CHAPTER 5
ECZEMA, ATOPIC DERMATITIS AND
OTHER PAPULOSQUAMOUS DISEASES
I. Atopic Dermatitis（アトピー性皮膚炎）
・ Atopic dermatitis is a chronic, pruritic inflammation of the epidermis and dermis, often occurring in association with a personal or family history of allergic disease (allergic rhinitis, asthma, hay fever, or atopic dermatitis).
・ The etiology is unknown, but there appears to be a genetic predisposition that can be exacerbated by numerous factors, including food allergy, skin infections, irritating clothes or chemicals, and emotions.
・ Lichenification is the clinical hallmark of chronic atopic dermatitis.
A. Diagnostic Criteria for Atopic Dermatitis
1. Pruritus
2. Typical morphology and distribution
Flexural lichenification in adults and older children
Facial and extensor papulovesicles in infancy
3. Chronic-relapsing course
4. Personal or family history of atopic disease
B. Age Incidence
1. Atopic dermatitis is predominantly a disease of childhood, with 5% of children affected.
2. Usually starts after 2 months of age, and by 5 years of age 90% of the patients who will develop atopic dermatitis have manifested their disease.
3. Adult onset patients are uncommon, but recently increasing.
C. Distribution
1. The morphology and distribution of atopic dermatitis are age-dependent.
2. Infantile atopic dermatitis is characterized by acute to subacute eczema with papules, vesicles, oozing, and crusting. lt is distributed over the head, the diaper area, and the extensor surfaces of the extremities.
3. ln older children and adults, the eruption is a chronic dermatitis with lichenification and scaling. The distribution includes the neck, face, upper chest, and characteristically the antecubital and popliteal fossae.
4. Atopics have a characteristic expression.
face---mild to moderate erythema, perioral pallor, and infraorbital fold (Dennie-Morgan lines) associated with dermatitis and hyperpigmentation.
skin---dry and generalized scaling characteristic of ichthyosis vulgaris.
palms---increased linear markings.
D. Special Clinical Features
1. Tendency to develop generalized infections, especially herpes simplex (Kaposi's varicelliform eruptionカポジー水痘様発疹症) and Staphylococcus (Impetigo contagiosa伝染性膿痂疹).
2. White dermographism on stroking involved skin and/or delayed blanch to cholinergic agents
3. Bilateral cataracts occur in up to 10% in the more severe cases; the peak incidence is between 15 and 25 years of age.
4. lchthyosis vulgaris（尋常性魚鱗癬）and keratosis pilaris（毛孔性角化症）in 10% of patients.
5. Nonspecific: Dennie-Morgan lines, loss of lateral portions of eyebrow.
E. Management and Treatment
1. Topical steroids and systemic antihistamines
2. Wet dressings and baths
3. Moisturizers
4. Elimination of diets (in some children, food allergy such as eggs, peanuts, milk, and wheat can cause atopic dermatitis)
5. Education of the patient to avoid rubbing and scratching and also remove emotional stress
6. PUVA
II. Contact Dermatitis（接触性皮膚炎）
・ Contact dermatitis is an inflammatory reaction of the skin precipitated by an exogenous chemical.
・ Irritant contact dermatitis--produced by a substance that has a direct toxic effect on the skin (e.g., acids, alkalis, solvents, detergents).
・ Allergic contact dermatitis---triggers an immunologic reaction that causes tissue inflammation (metals, plants, medicines, rubber chemicals, cosmetic agents).
・ Clinical appearance can range from acute (vesicles) to chronic (Iichenification) eczematous reactions.
A. Incidence1. A frequent problem during our lifetime.
2. Greater than 50% of all occupational illness (excluding injury)
3. ln the industrial setting, 70% is lCD and 30% is ACD.
