4th Exam: Skin Diseases Flashcards
Macule:
Flat, often circumscribed color difference, often red, brown, ex: measles
Papule:
Elevated, dome shaped, diameter < .5cm, ex: Lichen planus
Plaque:
Elevated lesions, flat top, larger than papules, diameter > .5cm, ex: eczema
Vesicle:
Blisters, water-filled, diameter <0.5 cm, ex: Herpes simplex
Bulla:
Larger blister than vesicles, diameter > 0.5cm, ex: bullous pemphigoid
Pustule:
Raised, yellow or white, polys in vesicles, ex: Herpes simplex
Crusting:
Vesicles or pustules break, contents dry and harden, ex: Herpes simplex
SCale:
White lesions, thickened Stratum Corneum, hyperkeratosis, ex: psoriasis, ichthyosis
Hyperkeratosis:
Thickened Stratus Corneus of keratin layer (causes SCales), ex: psoriasis, ichthyosis, actinic keratosis
Parakeratosis:
Nucleated cells in stratum corneum (normally no nuclei, keratin, dead cells), rapid proliferation of epi, ex: psoriasis
Papillomatosis:
Epidermis forms papillae, hyperplastic, ex: wart
Acanthosis:
Thickened epidermis, uniform or irregular, ex: lichen planus
Spongiosis:
Intercellular edema, vacuoles bw epi cells, cause: acute injury, ex: eczema
Acantholysis
Loss of cohesion bw keratinocytes, spaces bw cells, ex: Pemphigus
Eczema:
Nonspecific clinical term, prototype for many rashes, acute/ subacute/ chronic, red, vesicular, oozing, crusting, later: raised scaling plaques, pruritis (itchy)
Causes of Eczematous Rashes:
Contact dermatitis, atopic dermatitis/ allergy, seborrheic dermatitis, red, vesicular rash, spongiosis gives way to vesicles
Contact dermatitis causes:
Detergent, nickel, poison ivy
Rash not where the allergy is:
Atopic dermatitis/ allergy
Atopic dermatitis/ allergy:
Often kids, cause unknown, genetic in some cases, stimulus: food or clothing?, Pt often has asthma, allergic rhinitis, often chronic w acute episodes
Seborrheic dermatitis:
Stasis dermatitis (sluggish leg veins), drug reaction, type of eczematous rash, common, 5-10% of healthy, 1/3rd of AIDS pts, chronic, waxing and waning, hairy regions, esp face, eyebrows, scalp, around sebaceous glands, bilateral, symmetrical, itching variable, lipophilic yeast, Pityrosporum ovale, mildest form: dandruff; fine white scale, may have erythema, patches/plaques
Tx for Seborrheic dermatitis:
Anti-fungal, shampoo 2-3 X wk, zinc pyrithione (Head and Shoulders), selenium sulfide, ketoconazole
Inflammatory Scaling Papule & Plaques:
Dermatophytes, psoriasis, pityriasis rosea, 2’ syphilis, lichen planus
Pityriasis rosea:
“bran-like scale”, young adults, seasonal, usually winter, often URI before, cellular Type IV immune response, antigen unknown, acute, self-limited, mostly trunk, neck
Pityriasis rosea rash:
Herald patch (initial rapidly enlarging oval-shaped red papulosquamous lesion, usually trunk, heralding widespread eruption of pityriasis rosea in 7-14d), first, often largest, many lesions after several days, round to oval, tan/salmon color, look like bran/ corn flakes, itching is common, delicate scaling, elevated patches
Ddx of Pityriasis rosea:
Psoriasis, lichen planus, tinea corporis (ringworm), 2’ syphilis
Tx for Pityriasis rosea:
Usually spontaneous remission in 2-4wks, recurrence rare
Lichen planus:
Cause unknown, probably immune-mediated, more common in women, Ig deposits at dermal-epidermal jx, some cases assoc w Hep C, involves skin & mucous membranes, oral lesions, 70% pts, esp. wrist and ankle, oral manifestation: red gum tissue, multiple lesions, purple, planar (flat) or papular, polygonal, pruritic (itchy), self-limited, resolves in mos-2yr, multiple papules w Wickham striae (whitish lines visible in papules of lichen planus and other dermatoses, typically the macroscopic appearance of the histologic phenomenon hypergranulosis), white dots = thickened granular layer
Histology of Lichen planus:
Hyperkeratosis, thickened granular layer (almost diagnostic), irregular acanthosis (saw tooth D-E jx), band-like lymphocytic infiltrate (degeneration of basal layer)
Vesicles of Lichen planus are often:
exanthems
exanthems:
widespread rash usually occurring in children
Possible causes of exanthems:
Varicella, herpes simplex, herpes zoster, enterovirus
bullous/vesicular skin diseases (large, fluid filled)
hard or flaccid:
