Dermatology Flashcards
Cells in epidermis
a) Keratinocytes
b) Melanocytes
c) Langerhans cells = antigen- presenting cells. Pale dendritic cells which contain
Birbeck granules on electron microscopy
d) Merkel cells- epidermal nerve cells.
epidermal appendages
Pilosebaceous follicles: hair plus sebaceous glands (which open into hair canal); occur everywhere except on palms and soles.
Apocrine sweat glands: modified sebaceous glands; open into hair follicle or directly
onto skin; localized to axillae, nipples, perineum, genitalia
Eccrine sweat glands: on whole skin surface; secrete clear fluid containing electrolytes; sympathetic innervation.
functions of skin
sensation physical protection temp regulation chemical protection and lubrication immunological hormonal- Sex hormone metabolism, Production of vitamin D display- cosmetic toxic substance excretion
pathological terms
Hyperkeratosis -thickening of stratum corneum (SC)
Acanthosis -thickening of stratum spinosum
Parakeratosis -nuclei retained in cell of thickened SC
Acantholysis -loss of adhesion between epidermal cells
what can be used in topical treatments
Wet dressing- physiological saline can be made at home (2 teaspoons salt/litre water);
potassium permanganate (crystals in water to make pale pink solution) - useful if infection is present
Active ingredients such as sulphur, coal tar or corticosteroids can be incorporated into some
of the above vehicles
unguentum) emulsificans (= UE, contains liquid paraffin, white vaseline and emulsifying waxes) and Ung. Emulsificans aquosum (UEA = UE + 20% water
Useful antiseptic preparations include
povidone-iodine (Betadine) cream or ointment, Furacin ointment (nitrofurazone- causes allergic contact dermatitis) Hibitane cream (chlorhexidene- causes irritant dermatitis, avoid in eczema) cream
Antibiotic ointments
Terramycin (oxytetracycline plus polymyxin B), Polysporin (polymyxin + bacitracin),
Bactroban (mupirocin) skin and nasal ointment
corticosteroids indications
include acute eczema, pemphigus vulgaris, systemic lupus erythematosus and leprosy reactions
what antibiotics for widespread, deep or severe skin infections. Most skin infections are mixed Staph and Strep.
Penicillin VK is usually note effective for both and is
poorly absorbed in adults and older children
erythromycin,
cloxacillin
anti fungals used in dermatology
Griseofulvin - effective only for dermatophytes
Nystatin - effective only for Candida
Amphotericin B – very useful for oral candidiasis.
Imidazoles: broad spectrum anti-fungal agents active against both yeasts and dermatophytes
Triazoles: Itraconazole (Sporonox) – used orally for candidiasis, deep fungi
Fluconazole - Mainly used for candidiasis
and cryptococcal meningitis.
Terbinafine – mainly for dermatophyte infections, including Amorolfine (Loceryl) - nail laquer used 1-2 times per week
other drugs used in dermatology
Retinoids- Inhibit keratinization, sebum secretion and
inflammation, teratogenic
Dapsone - very useful in
dermatology especially for dermatitis herpetiformis, pemphigoid, various pustular dermatoses and Vasculitis
5-Fluorouracil (Efudix): 5% cream used for removal of solar keratosis
which dz is vitiligo occasionally associated with
Hashimoto’s pernicious anaemia diabetes mellitus Addison’s hypoadrenalism alopecia areata
vitiligo Rx
Potent topical corticosteroid creams- try for 3 months only
PUVA (psoralen) (oral or topical) + UVA) or narrow band UVB
Sunscreens and cosmetic covers
cosmetic onchronosis facts
Due to the use of bleaching creams containing
hydroquinone
Worst on sun-exposed parts of face and neck; maximal on malar region andaround the eyes
impetigo
Lesions start as superficial, subcorneal, thin walled vesicles which soon rupture to exude serum (streptococci) or purulent (staphs) which dries to form crusts
Rx- Antiseptic or anti biotic ointments (e.g. Furacin, Terramycin, Polysporin,
Bactroban)
ecthyma
Same as impetigo but infection extends into dermis and lesions heal with scarring.