B. Comparison of lCD and ACD
|
|
ICD |
ACD |
|
Etiology |
primary irritant produces inflammation on first or repeated contact |
delayed type hypersensitivity reaction (type IV) mediated by sensitized T lymphocytes |
|
Latent period |
- |
+ |
|
Langerhans cell |
no relation |
process antigen and present antigenic information to T cells |
|
Dosedependency |
+ |
- |
|
Patch test |
less useful |
useful |
C. Sensitizers
The most common causes of allergic contact dermatitis are:
1. Poison ivy---a frequent cause of ACD in the summer
2. Dyes: hair dyes (paraphenylenediamine), dyes in clothing, shoes and hair nets
3. Metals: nickel (suspenders, jewellery clips, zip fasteners, ear piercing)
4. Rubber compounds---shoes, gloves, suspenders
5. Cosmetics: lipstick, eye-shadow, nail vanish
6. Leather: chemicals present in leather or used in the tanning process
7. Therapeutic preparations:
topical local anesthetics
topical antihistamines
topical antibiotics and antiseptics (neomycin, hydroxyquinolines)
ointment 'bases' and preservatives (ethylenediamine---preservative found in
Mycolog (antifungal drug) cream, dyes, insecticides, rubber accelerators, synthetic waxes, resins. Since ethylenediamine is also the preservative used in aminophylline, it should not be given to an ethylenediamine-sensitive individual.
adhesive plasters
D. Dermatopathology
1. Site: Epidermis and dermis
2. Process:
ACD--- Inflammation with intraepidermal intercellular edema (spongiosis) and monocyte and histiocyte infiltration in the dermis
ICD--- More superficial vesicles containing polymorphonuclear leukocytes Chronic contact dermatitis-"hyperkeratosis, acanthosis, elongation of rete ridges and elongation and broadening of papillae
E. Treatment
1. Identify and remove the etiologic agent.
2. Topical steroids and systemic antihistamines.
III. Seborrheic Dermatitis（脂漏性皮膚炎）
・ A chronic, superficial, inflammatory process characterized by redness and scaling.
・ Affects the hairy regions of the body, especially the scalp, eyebrows, eyelids, nasolabiaI creases, ears, chest, and the intertriginous areas (the axilla, groin, buttocks, and the inframammary folds) where the sebaceous glands are most active.
A. Age Incidence
1. parallels the increased sebaceous gland activity occurring in infancy and after puberty
2. Infancy within the first months
3. Puberty
4. Majority between 20 and 50 years
B. Skin Symptoms
1. Pruritus is variable
2. Worse during winter months
3. lncreased incidence in Parkinson's disease and HIV infected individuals
C. Physical Examination
1. Dandruff (a diffuse scaling) on the scalp
2. Patches and plaques with indistinct margins, mild to moderate erythema, and yellowish, greasy scaling.
3. Sticky crusts and fissures
4. Hair loss is uncommon
D. Distribution and Major Types of Lesions
- based on localization and age -
1. Hairy areas of head scalp, eyebrows, eyelashes (blepharitis), beard (folIicular orifices), cradle cap (in infancy)
2. Face: flush area (butterfly), behind ears, on the forehead (corona seborrhoica)
3. Trunk: yellowish-brown patches over the sternum simulating lesions of pityriasis rosea, tinea versicolor, or tinea corporis
4. Body folds: axillae, groins, ano-genital area, submammary areas, umbilicus diffuse, exudative, sharply marginated, brightly erythematous eruption, fissures are common
5. Genitalia: yellow crusts and psoriasiform lesions
E. Differential Diagnosis
1. Psoriasis
・Involvement of nails, knees, and elbows favors the diagnosis of psoriasis
2. Atopic dermatitis
a. The distinction is often difficult in infancy
b. Exclusive involvement in the diaper area and the axilla favors the diagnosis of seborrheic dermatitis
c. Lesions on the forearms and shins favor atopic dermatitis
3. Dermatophytosis (Tinea capitis, corporis, versicolor) and candidiasis
a. KOH examination and cultures must be done.