Pemphigus vulgaris, bullous pemphigoid, dermatitis herpetiformis (DH), porphyria, contact dermatitis, drug reaction/eruption, impetigo, scalded skin syndrome
Pemphigus vulgaris:
Middle aged+, generalized bullae, anywhere on skin surface, oral lesions common, bullae flaccid, 1-10 cm, rupture easily → bleeding erosions → skin infection, mortality 8-10%, INTRAepidermal, suprabasilar bullae, only disease to have suprabasilar → DIAGNOSTIC, Begins w acantholysis, intercellular IgG, C3, autoantibodies to desmoglein 3 (adhesion molecule), Ab titer predicts course
Tx for Pemphigus vulgaris:
Steroids
only disease to have suprabasilar, DIAGNOSTIC:
Pemphigus vulgaris
acantholysis:
loss of intercellular connections such as desmosomes resulting in loss of cohesion bw keratinocytes, not seen in bullous pemphigoid
Autoantibodies to desmoglein 3:
located in desmosomes, Anti-desmoglein 3 Ab → Intercellular fluorescent deposits
Bullous pemphigoid:
50-70yo, bullae in flexor areas (groin, axilla), ral lesions: 1/3 pts, very pruritic, tense bullae, 1-5 cm, heals wo scar, most subside in mo-1yr, subepidermal bullae, linear IgG, C3 at BM (lamina lucida), autoantibodies to hemidesmosome proteins, BP 180 and BP 230, intracellular and lamina lucida location, Ab binding to Ag seen in skin BM (LL – lamina lucida, LD - lamina densa), immunofluorescent deposits at BM (Only at the DE junction), like lichen planus, DM, SLE
Rx for Bullous pemphigoid:
steroid, like pemphigus vulgaris
Porphyria cutaea tarda:
Abnormal porphyrin metabolism (urodecarboxylase missing in cutaneous porphyria), most common porphyria, familial, autosomal dominant, uroporphyrinogen decarboxylase deficiency → build up of porphyrins, Dark brown urine; ↑ uroporphyrin, lesions precipitated by alcohol, sunlight, photosensitive skin lesions, esp hands (dorsum)
Photosensitive skin lesions, esp hands (dorsum)
Subepi bullae, excess hair, esp forehead, temples, cheeks, neck
Recap of pemphigoid:
tense bullae, subepidermal, Ig at BM, hemidesmosomes
Recap of pemphigus:
flaccid ullae, suprabasillar, Ig are intracellular, desmoglein 3
Recap of porphyria CT:
Tense bulla, subepidermal, Ig at De jx, absent UPDC
These both have tense bullae and are subepidermal:
pemphigoid, porphyria
Generalized erythema:
Drug eruption, Viral, Toxic, SLE, DM
Viral, generalized erythema may be due to:
Rubella, measles, Roseola (HHV6), erythema infectiosum (parvo B19)
Toxic, generalized erythema may be due to:
Scarlet fever-GAS, fever, pharyngitis (erythrogenic exotoxin, rash on face (circumoral pallor), arms, legs, trunk), scalded skin-Staph toxin, infants, fever, toxic shock syndrome-Staph and GAS
Localized lesions w erythema:
Cellulitis, erysipelas-GAS, face, well-demarcated, fever, acute, swelling (type of cellulitis), rapid progression, impetigo- Staph/GAS, preschool children, face & neck, erythema nodosum, erythema multiforme, erythema migrans-Lyme disease
Erythema nodosum:
Assoc w infections/immune mediated disease, type of panniculitis (subcutaneous), acute presentation (fever, malaise), often self-limited, but may be recurrent, rash: often lower legs (multiple, deep, tender nodules)
infections/immune mediated disease assoc w erythema nodosum:
TB, sarcoidosis, IBD, beta strep infections
panniculitis:
subcutaneous, below the skin- looks like a skin disease, but isn’t
Tx for Erythema nodosum:
aimed at underlyling disease
Early histo findings of Erythema nodosum:
polys, fibrin, deposits of Ig and C
Semi-progressed histo findings of Erythema nodosum:
granulomatous inflammation, looks like TB
Late histo findings of bands of Erythema nodosum:
bands of fibrosis
Erythema nodosum is marked by chronic inflammation w this cell type:
giant cell
Erythema mulitforme causes:
o Drugs • Sulfonamides, penicillins, salicylates o Infection, esp herpes simplex o Cancer o Collagen disease o Idiopathic
Pathogenesis of Erythema mulitforme:
- Epidermal cells killed by T cells
* Cytotoxic CD8+ lymphocytes located at D-E jx
population most affected by Erythema mulitforme:
older children, young adults
Lesions of Erythema mulitforme:
Symmetrical, often extremities, classically look like a target (erythematous rim and center- diagnostic/signature lesion (esp if on extremities) )
Histology of Erythema mulitforme:
Red, round, circumscribed, target-like, multiple, lymphocytes at D-E jx (migrate into epidermis, attack keratinocytes)