Most common on lower legs following insect bites or trauma.
Treatment: Always give systemic antibiotic such as erythromycin, cloxacillin or sulphonamide
(not tetracycline in children)
folliculitis
most common in the beard area (sycosis barbae) but may occur on any hairy part of the body.
Treatment: antiseptic lotions; antibiotics, topical and / or systemic
furuncles
Deep staphylococcal infection in and around hair follicle
Recurrent boils (furunculosis) underlying precipitating
factors- diabetes, other causes of immunosuppression and poor hygiene.
Treatment: Topical antiseptics, according to culture results, and treat carrier state in patient
and contacts
strep skin infx
cellulitis- deep diffuse dermal infection, ill circumscribed, usually warm and tender
with lymphadenitis
erysipelas -supf well circumscribed rash extending to the subcutaneous lymphatic vessels, common
sites face and legs
Treatment: I.V. penicillin
Eliminate source of infection
Common wart
raised nodular type common in children in whom they undergo spontaneous regression sooner or later.
Treatment- Topical irritants: e.g. lactic acid and salicyclic acid paints , silver nitrate sticks. If necessary freezing with liquid nitrogen or curettage with or without light
electrodessication
Home remedy: Cut lemon peel to size of warts
can apply 25% salicylic acid ointment under plaster
or paint with 20% formalin or monochloracetic acid in plantar wart
Plane warts
multiple flat warts on face or limbs usually in children and young adults.
Treatment- topical irritants: benzyl benzoate, retinoic acid. 5- fluorouracil cream, Lemon peel home remedy
Venereal warts
there may be warts in urethra, vagina or anus as well.
Treatment- Topical imiquimod
electrocauterization, freezing, CO2 laser
20% podophyllin- Do not use podophyllin on mucosal
surfaces or in pregnancy (absorption and toxicity).
molluscum contagiosum
Dome shaped papules with a central
umbilication through which a white cheesy material can be expressed.
Treatment: Topical imiquimod
produce local inflammation (after which they regress) by either inserting sharpened match stick dipped in phenol into central umbilication, or freezing with liquid N₂, or light curettage
rubbing on retinoic acid or benzyl benzoate 2-3 times daily
express contents with comedo expressor
herpes simplex
Primary infection: usually gingiva-stomatitis in infants Secondary infection: “fever blisters” (herpes febrilis, “cold sores”): mostly on face,
especially lips but may occur anywhere.
Recurrent herpes simplex: in some individuals; precipitated by fever, sun exposure,
menstruation etc. Mostly on
face, then genitalia, but may occur anywhere.
Generalized herpes simplex – mainly in immunosuppressed patients; vesicles are diffuse,
not grouped
Rx- valacyclovir/ famciclovir
herpes zoster
Zoster results from reactivation of latent virus in dorsal root ganglia of peripheral and cranial nerves
Mostly in adults and geriatrics
Highly suggestive of HIV infection in young persons
Rx- oral acyclovir /famciclovir/valaciclovir which should
be started in the first 72 hours
IV acyclovir for severe disseminated zoster
Antibiotics if secondarily infected
Eye consult for ophthalmic zoster
HIV drug sensitivity
Especially co-trimoxazole and anti-TB drugs (widespread erythematous maculo-papular and lichenoid drug rashes)
SJS and TEN due to drugs such as sulphonamides and HAART (especially efavirenz and nevirapine)
leprosy Rx
rifampicin, dapsone and clofazimin
Treatment must be continued during reactions
reactions in leprosy Rx
cell mediated- Corticosteroids started in high doses) and tapered slowly. For reversal reactions at least 6 months of corticosteroids required as
treatment perpetuates the reaction. Shorter corticosteroid treatment needed for downgrading
reactions
humoral- Mild cases- no treatment or anti-inflammatory drugs. Severe cases- systemic
corticosteroids, increased dose of clofazimine and thalidomide if available
what develops in humoral leprosy reaction
Erythema nodusum leprosum: painful skin nodules, neuritis, arthritis, uveitis, glomerulonephritis
true TB infx
Tuberculous chancre- Nodule or ulcer with enlarged regional nodes
Lupus vulgaris- mostly head and neck, often starts in nos
Warty tuberculosis- (tuberculosis verrucosa cutis) mainly on extremities; hyperkeratotic warty surface
Scrofuloderma- sinuses and fistulae on skin resulting from tuberculous abcess formation
in underlying organ- usually lymph node but may be bone or joint, most common in neck and axillae.
