Dermatology Flashcards
top 4 categories of skin problems
- inflammatory disease
# 2. infection - tumors
- other
7 broad categories of skin disease
- dermatitis
- papulosquamous
- urticaria/erythema
- infection
- follicular
- tumors
- other
Wheels
(indicative of urticaria, NOT the same as urticarial vasculitis)
= pruritic dermal swellings sharply defined w/o surrounding erythema.
*EACH individual lesion lasts less than 24 hrs
Abscess
a furuncle or carbuncle (round, red, tender, may rupture) found on the back or thighs, that is a localized infection caused by Staph. aureus.
Tx: antibiotics, mupirocin, wash hands well w/ soap.
Scalded Skin Syndrome
Diffuse erythema w/ fever, followed by desquamation that travels from the head and shoulders to the trunk; usually in infants.
Caused by Staphylococcal toxins.
Tx: Nafcillin IV (emergency)
Bullous Impetigo
Clusters of vesicles on face, trunk, extremities and perineum that turn to bullae then crust over; in children ages 2-5.
Cause: Group II streptococci
Tx: Mupirocin, Dicloxacillin, or cephalexin
Non-bullous Impetigo
Clusters of vesicles which fill with pus then dry into “honey colored” crusts, mostly on the face.
Cause: streptococci, but may be contaminated w/ staph.
Tx: Mupirocin, Dicloxacillin or cephalexin
Erysipelas
Sharply demarcated erythema and swelling in adults, on the face, ears, or lower legs; acute onset often w/ initiating skin lesion.
* 4 telltale signs: Rubor (red), Calor (hot), Dolor (painful), tumor (swelling); hard to distinguish from cellulitis.
Cause: Group A strep or staph.
Tx: penicillin, cephalosporin or erythromycin
Scarlet Fever (rash)
** 1st 48 hrs: white coated “strawberry tongue,” turns red after 5 days; accompanying small papules on neck that spread. Followed by brawny desquamation.
Cause: group A strep
Tx: penicillin, erythromycin, dicloxacillin
Ecthyma
Deep infection in butt, thighs, or legs usually in tropics; = vesicle or pustule that becomes ulcer, scars.
Cause: Staph or strep pyogenes
Tx: penicillin, erythromycin, cephalosporin.
Ecthyma gangrenosum
red macule –> papule –> hemorrhagic bulla –> necrosis & gangrenous ulcer (w/ greenish tint & pink halo/edge)
* occurs in immunocompromised only*
Cause: pseudomonas
Tx: 3rd generation cephalosporins
haemophilus cellulitis
purple/red swelling of face, in children 6 mo - 3 years old; occurs w/ URI & otitis media usually.
=> “preseptal cellulitis” if affects eyelid (dangerous complication)
Cause: Haemophilus infection
Tx: IV cephalosporins
Rocky Mountain Spotted Fever
pale or red macules appearing 1st on wrists and ankles, then spreading to palms and soles of feet, = vasculitis.
Other Sx: fever, malaise, vomitting; Risk hepatomegaly.
Cause: rickettsia infection from tick bite (esp. in North/South Carolina)
Tx: doxycycline
cutaneous signs of gonococcemia
a few medium-small crusty pustules over red base on extremities, usually last ~4 days.
Other Sx: fever, myalgia, tenosynovitis; acute abdomen
Cause: gonorrhea infection spread to blood
Cutaneous signs of meningococcemia
diffuse petechia or hemorrhagic purpura on face and extremities; usually in children under 2.
Other Sx: sudden onset of fever and severe headache, stiff neck
Cause: Neisseiria meningitidis
Complication: “Waterhouse Fridericksen Syndrome” = massive bleeding into skin and adrenal glands from septicemia.
Onychomycosis
fungal infection of finger or toenails.
a) Distal = yellowish hyperkeratosis, most common (in anyone)
b) Proximal = white discoloration under proximal nail fold, in immunosuppressed (esp. AIDS)
Dx w/ KOH
Athlete’s Foot (tinea pedis)
a) interdigital - damp, flaky & itchy btwn toes
b) vesiculobullous - blisters on heel, insole or ball of foot
c) moccasin - diffuse scaliness across whole sole of foot
Dx w/ KOH, Tx = topical
tinea cruris (jock itch)
= contamination from tinea pedis, ringed expanding erythematous plaque on inner thighs & butt.
spares penis & scrotum
Dx w/ KOH, Tx = topical + treat tinea pedis.
tinea corporis vs. versicolor
Corporis: expanding erythematous & scaly circular plaque; on face, trunk or extremities
Versicolor: brown, pink or hypopigmented scaly patches on trunk;
* “spaghetti & meatballs” appearance under microscope
Candidiasis
a) Intertriginous/Diaper: broad erythematous plaque in moist areas (axilla, submammary, inguinal)
b) Perinychia: thickened, red nailfolds
c) Thrush: in mouth (mucosal surfaces) –> Chronic Mucocutaneous if child w/ T cell deficiency.
