skin

 

Layers of epidermis

Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale

 Wood’s lamp examination

disease	appearance
T. vesicolor	Golden yellow
P. aeruginosa	Aqua green
Porphyria cutanea tarda	Pink-orange
Leprosy	Blue-white
Hypopigmentation	Pale white
Hyperpigmentation	Purple brown
Vitiligo	Bright-white/ blue-white
Albinism	Bright-white/ blue-white
Erythrasma	Coral red, pink
T. schonlenii	Pale green
Microsporum	Yellow green
Tuberous sclerosis	Blue white
Pseudomonas infection	Greenish white or pale blue
Porphyria cutanea tarda	Pinkish red –urine
Pityriasis versicolor	Golden yellow fluorescence
Tinea capitis	Green fluorescence

Special types of Acne

Acne conglobata	Severe cystic acne with comedones, abscesses, sinuses and nodules.
Acne fulminans	Inflammatory nodules, cysts plaques, fever, constitutional symptoms, treated with steroids.
Acne venerata	Caused by contact with comedogenic chemicals
Acne cosmetica	Caused by contact with comedogenic cosmetics
Tropical acne	Acne on back, buttocks, thigh because of high humidity of tropical climate.
Acne excoriae Picker’s acne	Seen in females caused by compulsive picking of  the lesions

Occlusion tetrad

Nodulocystic acne Dissecting cellulites of scalp Hydradenitis suppurativa Pilonidal sinus

Phases of growth of hair

Anagen	growing phase
Telogen	resting phase
Catagen	transitional phase

TYPES OF ALOPECIA

Alopecia areata	Patches of smooth area with loss of hair. At the periphery of patches are exclamation hair ( attenuated bulb with splayed pigmented distal end)
Alopecia totalis	Total loss of scalp hair
Alopecia universalis	When hair has been lost over the entire body

Graypatch	Characterized by scaly gray patches with stubs of broken hair and easy pluckability of hair. Caused by ectothrix   fungi. Shows greenish yellow fluorescence under woods lamp.
Black dot	Areas of alopecia studded with black dots representing hair broken off at surface of the scalp, caused by endothrix fungi.
Kerion celsii	Is a boggy indurated area exuding pus. May be followed by scarring and permanent alopecia
Favus/ Witkop	Affects scalp, glabrous skin, nails. Concave Sulphur yellow crusts / scutulae form around loose wiry hair, atrophy leads to smooth glossy thin paper/ scars.

*Atopic dermatitis, infantile eczema/ neurodermatitis Also called Besnier’s prurigo

Signs of atopy

Dennie Morgan folds (Extra fold beneath the eyelid is called the Denny Morgan fold) Extra crease line just below the lower eyelid, exceeding midline(pupil) Keratosis pilaris Follicular papules on the extremities Hertoghe’s sign- Thinning of lateral eyebrows White dermographism- Tripler response o is replaced by blanching of skin

pemphigus	pemphigoid
Nikolsky sign present	Absent
Bullae are intraepidermal and flaccid	Bullae are subepidermal and tense
Mucosa involved	Mucosae are not involved
Acantholysis present	Absent
Involves upper part of body	Lower part of body
Age-40-60	Age 60-80
Prognosis poor	Prognosis good

Nikolsky sign

Sliding of superficial layers of skin on the deeper layers when a tangential force is applied with the pulp of thumb, especially over bony prominences

Positive in

Staphylococcal scalded skin syndrome- Toxic epidermal necrolysis Pemphigus Epidermolysis bullosa congenital Pemphigus

 

*Butcher’s wart / Anatomists wart- Cutaneous tuberculosis / verrucosa cutis

Slowly progressive asymptomatic lesion that follows penetrating trauma

Treated with akt.

*Pseudofolliculitis barbae-

Seen in blacks. Caused due to close shaving of curved hair, which pierce the skin.

Treatment is to stop shaving.

 

*Pityriasis versicolor

Hypopigmented or hyperpigmented perifollicular finely scaly macules coalescing to form patches seen on upper arm, neck, trunk, underarms.

Caused by Malassezia furfur.

*Ping pong scabies- mite is transmitted from one house member to another.

*Inguinal bubo appears 2- 4 weeks after genital ulceration.

*Bull’s eye lesion or iris lesion or target lesion

Seen in erythema mutiforme

*Miyagawa’s granulocorpuscles are found in lymphogranuloma venereum, when smears are stained with Giemsa

*Commonest cause of photoallergic dermatitis in India is Parthenium

*Impetigo of Bockhart

Acute superficial folliculitis

Pustules heal without scarring.

*Lyell’s disease-Toxic epidermal necrolysis.

*Pastia’s line-

Linear petechial lesions found in scarlet fever in antecubital and Axillary folds.

*Desert sore / Veldt sore is a superficial ulcer caused by corynebacterium diphtheriae.

*Meleney’s gangrene-

Caused by peptostreptococcus and staphylococcus aureus or enterobacteriaceae.

*Hot tub folliculitis

Caused by pseudomonas  aeruginosa. Occurring 1-4 days after bathing in hot tubs, swimming pool or whirlpool.

*Rose spots of salmonellosis occur between umbilicus and nipples.

*Chicken pox

Rash is described as dew drops on rose petals

Centripetal distribution.