4. Histiocytosis X
a. The occurrence of petechiae and purpura should make one suspect this malignant disease.
5. Glucagonoma syndrome (Necrolytic migratory erythema)
a. A rush is found especially on the lower abdomen, groins, buttocks and thighs.
6. Lupus erythematosus
7. Acrodermatitis enteropathica and zinc deficiency
8. Pemphigus foliaceus
9. Rosacea
IV. Lichen Simplex and Chronics ("Neurodermatitis")（ビダール苔癬）
・Pruritus precedes the scratching and is precipitated by frustration, depression, and stress. The scratching then causes the lichenification and further itching, resulting in an "itch-scratch-itch" vicious circle that perpetuates the process.
・A circumscribed area of lichenification resulting from repeated physical trauma (rubbing and scratching).
・in women on the nuchal areas, arms, legs, and ankles
・in both sexes in the ano-genital area
A. History
1. A history of emotional or physical problems, or simply a nervous habit.
2. Preceding the eruption, there is a pruritic area of skin that is scratched, producing a plaque of chronic dermatitis.
B. Skin Lesions
1. Type: A solid plaque of lichenification
2. Color: Brown or black hyperpigmentation
3. Shape: Round, oval, linear (following path of scratching)
4. Distribution: Isolated single lesion or several scattered plaques
5. Characteristic sites: Nuchal area (female), scalp, ankles, tower legs, upper thighs, exterior forearms, vulva, pubis, anal area, scrotum
C. Dermatopathology
1. Nonspecific chronic dermatitis
hyperplasia of all components of epidermis (hyperkeratosis, acanthosis, and elongation and broad rete ridges)
a chronic inflammatory infiltrate in the dermis
D. Treatment
1. Difficult !---the rubbing and scratching must be stopped.
anti-inflammatory agents with occlusive bandages.
intralesional corticosteroids for small localized areas.
tranquilizers and antidepressants have a role in treating underlying emotional difficulties of present.
V. Nummular (Discoid) Eczema（貨幣状湿疹）
・A chronic, pruritic, inflammatory dermatitis occurring in the form of coin-shaped plaques composed of grouped small plaques and vesicles on an erythematous base.
・Mainly on the extensor surfaces of the limbs during winter months.
A. Skin Lesions
1. Type: Closely grouped, small vesicles and papules that coalesce into plaques, often more than 4 to 5 cm in diameter, with an erythematous base with indistinct borders, crusts, and excoriations
Dry scaly plaques with lichenification
2. Color: DulI red
3. Shape: Round or coin-shaped
4. Distribution: Lower legs (older men), trunk, hands and fingers (younger females) occasionally become extensive and generalized, possibly due to autosensitization
B. Differential Diagnosis
1. Dermatophytosis
a. KOH examination of crusts or scales
b. there is no central clearing in nummular eczema
2. Psoriasis
a. biopsy is necessary
3. Mycosis fungoides
a. biopsy is necessary
VI. Dyshidrotic Eczematous Dermatitis (Pompholyx Eczema)（異汗性湿疹）
・A special vesicular type of hand and foot eczema.
・An acute, chronic, or recurrent dermatosis of the fingers, palms, and soles characterized by a sudden onset of deep-seated pruritic, clear "sago-like" vesicles; later scaling, fissures, Iichenification occur.
・Secondary bacterial infection is very often a complication.
・Bullous form is called pompholyx.
A. Skin Lesions
1. Type
a. Early---vesicles, usually small, deep-seated, appearing like "tapioca" in clusters, occasionally bullae, especially on the feet
b. Late---scaling, 1ichenification, painful fissures, and erosions
2. Arrangement: Vesicles grouped in clusters
3. Distribution: hands, palms, sides of fingers, and the dorsal aspects of the fingers and on the feet / bilaterally and symmetrical
4. Nails: Dystrophic changes (transverse ridging, pitting, and thickening)
5. Hyperhidrosis is present in some patients and the lesions are aggravated by excessive sweating of the palms and soles.