Tuberculous gummas- Multiple lesions resembling scrofuloderma, resulting from haematogenous spread.
Miliary TB- with HIV infection
immunolgoical reactions of TB
- Papulonecrotic tuberculides (PNT): Widespread, symmetrical, mostly over elbows, knees
and buttocks but anywhere. Papules, pustules, ulcers and round to oval atrophic scars
(so-called varioliform scars). - Nodular tuberculides- mainly on lower legs
Erythema nodosum and nodular Vasculitis
Erythema induratum- nodules with ulceration- mainly on calves. - Lichen scrofulosorum- small, firm papules, grouped or diffuse on trunk or limbs
cutaneous sarcoidosis
A. SUBACUTE, TRANSIENT- erythema nodosum on lower legs plus hilar
lymphadenopathy.
B. CHRONIC, PERSISTENT- skin lesions either localized or widespread sometimes associated with bone and/or lung involvement
Lupus pernio: name given to type of sarcoidosis presenting
with purplish plaques on nose, cheeks and ears.
eczema
An immunologically mediated inflammatory skin disorder characterized in its acute stage by vesicle formation in the epidermis
acute, subacute, chronic, exfoliative
atopic eczema
association with asthma, hayfever
raised serum IgE in some patients, Association
with dryness of skin and ichthyosis.
A relatively common type of eczema in infants and children.
seborrhoeic dermatitis
Sometimes elicited or aggravated by infection (Staph, Strep, Pityrosporum yeasts)
Mostly subacute or chronic with erythema and scaling but may become acute and weeping.
Scalp, face, presternal and moist and hairy flexures (axillae, groins) commonly affected
eczema elicited by various factors
local- Dryness, Infection, Contact dermatitis- Primary irritant or Allergic- e.g. nickel , Venous hypertension, Trauma, UVL, Sweating
systemic- Infections e.g. tonsillitis
Drugs e.g. penicillin
eczema Rx
AB- flucloxacillin jor clartithromtcin Corticosteroids- topical mostly; systemic only if severe and for shortest possible time. Ultraviolet light (UVB or PUVA), cyclosporine and azathioprine pimecrolimus (Elidel), tacrolimus
ptyriasis rosea
relatively common disease in young adults
tends to occur in minor epidemics, mostly in spring and
autumn
Rash characteristically involves trunk and proximal parts of extremities
Self- limiting within about 8 weeks
Treatment: Diluted corticosteroids creams and sun exposure may shorten attacks
lichen planus
Aetiology -unknown (but increasing association with certain drugs, e.g. thiazide diuretics, oral hypoglycea emic agents, methyldopa and anti-TB drugs reported).
Course- sudden onset; most cases subside within 3 months to 2 years, but many relapse
Clinical: Anywhere, but commonly on anterior aspects of wrists and ankles, wickams striae, koebner phenomenom
characteristic severe itch and violaceous colour
Treatment: topical corticosteroids, under occlusion where practical. If severe enough, oral
steroids.
Lichenoid Drug Eruptions
Rash resembles lichen planus but may be more severe and extensive; slow resolution after drug withdrawal.
Commonest drugs implicated are gold, antimalarials (chloroquine,
mepacrine), thiazide diuretics, antituberculotics (PAS, streptomycin, INH).
Also from external contact with photographic colour developers
