Dermatology Advice ,Laser Surgical Treatments , Advanced Skin Care and Therapeutic Services
By Live Dr - Sat Nov 05, 11:55 pm
1、The skin is divided into three rather distinct layers. From the inside out, they are the subcutaneous tissue, the dermis, and the epidermis.
2、The epidermis is the most superficial of the three layers of the skin and averages in thickness about the width of the mark of a sharp pencil, or less than 1 mm. It contains several types of cells including keratinocytes, dendritic cells (melanocytes and Langerhans’ cells), and Merkel cells.
3、The keratinocytes, or keratin-forming cells, are by far the most common and develop into four identifiable layers of the epidermis. From inside out, they are as follows: Basal layer Living epidermis, Spinous layer, Granular layer, Cornified layer.
4 The three types of glandular appendages of the skin are the sebaceous glands, apocrine glands, and eccrine glands.
5 Descriptions of the basic lesions follow:
Macules are up to 1 cm and are circumscribed, flat discolorations of the skin. Examples: freckles, flat nevi.
Patches are larger than 1 cm and are circumscribed, flat discolorations of the skin. Examples: vitiligo, senile freckles, measles rash.
Papules are up to 1 cm and are circumscribed, elevated, superficial, solid lesions. Examples: elevated nevi, warts, lichen planus. A wheal is a type of papule that is
edematous and transitory (present less than 24 hours). Examples: Hives, sometimes insect bites.
Plaques are larger than 1 cm and are circumscribed, elevated, superficial, solid lesions. Examples: mycosis fungoides, lichen simplex chronicus.
Nodules range to 1 cm and are solid lesions with depth; they may be above, level with, or beneath the skin surface. Examples: nodular secondary or tertiary syphilis,
basal cell cancers, xanthomas.
Tumors are larger than 1 cm and are solid lesions with depth; they may be above, level with, or beneath the skin surface. Examples: tumor stage of mycosis
fungoides, larger basal cell cancers.
Vesicles range to 1 cm and are circumscribed elevations of the skin containing serous fluid. Examples: early chickenpox, zoster, contact dermatitis.
Bullae are larger than 1 cm and are circumscribed elevations containing serous fluid. Examples: pemphigus, second-degree burns.
Pustules vary in size and are circumscribed elevations of the skin containing purulent fluid. Examples: acne, impetigo.
Petechiae range to 1 cm and are circumscribed deposits of blood or blood pigments. Examples: thrombocytopenia and drug eruptions.
Purpura is a larger than 1 cm circumscribed deposit of blood or blood pigment in the skin. Examples: senile purpura and vasculitis.
Secondary lesions include the following:
Scales are shedding, dead epidermal cells that may be dry or greasy. Examples: dandruff (greasy), psoriasis (dry).
Crusts are variously colored masses of skin exudates. Examples: impetigo, infected dermatitis.
Excoriations are abrasions of the skin, usually superficial and traumatic. Examples: scratched insect bites, scabies.
Fissures are linear breaks in the skin, sharply defined with abrupt walls. Examples: congenital syphilis, athlete’s foot.
Ulcers are irregularly sized and shaped excavations in the skin extending into the dermis or deeper. Examples: stasis ulcers of legs, tertiary syphilis.
Scars are formations of connective tissue replacing tissue lost through injury or disease.
Keloids are hypertrophic scars beyond the borders of the original injury.
Lichenification is a diffuse area of thickening and scaling with resultant increase in the skin lines and markings.
6 Epidermal keratinocytes adhere to each other by desmosomes and structures such as adherens junctions, gap junctions and tight junctions.
7 Herpes zoster usually start with a burning pain, soon followed by erythema and grouped, sometimes bloodfilled, vesicles scattered over a dermatome.
8 Basement membrane zone：
The epidermal basement membrane zone, which lies immediately under the epidermis, stains by periodic acid Schiff (PAS) under the light microscope. The complicated structure of the basal membrane includes the lamina densa (LD) and the lamina lucida (LL), which are observed by electron microscopy.
9 Turnover time：
The period between the production of daughter epidermal cells and their exfoliation from the outer surface of the epidermis is called the turnover time, which is approximately 28 days in normal skin.
10 Scratch test：
The scratch test is a simple test to detect an immediate allergen(type I allergy). The flexor surface of the forearm is scratched with a needle or a needle-like tool without drawing blood, and one drop of antigen solution is applied to the forearm (Fig. 5.7).
If the patient is allergic to the allergen, reddening or swelling is produced on the spot. The diameter of the reddening or swelling along the minor axis is measured 15 to 20 minutes after application for identification of the allergy.
11 Nikolsky phenomenon：
In Nikolsky phenomenon, although the skin appears normal,blistering is produced by rubbing. The result is positive in pemphigus, epidermolysis bullosa, staphylococcal scalded-skin syndrome(SSSS), and toxic epidermal necrolysis (TEN) type drug eruptions.
12 Köbner phenomenon：
From stimuli such as rubbing or sunlight, a lesion is produced in normal skin; this is called the Köbner phenomenon, which is seen in psoriasis and lichen planus.
13 Auspitz phenomenon：
Auspitz phenomenon is the occurrence of small droplets of blood in skin. In psoriasis, when scales exfoliate, petechia is quickly produced . However, the patient may also test positive for Auspitz phenomenon in cases of eczema; it is not necessarily specific to psoriasis.
14 Subacute eczema：
Subacute eczema has a severity between that of acute and that of chronic. Such eczema is accompanied by erythema and edema, and it is slightly lichenoid. Mild edema is produced in the epidermis.
Urticaria is transitory localized erythema or wheals accompanied by itching.
Acute urticaria occurs in episodes shorter than 6 weeks;
chronic urticaria occurs in episodes of 6 weeks or longer.
