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Flashcards in Skin Deck (69):

Molluscum contagiosum


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• Poxvirus (DNA virus) in children

• Bowl-shaped lesion filled with keratin, molluscum bodies (viral particles)

• Disseminates with HIV


Rubeola (measles)

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• Paramyxovirus (RNA)

• Cold Sx, conjunctivitis

• Koplik spots on buccal mucosa (white spots w/ erythematous base)

• ...followed by maculopapular rash on head —> trunk —> extremities as T cells damage virus-infected endothelial cells

• Complications: giant cell PNA, acute appy, otitis media, encephalitis



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• Togavirus (RNA)

• Forchheimer spots (red spots on posterior palate)

• Maculopapular rash lasting 3 days beginning at hairline, discrete lesions

• Painful postauricular lymphadenopathy

• Polyarthritis in adults

• Infection in first trimester may lead to congenital anomalies


Erythema infectiosum

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• Parvovirus B19 (DNA)

• Children

• Net-like erythema starting on cheeks ("slapped face" appearance)

• Polyarthritis in adults


Roseola infantum

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• HHV6 (DNA)

• Children


Varicella zoster

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• Positive Tzanck test (multinucleated giant cells)

• Children: Reye syndrome w/ ASA (encephalitis); PNA; cerebellitis

• Adults: PNA, hepatitis, encephalitis


Hand-foot-and-mouth disease

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• Coxsackievirus

• Young children

• Vesicular rash on hands, feet, mouth


Toxic shock syndrome

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• Staph aureus

• TSST toxin: superantigen

• Desquamating, sunburn-like rash


Hidradenitis suppurativa

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• Staph aureus, chronic

• Inflamed apocrine glands in axillae and groin

• Sinus tracts from abscesses



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• Often staph aureus

• Vesiculo-pustular rash begins on face, often with bullae

• Highly contagious


Scalded skin syndrome

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• Staph aureus with exfoliatin toxin

• Fever, large bullae

• Skin sloughs off, electrolytes lost

• Treat with nafcillin


Staph aureus appearance and treatment

• Gram-positive coccus in clusters

• Bactrim, vancomycin


Scarlet fever

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• Strep pyogenes

• Erythematous sandpapery rash on tongue, face—>neck—>body (spares mouth)

• White exudate w/ red papillae on tongue later fades, leaving it beefy: strawberry tongue

• Rash disappears after 6 days, desquamation for up to 10 days after

• Increased risk of post-strep glomerulonephritis


Strep pyogenes appearance

Gram-positive coccus in chains



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• Strep pyogenes

• Type of cellulitis

• Orange peel-like surface with raised borders

• Face, lower extremities

• Penicillin G for extremities, vanco for face



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• Mycobacterium leprae (can't be cultured)

• Tuberculoid type w/ intact cellular immunity: granulomas; positive lepromin skin test; localized skin lesions with nerve involvement (digital autoamputation, hypopigmented skin with anesthesia); treat with dapsone and rifampin

• Lepromatous type w/ impaired cellular immunity: many bacteria in foamy macrophages in subepidermal (Grenz) zone; negative lepromin skin test; leonine facies; dapsone, rifampin, and clofazimine


Acne vulgaris

• Chronic inflammation of pilosebaceous unit

• Inflammatory type: abnormal keratinization of follicular epithelium, increased sebum production (androgen-dependent), Propionibacterium acnes converts sebum into irritating FAs


Tinea capitis

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• Trichophyton tonsurans: most common in black population, negative Wood lamp test (infects inner hair shaft)

• Microsporum canis and audouinii: most common in whites, positive Wood lamp test

• Circular areas of alopecia

• Oral terbinafine, NOT topical azoles


Tinea corporis

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• Trichophyton rubrum

• Raised border w/ central clearing


Tinea pedis

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• Trichophyton rubrum

• Macerated scaling rash b/w toes

• Diffuse plantar scaling ("moccasin" appearance) in elderly


Tinea cruris

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• Trichophyton rubrum

• Elevated borders WITHOUT central clearing


Tinea unguium (onychomycosis)

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• Trichophyton rubrum or mentagrophytes

• Nail is raised and discolored

• Nail plate is white, thick, crumbly

• Oral terbinafine (topical azoles do NOT work)

• Onychomycosis may also be caused by candida albicans


Tinea versicolor

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• Malassezia furfur

• Hyper- or hypopigmentation

• Accentuated by Wood lamp

• "Spaghetti and meatballs" appearance on KOH mount

• Single dose of oral ketoconazole



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• Candida albicans

• Erythematous rash in body folds ("diaper rash")


Seborrheic dermatitis (dandruff)

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• Malassezia furfur

• Associated w/ Parkinson's, AIDS

• Scaly, yellowish, greasy dermatitis

• Scalp, eyebrows, nasal creases ("cradle cap" in neonates)