B. Treatment
1. Topical corticosteroids
2. Erythromycin or dicloxacillin may be effective (bacterial infection may be present even without obvious signs)
3. PUVA
VII. Stasis Dermatitis (Varicose Eczema)（うっ滞性皮膚炎）
・An eczematous eruption of the lower legs secondary to peripheral venous disease.
・Venous incompetence causes increased hydrostatic pressure and capillary damage with extravasation of red blood cells and serum.
・UIceration occurs frequently.
History
・A chronic, pruritic eruption of the lower legs preceded by edema and swelling.
・Patients with stasis dermatitis have often had thrombophlebitis.
・Aching discomfort in the limb, swelling of the ankle, nocturnal cramps.
A. Skin Lesions
1. Type: Erythematous scaling plaque with exudation, crusts, and superficial ulcers, Brown reticulated hemosiderin hyperpigmentation (on ankles and lower legs), Atrophie blanche
2. Distribution: Localized, predominantly medial aspect of ankle
B. DifferentiaI Diagnosis
1. Cryoglobulinemia
2. Necrobiosis lipoidica（脂肪類壊死症）
3. Pyoderma gangrenosum（壊疽性膿皮症）
4. Contact dermatitis
5. Superficial fungal infection（表在性真菌症）
C. Therapy
1. The cornerstone of managing patients with stasis dermatitis is the prevention of venous stasis and edema---postural drainage (elevation of the feet when sitting, bed rest with elevation of legs) / restriction of standing / elastic stockings / obesity should be controlled by weight reduction program / vein surgery
2. The dermatitis skin is treated with topical steroids and wet compresses of there is oozing or crusting.
3. Allergy to topical preparations occurs in 60% of patients with stasis dermatitis. The compromised epidermal barrier from stasis allows sensitization to occur more easily than with normal skin. Contact dermatitis can easily be misdiagnosed as a flare of the stasis dermatitis. Topical antibiotics are particularly prone to cause allergic contact dermatitis.
VIII. Asteatotic Dermatitis（皮脂欠乏性皮膚炎）
・A relatively common dermatitis that occurs in the winter and in older persons on the legs, arms, and hands and is characterized by dry, "cracked" , fissured skin.
A. Skin Lesions
1. Type: Dry "cracked" skin with red fissures and slight scaling, and sometimes lichenification
2. Arrangement: Diffuse skin involvement, irregular reticulation
3. Distribution: Lower legs, dorsa of hands and forearms. Sometimes generalized.
B. Pathophysiology
1. Asteatosis (loss of lipids) can occur with overbathing, old age, a genetic tendency for dry skin, and high environmental temperature with low relative humidity.
C. Treatment
1. Avoid overbathing with soap.
2. Increase ambient humidity, preferably above 50%; room humidifiers are very helpful.
3. Tepid water baths containing bath oils with immediate liberal application of emollient ointments.
4. Medium-potency corticosteroid ointment.
5. Topical applications of alpha-hydroxy acids, such as glycolic acid and lactic acid, are very helpful.
IX. Psoriasis（乾癬）
・Psoriasis is an inflammatory rash with increased epidermal proliferation resulting in an accumulation of stratum corneum.
・The etiology is unknown, but there are a number of known factors which precipitate or aggravate psoriasis
- Multifactorial inheritance (30% have a family history of the disease)
- Streptococcal infections
- Mental stress
- Trauma: Koebner phenomenon
- Drugs: Chloroquine, lithium, systemic corticosteroids, alcohol
- Obesity
- HIV infection
・The clinical appearance is that of sharply demarcated, erythematous papules and plaques, surmounted by silver scales---representative scaling disorder or papulosquamous disease
A. Skin Lesions
1. Type: Papules and plaques, sharply marginated with marked silvery-white scale. Removal of scale results in the appearance of miniscule blood droplets=Auspitz phenomenon.
