Skin Path (Gomez)- Part 2 Flashcards
Acute Urticaria types
Hives
- Mast cell and IgE dependent
- - Acute allergic reaction (minutes) – medical emergency
- - Severe discomfort; profound itching - Mast cell dependent but IgE independent
- - Drug (#1) or other substance triggers mast cells directly (opiates, contrast media) - Mast cell and IgE independent
- - Aspirin induced vasodilation
- - Hereditary angioneurotic edema (C1-inhibitor deficiency)
** All types can cause fatalities
- Systemic anaphylaxis
- Laryngeal edema
- Rx- antihistamines, subcutaneous epinephrine and IM corticosteroids
(With known C1 inhibitor deficiency use C1 inhibitor (C1-INH) concentrates, kallikrein inhibitor or fresh-frozen plasma)
Acute Urticaria - what’s going on
Inciting agent may be known but * frequently inciting agent is not known
- Bee/wasp stings
- Allergic reaction drugs (penicillin, ASA, etc.)
Abrupt appearance of intensely pruritic * wheals +/- bullae
- Wheal: Transient edematous erythematous * plaque secondary to an acute allergic reaction
- Bullae: Larger fluid-filled lesions
Commonly involves trunk and extremities
Usually resolves 24 hrs.
- May persist days, even months
Eczema
=Spongiotic Dermatitis
- Intercellular epidermal edema and prominent lymphocytes in dermis and epidermis
Usually driven by T cell mediated * type IV hypersensitivity inflammation
Includes numerous pathologic and clinical conditions
Usually an acute onset of red, papulovesicular lesions (“boiling over” appearance) which may ooze or crust
Acute lesions may evolve into raised, scaling plaques
Erythema Multiforme
- Hypersensitivity (CD8+ cytotoxic T cells) reaction to
- Infections: * herpes simplex, * deep fungal (histoplasmosis), * Salmonella typhi, * leprosy
Drugs: * antibiotics, * salicylates, * anti-malarials
Malignancy
Collagen vascular disorders - “Multiforme” = wide variety of clinical appearances in addition to characteristic * “target” lesions (red-pale-red)
Pathophysiologically similar conditions
to Erythema multiforme
- Stevens-Johnson syndrome: Severe, systemic disease with atypical targetoid skin lesions that become bullous +/- oral and ocular involvement
- Toxic epidermal necrolysis: has diffuse necrosis and sloughing of skin and mucosae
Erythema Multiforme vs Urticaria
opposite; erythema has central blister/ necrosis surrounded by variable redness
urticaria has central clearing from edema
Psoriasis
Systemic disease causing a chronic skin condition
- Typical lesion: well-demarcated, pink to salmon plaque
- Involves elbows, knees, scalp, lumbosacral area, intergluteal cleft, and glans penis
- Koebner phenomenon – trauma can induce skin lesions
- Auspitz sign – scrape off scale and get punctate hemorrhages
- May involve nails
- Can involve other organs (e.g. psoriatic arthritis)
Lichen Simplex Chronicus
From chronic rubbing or scratching
If nodular = Prurigo nodularis
Seborrheic Dermatitis
Common chronic dermatitis (5% of population)
- Skin with high density of sebaceous glands
- Scalp, forehead, especially glabella (space between eyebrows), nasolabial folds, auditory canals, intergluteal fold
- Excessive dandruff on scalp common
Infection with superficial yeast (* Malassezia furfur) may play important role since condition is improved by use of topical antifungal agents
Lichen Planus
Self-limiting chronic inflammatory condition of * skin and oral mucous membranes
Multiple plaques that are symmetrically distributed, often on wrists and elbows and on the glans penis, *+ Koebner phenomenon
Usually resolves 1-2 years after onset, but may persist for years in oral cavity
Cutaneous Lupus Erythematosus (CLE)
- Localized cutaneous manifestations similar to those of systemic lupus erythematosus (SLE) but with * no SLE systemic manifestations
If only symptoms and signs are CLE then usually will not develop systemic symptoms and signs of SLE - 1/3 of all SLE patients will have cutaneous findings identical to those found in CLE (e.g. discoid lupus erythematosus)
- Major Cutaneous Findings: Excessive sun exposure may trigger cutaneous lesions or exacerbate them
- Malar erythema (also a characteristic of SLE)
- Chronic subtypes
– Discoid - coin-like scaling plaques
– Tumid – juicy red papules and plaques
– Lupus panniculitis/profundus – painful
subcutaneous nodules
what does lupus erythematosis look like?