Cause: yeast (candida), = opportunistic, esp. immunocompromised but not excusively!
Sebhorreic keratosis
common benign epidermal growth, esp. on face/trunk & age 30+;
= well-marginated pigmented papule or plaque.
Tx: liquid N, curettage or shave excision
actinic keratosis
pre-cancerous epidermal growth,
= rough, scaly, red plaque/papule, esp. on sun-exposed areas.
** 10% convert to squamous cell carcinoma!**
Tx: cryoTx, acid peel, curettage. best = prevention!
warts (verruca vulgaris)
benign epidermal hyperplasia due to HPV infection,
- common, plantar, periungual, mosaic (if transplant/immunosupr.)…
*esp. in school children or ppl w/ risks (athletes, animal exposure)
**spread w/ contact!
Tx: salicylic acid, 3M duct tape, cryotherapy, candida Ag, laser…
molluscum contagiosum
Soft, domed papules from poxvirus infection of epidermal cells;
- esp. in kids (face, trunk, extremities) or genitals in adults
Tx: spontaneously remit, or cryoTx. *hard to Tx in AIDS (persistant)
Condyloma acuminatum
= genital warts (epidermal hyperplasia from HPV infection),
** oncogenic –> cervical carcinoma, squamous cell carcinoma!
Spread: sexually OR non-sexually (skin/mucosal surf. contact)
Tx: salicylic acid, cryotherapy, excision, laser, etc.
Corns (clavus)
localized epidermal thickening secondary to chronic friction/P;
= tender, mostly on toes/feet, translucent w/ intact skin lines.
Complications: ulcers, infection, osteomyelitis… (esp. if diabetic)
Tx: paring, change footwear
Freckle vs. Lentigo
Both: hyperpigmented macules
Freckles (ephelis) = increased melanin (normal # melanocytes)
Lentigo = increased # melanocytes (Tx w/ laser, cryoTx)
Nevi
= moles (junctional: dark, dermal: pale, complex),
*increased risk melanoma w/…
#1: giant congenital nevus (w/ CNS involvement!)
2. large congenital nevus (>20 cm)
3. atypical (small, appear over time): MAY precede melanoma
melasma
patchy macular hyperpigmentation, esp. on face;
from hormones (ie: pregnancy, contraceptive) & UV exposure.
* harder to treat if dark skin tones.
Epidermal cyst
inflammation of epithelial lining of hair follicle infundibulum (@ top),
–> tender & inflamed, w/ central punctum +/- foul odor.
Tx: excise remove lining or will recur
Pilar cyst
tender, inflamed outer sheath of hair follicle root;
* no central punctum, mostly on scalp.
Tx: excise
Hemangioma
benign proliferation of blood vessels in dermis.
- cherry: acquired/senile, will not go away
- of infancy: present @ birth. a) rapidly enlarge (1/3), or b) self-resolve –>1/3 go away completely.
Tx: evaluate early, excise if enlarging! (may ulcerate or fibrose)
dermatofibroma
focal dermal fibrosis, w/ thickening & hyperpigmentation;
from minor trauma (ie: shaving), w/ “dimple sign.”
Tx: excise/laser
Keloid
excessive collagen proliferation after initial (minor) trauma,
Tx: intralesional kenalog/steroid, pulse dye laser…
do NOT excise bc will grow back!
Lipoma
benign accumulation of subcutaneous fat,
* usually asymptomatic.
Tx: excision (if needed)
Basal cell carcinoma (“BCC”)
malignant neoplasm from basal cells of follicular epidermis,
*most common skin cancer, from UV exposure.
* Metastasis = rare; many types, morpheaform = most aggressive.