2. Color: Salmon pink
3. Shape: Round, oval, polycyclic, annular
4. Arrangement: Zosteriform, arciform, serpiginous, scattered discrete lesions, or erythroderma
5. Distribution: Scalp, elbows, knees, intertriginous areas
BilateraI, rarely symmetrical; most often spares exposed area
Disseminated small lesions without predilection of site (guttate psoriasis)
B. Nails
1. Fingernails and toenails frequently involved, especially with concomitant arthritis.
2. Pitting (icepick-like depressions), subungual hyperkeratosis, onycholysis, and yellowish-brown spots under the nail plate
C. Arthritis
1. Uncommon (5%)
2. Seronegative arthritis distinguished from rheumatoid arthritis by the absence of the "rheumatic factor" in the serum
3. The joints of the hand, the terminal interphalangeal joint (which is usually unaffected in rheumatoid arthritis) and the other joints of the fingers and hand are involved.
4. The knee and ankle joints
5. Psoriatic arthropathy occasionally occurs without the skin lesions of psoriasis.
D. Differential Diagnosis
1. Seborrheic dermatitis: sites and morphology are clues
2. Lichen simplex chronics: may complicate due to pruritus
3. Candidiasis: confused especially with intertriginous psoriasis
4. Psoriasiform drug eruption: beta-blockers, gold, and methyldopa
5. Glucagonoma syndrome (Necrolytic migratory erythema): atypical psoriasiform lesions (annular but with vesicles and erosions), lesions in groin and on face, marked weight loss, unexplained anemia, intermittent diarrhea, stomatitis
E. Dermatopathology
1. Hyperkeratosis, parakeratosis, a decreased granular layer with an acanthotic epidermis
2. An inflammatory infiltrate in the dermis that includes neutrophils
3. Munro's microabscesses formed by polymorphonuclear cells migrated into the stratum corneum
F. Pathophysiology
1. An alteration of the cell kinetics of keratinocytes
shortening of the cell cycle from 2 weeks to 36 h
2. Changes in the level of cyclic nucleotides, arachidonic acid metabolism, the production of cytokines, and expression of adhesion molecules in psoriatic lesions
3. Immunologic alterations
4. Chemotactic factors in the stratum corneum
G. Treatment
1. Factors influencing selection of treatment
a. age
b. type of the lesions
c. site and extent of involvement
d. previous treatment
e. associated medical disorders (e.g., AIDS)
2. Topical: steroids, anthralin, vitamin D3
3. Oral or topical PUVA: oral or topical application of 8-methoxypsoralen (8-MOP) and exposure to UVA
4. UVB therapy
5. Methotrexate (MTX) therapy: folate antagonist, inhibits cellular proliferation
6. Etretinate (Tigason)
7. Cyclosporin
8. Treatment for foci of infection: tonsillectomy for guttate type of psoriasis and pustular psoriasis
X. Other Erythrosquamous Dermatoses
A. Parapsoriasis（類乾癬）
・A group of disorders characterized by a persistent scaling inflammatory eruption.
