before treatment until re-epithelialization at 5 to 14 days.
1,2
REFERENCES
1. Fitzpatrick RE, Williams B, Goldman MP. Preoperative anesthesia and postoperative considerations in laser
resurfacing. Semin Cutan Med Surg 1996;15:170
Chapter 16&Basics of Laser Therapy 97
2. Manuskiatti W, Fitzpatrick RE, Goldman MP. Long term effectiveness and side effects of carbon dioxide laser
resurfacing for phyotoaged facial skin. J Am Acad Dermatol 1999;40:401
INFORMED CONSENT
7. Which of the following is true for facial resurfacing with lasers?
C. Multiple treatments are almost always needed.
Preoperative patient counseling and informed consent are key parts of any procedure, including laser
treatments. Lasers can be very effective tools for treating numerous skin lesions and dispigmentations
including vascular lesions, melanocytic pigmentations, lymphatic malformations, hair, angiokeratomas,
rhytides, scars, and tattoos. Depending on the depth of the lesion and the penetration of the laser,
multiple treatments are typically required to achieve the desired result, especially with nonablative
1,2
lasers.
REFERENCES
1. Alexiades Armenakas MR, Dover JS, Arndt KA. The spectrum of laser skin resurfacing: nonablative, fractional, and
ablative laser resurfacing. J Am Acad Dermatol 2008;58:719
2. Atiyeh BS, Dibo SA. Nonsurgical non-ablative treatment of aging skin: radiofrequency technologies between
aggressive marketing and evidence-based efficacy. Aesth Plast Surg 2009;33:283