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• Sporothrix schenckii

• Subcutaneous

• Thermal dimorph

• Traumatic implantation (ex. rose gardening, sphagnum peat moss)

• Chain of suppurating lymphocutaneous nodules

• Treat with oral itraconazole


Cutaneous larva migrans

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• Ancylostoma braziliense (nematode)

• Dog and cat hookworm; humans are intermediate host

• Contracted by children from cat/dog waste in sandboxes

• Larvae create serpiginous tunnels in skin

• Treat with albendazole



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• Small red mite

• Papular, urticarial, or vesicular rash

• Legs and areas of tight-fitting clothes


Human itch mite (scabies)

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• Sarcoptes scabiei or hominis

• Burrows between fingers; also at wrists, nipples, scrotum

• Females lay eggs, inducing pruritis

• In adults: intertriginous areas

• In infants: no burrows; rash on palms, soles, face, or head

• Permethrin cream



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• Cimex lectularius

• Feed on human blood, active before dawn

• Allergic rxn to saliva causes wheals



• Ehrlichia chaffeensis

• Obligate intraleukocytic parasite

• Southeast, south central, mid-Atlantic US

• Reservoir in deer

• Morula (inclusion) in monocyte cytoplasm; Anaplasma species infects granulocytes

• Fever, meningoencephalitis, myalgia, rash, hepatosplenomegaly (children), edema (children)

• Treat with doxy


Solar lentigo

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• Elderly

• Brown macules on sun-exposed areas due to increased # of melanocytes



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• Black population

• Autoimmune destruction of melanocytes

• Associated w/ other autoimmune conditions



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• Women

• Macular, hyperpigmented lesions lesions on face

• Exacerbated by OCPs, pregnancy, sunlight

• Treat w/ hydroquinone (bleaching agent)


Dysplastic nevus

• May or may not develop into malignant melanoma

• >6mm, erythematous background, irregular borders

• Dysplastic nevus syndrome: >100 nevi on skin, often develop into melanoma


Malignant melanoma

• Avg age 53 yrs

• Risk factors: UV light exposure, FHx, dysplastic nevus syndrome, xeroderma pigmentosum

• Radial growth phase: proliferation within epidermis and papillary dermis, NO metastatic potential

• Vertical growth phase: penetration into reticular dermis

• Superficial spreading melanoma: 70% of cases

• Lentigo maligna: sun-exposed face, good prognosis

• Nodular melanoma: sun-exposed area, no radial growth phase, poor prognosis

• Acral lentiginous melanoma: NOT related to sun, happens on palm, sole, or nail bed, poor prognosis


Seborrheic keratosis

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• Adults >50 yrs

• Benign pigmented epidermal tumor

• "Stuck-on" appearance

• Leser-Trélat sign: rapid increase in keratoses from stomach adenocarcinoma


Acanthosis nigricans

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• Velvety, pigmented skin

• Neck, axilla, groin, under breasts

• Excess insulin



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• Males

• Crateriform tumor w/ central keratin plug grows over 4-6 weeks

• Sun-exposed area

• ? well-differentiated squamous cell carcinoma


Epidermal inclusion cyst (follicular cyst)

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• Epidermis of hair follicle

• Face, base of ears, trunk

• Produces keratin mixed w/ lipid-rich debris


Pilar cyst (wen)

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• Hair root sheath

• Scalp and face

• Cyst wall lacks stratum granulosum; keratin has laminated appearance


Fibroepithelial polyp

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• Elderly

• Skin tag on neck, upper chest, upper back


Actinic (solar) keratosis

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• Prolonged UV exposure

• Precursor of SCC

• Hyperkeratotic, pearly gray-white appearance of face, neck, dorsum of hands/forearms

• Topical 5-FU


Basal cell carcinoma

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• Chronic UV exposure

• Raised papule or nodule with central crater

• Inner canthus of eye, upper lip

• Locally aggressive, doesn't metastasize

• Multifocal in origin

• Cords of basophilic-staining basal cells on biopsy


Squamous cell carcinoma

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• Risk factors: UV light, actinic keratosis, arsenic exposure, 3rd-degree burn, chronically draining sinus tract, immunosuppression

• Scaly to nodular ulcerated lesions

• Ears, lower lip, dorsal hands

• Minimal metastasis risk

• Topical 5-FU


Ichthyosis vulgaris

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• Autosomal dominant

• Keratinization defect: absent stratum granulosum, thick stratum corneum

• Hyperkeratotic, dry skin on palms, soles, extensor areas



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• Elderly

• Decreased skin lipids



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• Acute: weeping, erythematous, vesicular rash