・Classification of parapsoriasis (Table): Each has distinct skin lesions and several morphologic variants
Classification of Parapsoriasis
a. Large plaque parapsoriasis
b. Small plaque parapsoriasis
c. Pityriasis lichenoides
1) Pityriasis lichenoides et varioliformis acuta
(Mucha-Habermann, PLEVA)
2) Pityriasis lichenoides chronica (PLC)
3) Lymphomatoid papulosis
1. Large plaque Parapsoriasis (parapsoriasis en plaques, large plaque type)
a. A disorder with the potential for progression to malignancy
b. Oval, poorly defined, flat, dermatitic plaques 5〜10 cm in diameter
c. The trunk, especially the buttocks and hips, proximal extremities, the breasts
d. Atrophy, poikiloderma, or the reticulate form of the eruption are signs for the transition to a lymphoma
e. The patient should be carefully examined periodically for evidence of progression
f. Corticosteroid or emollient creams
g. UVB phototherapy or PUVA
2. Small Plaque Parapsoriasis (parapsoriasis en plaque, small plaque type; digitate dematosis)
a. Distinguished from large plaque parapsoriasis on the following grounds the morphology of the lesions benign course
b. Small to moderate-sized plaques, less than 5 cm in diameter
c. Primarily on the trunk and proximal extremities
d. Red-blue to yellow, with distinct borders and thin, adherent scales
e. Corticosteroid or emollient creams
f. A chronic course lasting from months to years
g. No progression to malignancy is to be expected
3. Pityriasis lichenoides et varioliformis acuta（急性痘瘡状苔癬状粃糖疹）
a. An acute or subacute and at times relapsing papulovesicular disorder
b. lnfectious origin, possibly viral may be responsible (EB virus?)
c. An eruption characterized by multiple disseminated, variceIIiform cutaneous lesions
d. Accompanied by mild fever, malaise, headaches, arthralgia
e. Papules present a purpuric character and the centers are vesiculopustular, then necrotic and are covered by a dark adherent crust
f. Lymphocytic vasculitis or perivasculitis---deposits of lgM, C3 and fibrin are present
g. Extravasation
h. The disease fades within weeks or months
i. PUVA, UVA, UVB
4. Pityriasis lichenoides chronica（慢性苔癬状粃糖疹）
a. An symptomatic chronic eruption of multiple lesions, evenly distributed on the trunk and limbs
b. Small lichenoid papules, oval or round, 3 to 10 mm in diameter
c. After the regression, a pigmented macule, or a transient or persistent leukoderma remains
d. PLEVA changes to PLC
e. Phototherapy is the best choice.
5. Lymphomatoid papulosis（リンパ腫様丘疹症）
a. First described as a recurrent, self-healing, papulovesicular eruption
b. Clinically similar to PLEVA, but the presence of atypical lymphocyte differentiates this from it histopathologically
c. Several patients with lymphomatoid papulosis have developed systemic lymphoma
d. Regarded as a low-grade lymphoma
e. All patients require long-term follow-up to make sure that lymphoma does not develop
B. Palmoplantar Pustulosis (Pustular Palmoplantar Psoriasis)（掌蹠膿疱症）
・A chronic, relapsing eruption limited to the palms and soles and characterized by numerous sterile, yellow, deep-seated, small pustules that evolve into dusky-red macules. Subtype of psoriasis
1. Epidemiology and Etiology
a. Age: 50 to 60 years
b. Sex: More common in females (3.4:1)
2. Skin Lesions
a. Type: Vesicles and pustules / erythema and scaling
b. Distribution: Localized to palms and soles
3. Pathophysiology
a. Alteration of chemotactic factors
b. Allergic reaction to metals (especially dental materials)
c. Focus of infection: tonsillitis, teeth, gingiva or gum diseases
d. Metabolic disorder
e. Smoking
4. Treatment
a. Topical steroids
b. PUVA
c. Treatment for foci of infection: tonsillectomy
d. Removal or change of dental materials
e. Etretinate
f. Colchicine---potent inhibitor of leukocyte motility
C. Pityriasis Rosea Gibert（ジベルバラ色粃糠疹）
・Exanthematous, maculopapular, red, scaling eruptions occur on the trunk
・Probably caused by an infections agent
1. Age: 10 to 35 years
2. Skin Lesions
a. Type
1) Herald plaque--80% of patients, 2 to 5 cm, bright red, fine scale
2) Exanthem---Fine scaling macules and papules with typical marginal collarette
b. Shape: Oval
c. Distribution: The long axes of the lesions follow the lines of cleavage in a "Christmas tree" distribution. Trunk/proximal aspects of the arms and legs
3. Differential Diagnosis
a. Drug eruptions: captopril
b. Secondary syphilis: serologic test
c. Guttate psoriasis: no marginal collarette
d. Parapsoriasis
e. Seborrheic dermatitis
f. Tinea versicolor: KOH examination
g. Erythema migrance
4. Course
a. Spontaneous remission in 6 to 12 weeks or less.