Vascular permeability increases. Edema forms in the dermal upper layer.
In factitious urticaria, dermographism is positive.Oral antihistamines are the first-line treatment.
16 Types and indications of Topical Dermatologic Medications
WET DRESSINGS OR SOAKS
Indications: Oozing, vesicular skin conditions
Indications: Intertrigo, diaper dermatitis
Indication: Widespread, mildly oozing, inflamed dermatoses
OILS AND EMULSIONS
Indications: Acute and subacute eczematous eruptions or Winter itch, dry skin, atopic eczema
TINCTURES AND AQUEOUS SOLUTIONS
Indication: General antisepsis and drying
Indication: Localized crusted or scaly dermatoses
CREAMS AND OINTMENTS
1. Water-washable cream bases: treating intertriginous and hairy areas.
2. Ointment bases: alleviating dryness, removing scales, and enables the medicaments to penetrate the skin lesions.
17 Classification of drug eruptions by characteristic skin features
Toxic epidermal necrolysis
18 Pemphigus vulgaris
Acantholytic blisters form immediately above epidermal basal cells.The disease is caused by autoantibodies against desmoglein 3, which is a desmosomal adhesion factor in keratinocytes.
The pathogenesis involves anti-desmoglein antibodies. When there is the involvement of autoantibodies against desmoglein 1, pemphigus vulgaris becomes systemic. When anti-desmoglein 3 antibodies are exclusively involved, an oral mucosa type of the disease develops. The disease most frequently occurs in the middle-aged and elderly. It tends to manifest as oral enanthema. Nikolsky’s sign is positive.Oral steroids and immunosuppressants are the first-line treatment.
19 Clinical features of Bullous pemphigoid
Bullous Pemphigoid is a chronic, usually itchy, blistering disease,mainly affecting the elderly. The tense bullae can arise from normal skin but usually do so from urticarial plaques (Fig. 9.6). The flexures are often affected; the mucous membranes usually are not. The Nikolsky test is negative.
20 Types of psoriasis
1) Psoriasis vulgaris
Rose pink papules appear and extend to coalesce gradually into sharply circumscribed erythematous plaques with thick silvery scales on the surface. The eruptions are usually asymptomatic; however, itching is present in some cases. Areas that are subjected to external stimulation, such as the elbows, patellae, scalp and buttocks are most commonly involved. The disorder may also occur in the intertriginous areas of obese people.
2) Guttate psoriasis
Multiple keratotic erythema of up to 1 cm in diameter occurs on the trunk and proximal sides of the extremities with a relatively acute course. Individual eruptions are the same as those of psoriasis vulgaris. It is often seen in children. Streptococcal infection or drugs can be the causative factors.
3) Pustular psoriasis
Pustules are the main clinical feature. The disorder is subdivided into a generalized type and a localized type. In the generalized type, fever, systemic fatigue and bodily
chills accompany erythema on which multiple sterile pustules occur and coalesce. The pustules rupture spontaneously to form erosions. Exudative fluid may cause hypoproteinemia, leading to marked systemic aggravation in some cases. It may occur in the course of psoriasis vulgaris, or it may develop suddenly without any history of psoriasis.
4) Psoriatic erythroderma
Psoriatic skin lesions appear all over the body and become erythroderma.Proteins are consumed in large amounts in the lesions. The horny cell layer forms incompletely, bringing hypoproteinemia, dehydration and electrolyte abnormality.
5) Psoriatic arthritis
Arthritis symptoms may accompany psoriasis. The majority of cases are the peripheral type, which affects distal interphalangeal (DIP) joints. There is a type in which vertebra and sacroilitis are involved. Arthritis proceeds without psoriatic skin lesions in many cases. There is association with the HLA-Cw6 gene.
21 Bowen’s disease
It is a squamous cell carcinoma in situ. Highly atypical cells proliferate in all epidermal layers.
It presents as a sharply-margined plaque, ranging from reddish brown to blackish brown, with a diameter of 1 cm to 10 cm. Multiple lesions may be induced by chronic arsenic poisoning.
It is pathologically characterized by individual cell keratinization and cell clumping.Surgical removal and cryotherapy are the main treatments.
22 Clinical characteristics of melanoma (ABCDE).
Whenever a blackish-brown lesion is found, melanoma should be suspected.
B Borderline irregularity
C Color variegation
D Diameter enlargement (over 6 mm)
E Elevation of surface
23 Cutaneous symptoms of AIDS
The symptoms of AIDS are listed below. A decreased CD4+T cell count is associated with AIDS.
In Japan, homosexual males are most commonly affected. Multicentric nodules ranging from reddish purple to blackish brown occur most frequently. See Chapter 22 for details.
Mucocutaneous infectious disease
Candidiasis occurs in the oral cavity in all cases of AIDS; it has diagnostic value. Herpes simplex and herpes zoster are easily caused and tend to become generalized and severe. Multiple molluscum contagiosum appears on the face. Verruca vulgaris, cryptococcus, tinea and impetigo also occur and become intractable, displaying atypical clinical features in many cases. Viral infection such as in herpes zoster may recur
Seborrheic dermatitis, psoriasis vulgaris and eosinophilic pustular folliculitis often occur. Drug eruptions are induced by drugs that are taken for other diseases, including for pneumocystis carinii pneumonia.
24 Secondary syphilis
The period from the third month (to the third year) after infection is secondary syphilis. The Treponema pallidum organisms that have proliferated in the regional lymph node at primary syphilis disseminate hematogenously to the whole body, leading to various asymptomatic eruptions. Antibody titer becomes highest at this stage and decreases thereafter. The eruptions recur and disappear repeatedly for several years. Although eruptions first occur symmetrically on the whole body, they gradually become localized asymmetrically.
The main symptoms of the secondary syphilis are the following.