Chronic plaques show thinned glistening (atrophic) epidermis & areas with dilated, tortuous dermal vessels
Note the central hypopigmentation surrounded by peripheral hyperpigmentation
microscopic: Granular deposits of antigen-antibody complexes and complement at
dermoepidermal junction constitute a positive “band test”
Rosacea
Fairly common in 30-60 y/o females Stages - Pre-rosacea (flushing) - Erythematotelengiectatic - Papulopustular * Phymatous
Pathophysiology uncertain
Numerous triggers
Perifollicular inflammation with changes similar to acne vulgaris microscopically
Blistering (Bullous) Diseases
common friction blister
imune-mediated
genetic-congenital
Common friction blister
Intraepidermal blister usually just beneath the stratum granulosum with scant or no inflammation in papillary dermis.
Immune-mediated blistering diseases
Pemphigus group of diseases
Bullous pemphigoid
Dermatitis herpetiformis
Genetic-congenital
blistering diseases
Epidermolysis bullosa- inherited defects in collagen, laminin, etc leading to several disorders with weak skin and blistering
Porphyrias
Blistering (Bullous) Diseases
Detachment sites and blister types
Detachment at:
Superficial desmosomes →
subcorneal blister
Deeper desmosomes →
suprabasal blister
Hemidesmosomes →
subepidermal blister
Blistering diseases: Adhesion Molecules Attacked
Attack at:
Superficial desmosomes Desmoglein 1 →
Pemphigus foliaceus
Deeper desmosomes
Desmogleins 1 & 3 →
pemphigus vulgaris
Hemidesmosomes BPAG1 and BPAG2 → Bullous pemphigoid or Reticulin in anchoring fibers→ Dermatitis herpetiformes
Pemphigus Group of Diseases
Autoimmune skin diseases
* IgG autoantibody to desmosomes of squamous epithelial cells
Five clinical and pathologic types
- Pemphigus vulgaris (80%): Involves mucosa and scalp, face, axilla, groin and other pressure points; classic bullous disease
- Pemphigus foliaceus: more benign course; involves face, scalp, chest and back and spares mucous membranes
Epidemic form occurs in South America (fogo salvagem)
- Pemphigus erythematosus: mild localized form of foliaceus which involves primarily malar area of face
- Pemphigus vegetans (rare): verrucous plaques instead of blisters involving axilla, groin, and flexural surfaces
- Paraneoplastic pemphigus: occurs with malignancies (lymphoma)
Pemphigus Foliaceus- what do we find?
Dsg1 in superficial desmosomes
more benign course; involves face, scalp, chest and back and spares mucous membranes
Pemphigus Vulgaris
- what we find
Dsg1 & Dsg3 in all desmosomes
Bullous Pemphigoid- what we find
BPAG1 & BPAG2 in hemidesmosomes
- Autoantibody to hemidesmosomes
- Subepidermal blister
- more resistant to rupture than pemphigus
Dermatitis Herpetiformis
IgA to gliadin attacks reticulin in dermal papillae fibrils
- Rare skin bullous disorder
M>F
Onset in 3rd and 4th decades - Major association with celiac disease (non-tropical sprue, gluten-sensitive enteropathy)
*- Anti-gliadin antibodies cross-react with reticulin in the anchoring fibrils in dermal papillae - Intensely pruritic plaques and vesicles
Extensor surfaces, elbows, knees, upper back and buttocks