D. Pityriasis Rubra Pilaris (RPR) (Devergie's disease)（毛孔性紅色粃糖疹）
・A chronic disorder characterized by reddish-orange, scaling plaques and keratotic follicular papules
・Familiar or acquired form
1. Skin Lesions
a. Type
1) Early lesions---FoIIicular papules
2) Later Lesions---Diffuse scaly erythematous lesions
3) Salmon color of the scaly plaques and the presence of small islands of normal skin within large coalescent area of the eruption
b. Distribution: scalp, face, ears, palms and soles, trunk, neck, extremities
2. Dermatopathology
a. Focal hyperkeratosis, parakeratosis
b. Perifollicular inflammatory infiltrate
c. Liquefaction
3. Treatment
a. Etretinate
E. Lichen Planus（扁平苔癬）
- Classically a papulosquamous disorder
- May also present as vesicular or bullous, hypertrophic, atrophic, annular, follicular, erosive, actinic, or erythematous variants
- lnvolved sites are flexor surfaces, mucous membranes, and genitalia
- AIteration of the nails, reflecting mild or marked focal or diffuse inflammation of the nail matrix to the edge of the nail
- Drug-induced: heavy metals, photographic chemicals
Variations of Pattern in Lichen Planus
a. Difference in configuration
1) Annular
2) Linear
b. Difference in site
1) Mucous membrane
2) Genitalia
3) Nails
4) Scalp
c. Difference in morphology
1) Hypertrophic
2) Follicular
3) Vesicular and Bullous
4) Erosive and ulcerative
5) Atrophic
6) Malignant degeneration
7) Actinic
8) Erythematous
9) Exfoliative
1. Dermatopathology
a. Hyperkeratosis, irregular acanthosis, focal thickening of the granular layer
b. Liquefaction degeneration of the basement membrane and basal cells (degenerate keratinocytes: colloid bodies, eosinophilic, or Civatte bodies)
c. Bandlike lymphocytic and histiocytic infiltrate in the upper dermis
2. Treatment
a. Topical steroids
b. PUVA
c. Etretinate
d. Cyclosporin
F. Lichen Nitidus（光沢苔癬）
・A chronic, generally asymptomatic micropapular dermatosis.
・Affects the penis, forearms, breasts, and other portions of the trunk
・The concurrence of lichen nitidus and lichen planus is common
1. Skin Lesions
a. Type: discrete, smooth, flat minipapules that are roughly circular in outline uniformly pinpoint to pinhead in size
b. Color: pink or flesh-colored and present a glistening appearance
c. Distribution: the shaft and glans of the penis, flexural aspects of the forearms and wrists, the breasts, the abdomen, and the buttocks
2. Treatment
a. Spontaneously resolve after many years.
b. PUVA, etretinate
G. Lichen Striatus（線状苔癬）
・A clinically distinctive, self-limiting linear eruption (usually within 12 weeks) of unknown etiology
・Children between the ages of 5 and l2 years represent the usual group affected, although the disease has been seen in infancy and old age.
・Girls:boys=2:1
1. Skin Lesions
a. Type
1) discrete, pink papules, 2 to 4 mm in width, which soon coalesce, some to form small plaques
2) papular or lichenoid, with an inconspicuous scale
3) rarely verruciform and vesiculobullous lesions
b. Distribution: extend linearly over the affected part, reaching a length of several centimeters or running the entire length of an extremity one arm or leg is usually affected, although the buttocks, neck, and trunk may be involved
2. Treatment
a. As the disorder disappears spontaneously, usually 12 weeks, topical corticosteroids or an emollient cream to minimize dryness can be used.