Tx: Mohs surgery (#1), or excision & radiation
Squamous cell carcinoma (“SCC”)
keratinocyte malignancy in epidermis (thick, extends into dermis);
Risks: solid organ transplant pts, UV or radiation exposure, actinic keratosis (= precursor)
* Locally invasive, + metastasizes. *p53 mut/Ras activation
Tx: Mohs surgery (#1)
melanoma
malignant melanocyte neoplasm; No Sxs, *most deadly skin cancer.
Precursors: congenital or atypical nevi, may be de novo
- superficial spreading = most common
- Nodular (vertical growth) = deadliest
Also: Lentigo malignans (elderly), ocular, or apigmented (skin color!)
Tx: Surgery (prevention is better)
check sentinel lymph nodes for metastasis!
Dermatitis (types, general characteristics)
Histo: superficial perivascular inflammation, with dermal edema, hyperplasia, & hyperkeratosis.
Types (7): atopic, contact, dyshydrotic, nummular, neurodermatitis, sebhorreic, stasis.
“Atopic triad”
the 3 main problems that typically coexisit with ATOPIC dermatitis:
- atopic dermatitis
- asthma
- allergic rhinitis
atopic dermatitis
series of remissions & exacerbations, w/ skin hyperirritability;
Onset: infancy, presentation changes over time (NOT an allergic rxn)
- infancy: on face, elbows & knees (extensor surfaces)
- adulthood: on neck, inner elbow/knee, & ankles (flexor surfaces)
–> w/ lichenification in adulthood, decrease severity as age.
associated w/ fillagrin mutation!
Tx: moisturize, topical steroids, antihistamines/antibiotics, UV Tx…
Hannifin-Rajka dermatitis
chronic, recurrent atopic dermatitis w/ pruritis; + family Hx.
(same pattern as standard atopic dermatitis)
* MUST also have 3 minor features (facial/ocular involvement, hyerreactivity, etc.)
pathogenesis of atopic dermatitis
Atopic Langerhan’s cells hyperstimulate T cells,
–> excessive T cell reaction to antigen (penetrates skin barrier)
==> cytokine activation & immune/inflammatory response.
(cytokines = in chronic phase)
Common atopic dermatitis complications
secondary infections (bc of irritated, compromised skin),
- eczema herpeticum: HSV on face, w/ pustular papules & fever.
- molluscum contagiosum: widespread papules w/ central plug
- impetigo: staph aureus –> honey colored crusts
Contact dermatitis
= allergic rxn to skin exposure.
- type I: IgE rxn (esp. to Latex)
- type IV (DTH): T cell mediated, severe (poison ivy, metals, fragrances, etc.)
*need >1 exposure to react (>1 wk btwn, 2nd rxn appears 8-24 hrs after actual exposure)
Dx: T.R.U.E. test (controlled patch exposure to allergens)
Tx: avoid the causative allergen/material
pathogenesis of DTH contact dermatitis
(5 steps)
- Sensitization (7-21 days): Ag into epidermis, binds to dermal dendritic cell, APC to lymph nodes, presents Ag to naive T cells.
- Memory: Ag-specific T cell expansion (w/ CCL27 expression)
- “Challenge” (2nd exposure): 8 hrs - 5 days to recognize the Ag
- Inflammatory Rxn: vasodilate, activate endothelium –> release mediators & recruit leukocytes (inflammation phase)
- Resolution: macrophages remove allergen.
Pompholyx (dyshydrotic dermatitis)
=> large, blistering bullae/vesicles on palms & soles.
itchy & painful, but NOT inflammatory!
* may dry into crusty plaques on fingers or feet.
Dx: scrape to rule out tinea.
Sebhorreic dermatitis
greasy yellow scale on face/ears, scalp, axilla, or groin.
* not usually itchy.
Causes: hormones (& pregnancy), immune abnormalities/Malassezia furfur, neuro diseases (esp. Parkinson’s!)
stasis dermatitis
= dermatitis on legs (common in adults!), chronic inflammation.
Cause: chronic venous insufficiency bc valve incompetency
*may ulcerate!
Tx: compression, topical corticosteroids
Nummular dermatitis
circular red, itchy spots of inflammation on legs.
= combo of stasis & atopic dermatitis,
Tx: emollients, topical corticosteroids
Neurodermatitis
- lichen simplex chronicus: itchy, leathery, hyperpigmented plaque;
- cause: habitual scratching (psych.)
- prurigo nodularis: hard keratotic nodules on extensor surfaces;
- cause: obsessive picking of skin (psych.)
Tx: anxiolytics (manage OCD), topical/intralesional steroids
- cause: obsessive picking of skin (psych.)