• Chronic: hyperkeratotic skin from scratching

• Atopic dermatitis: type I IgE hypersensitivity rxn; children: cheeks etc.; adults: hands, eyelids, elbows, knees

• Contact dermatitis: type IV hypersensitivity rxn


Chronic cutaneous lupus erythematosus

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• DNA-antiDNA immunocomplexes deposit in basement membrane

• Positive immunofluorescence

• Butterfly rash, alopecia

• Treat with antimalarials


Pemphigus vulgarus

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• IgG vs desmosomes b/w keratinocytes, type II hypersensitivity

• Vesicles and bullae on skin and oral mucosa

• Basal cells look like tombstones

• Nikolsky sign: outer epidermis easily separates from basal layer


Bullous pemphigoid

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• IgG vs basement membrane, type II hypersensitivity

• Subepidermal vesicles on skin and oral mucosa

• Negative Nikolsky


Dermatitis herpetiformis

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• IgA-antiIgA complexes (type III hypersensitivity) deposit in dermal papillae, causing subepidermal vesicles with neutrophils

• Strong association w/ celiac

• Treat with dapsone or sulfapyridine


Lichen planus

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• Pruritic, scaly, violaceous, flat-topped papules with Wickham striae; wrists & ankles

• Dystrophic nails, oral mucosa involved

• Women > men

• Slight SCC risk

• Associated with hep C



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• HLA association

• Adolescents or ~60 yr olds

• Keratinocyte hyperplasia

• Aggravated by strep pharyngitis, HIV, drugs (lithium, beta blockers, NSAIDs)

• Thickened stratum corneum w/ nuclei retention and neutrophils; elongation of rete pegs of basal layer; extension of papillary dermis close to surface epithelium

• Auspitz sign: blood vessels in dermis rupture when scales are picked off


Pityriasis rosea

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• Herald patch: single, large, oval, scaly, rose-colored plaque on trunk (can be misdiagnosed as tinea)

• Later, papular eruption on trunk ("Christmas tree" distribution

• UV light therapy hastens resolution


Erythema multiforme

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• Type IV hypersensitivity

• Triggered by Mycolplasma pneumoniae, HSV, sulfonamides, penicillin, barbiturates, phenytoin

• Targetoid vesicles and bullae on palms, soles, extensor surfaces


Stevens-Johnson syndrome

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• Type IV hypersensitivity

• Erosions of mucous membranes, blistering of skin macules


Toxic epidermal necrolysis syndrome

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• Commonly drug-induced

• Can overlap with Steven-Johnson

• Necrosis and bullous detachment of epidermis and mucous membranes —> GI bleeding, resp failure, GU complications


Erythema nodosum

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• Inflammation of subQ fat

• Raised, erythematous, painful nodules

• Associations: coccidiodomycosis, histoplasmosis, TB, leprosy, strep pharyngitis, Yersinia, sarcoidosis, ulcerative colitis, pregnancy, OCPs


Granuloma annulare

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• Chronic

• Children, adult women

• Erythematous papules —> annular plaques

• Histiocytes around mucin

• Dorsal hands and feet; dissemination may occur with DM


Porphyria cutanea tarda

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• Uroporphyrinogen decarboxylase deficiency

• Wine-red urine with uroporphyrin I

• Photosensitive bullous skin lesions (metabolite depositions), hyperpigmentation, fragile skin, hypertrichosis

• Sunlight, hep C, alcohol, OCPs, iron


Acne rosacea

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• Inflammation of facial pilosebaceous units

• Demodex folliculorum mite

• Alcohol, stress, spicy foods exacerbate

• Sebaceous gland hyperplasia w/ enlarged nose

• Treat w/ topical metronidazole or systemic isotetrinoin or tetracycline


Pyoderma gangrenosum

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• Small papule that ulcerates and enlarges; violaceous border overhangs ulcer crater

• Often associated w/ systemic disease like Crohns, myeloproliferative disease, autoimmune diseases

• Neutrophil dysfunction

• May be triggered by trauma

• Treat w/ steroids, TNF-alpha inhibitors, cyclosporine


Erythema toxicum

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• Neonates

• Benign eruptions all over EXCEPT palms and soles


Sebaceous hyperplasia

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• Neonates

• Profuse yellow-white papules



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• Neonates

• Pearly white papules containing laminated keratin material

• Face, gingiva



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• Neonates

• Retained sweat in occluded glands

• Crystallina: pinpoint clear vesicles in large eruptions; associated w/ warmth or fever

• Rubra: small erythematous papulovesicles; also responds to cooling


Mongolian spot

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• Neonates w/ dark skin

• Blue-gray spots on buttocks, back, shoulders, legs


Alopecia areata

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• Young adults

• May have autoimmune or FHx association

• Hair loss in well-circumscribed round patches over weeks

• Treat w/ clobetasol, triamcinolone