Skin I (a) Flashcards
Causes of Urticaria
Pollens, foods, drugs, and insect venom
Epi of Urticaria
20-40 yrs of age
Patho of Urticaria
Immediate (type 1) hypersensitivity reaction -> corss-linkage of IgE on mast cells which cause degranualtion
Microscopic Findings:
* Superficial perivenular infiltrate of mononuclear cells (Lymphatic vessel dilatation)
* Superficial dermal oedema, creating more widely spaced collagen bundles
* Degranulation of mast cells,
features of?
Urticaria
Degranulation of mast cells in Urticaria can highlighted using ——– stain
Giemsa stain
CP of Urticaria
Erythematous, oedematous, and Pruritic wheals(form after the degranulation of mast cells)
Tx of Urticaria
Antihistamines, systemic steroids
pressure Urticaria are lesions found only in areas exposed to ——–?
pressure
Heriditray Angioedema is caused by what type of deficiency?
C1 esterase inhibitor
Hereditary Angioedema affects?
1) lips,
2) throat,
3) eyelids,
4) genitals, and
5) distal extremities
CP of Acute Eczematous Dermatitis (Eczema)
Oozing/ crusted Red papules, often with overlying vesicles
Causes of Acute Eczematous Dermatitis (Eczema)
1. Allergic Contact Dermatitis (most common): Topical exposure to allergen
2. Atopic Dermatitis: Allergen exposure or defects in keratinocyte barrier function
3.Drug-related Eczematous Dermatitis: Hypersensitivity reaction to a drug
cause of Allergic Contact Dermatitis
Type IV hypersensitivity reaction secondary to contact allergens (e.g, poison ivy, nickel)
patho of Allergic Contact Dermatitis
Contact of allergen (poisin ivy) w/ skin –>
CP of allergic contact dermatitis
localized pruritic (itchy) skin lesions, blisters w/ clear fluid
* bullae: blisters w/ clear fluid
Microscopic Findings:
* Spongiosis (epidermal odema)
* Intercellular bridges are stretched
* Superficial perivascular lymphocytic infiltrate
* Oedema of dermal papillae
* Mast cell degranulation
features of?
Allergic Contact Dermatitis
*note very similar micro features of Urticaria
Cause of Erythema Multiforme
Hypersensitivity response to:
* Infections(Herpes Simplex Virus and Mycoplasma)
* Drugs (Sulfonamides, Penicillin, Salicylates, Hydantoins, Antimalarials)
*pathophysio
In Erythema Multiforme Skin-homing Cytotoxic T-cells attack the ———- of the skin and the ————, which may display antigens that cross-react with the inciting drug or microbe
Basal cells, mucosa
CP of Erythema Multiforme
Target- like papules
(consisting of red macules or papules with pale vesicular or eroded centers)
**
Macroscopic features:
* pathces have pale, vesicular, or eroded centers (Target-like papules)
Microscopic Findings:
* Dermal oedema
* lesions w/ degenerating (apoptotic) keratinocytes w/ lymphocytic infiltrates
Erythema Multiforme
*keratinocytes: the major cell type of the epidermis
2 severe forms of Erythema Multiforme
Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis
cause of Psoriasis
* chronic skin inflammatory disorder
Multifactorial immunologic disease, in which both genetic (e.g. Human Leukocyte Antigen [HLA] types) and environmental factors contribute to risk
Patho of Psoriasis
Sensitised populations of T cells secrete cytokines and growth factors that induce keratinocyte hyper- proliferation
CP of Psoriasis
pink to salmon-coloured palques w/ silvery scaling
Microscopic Findings:
* Epidermal thickening (acanthosis), w/ parakeratotic (nuclei still in stratum corneum)
* loss of the stratum granulosum and parakeratotic scale (due to lack of maturation)
* Regular elongation of the rete ridges
* Thinning of the epidermal cell layer overlying the tips of dermal papillae
Features of?
Psoriasis
patho of Linchen PLanus
* chronic inflammatory skin disorder
CD8+ T cell-mediated cytotoxic immune response against antigens in the basal cell layer and the dermo-epidermal junction
Epi of Lichen Planus
Uncommon disorder; Middle-aged adults
**
CP of Lichen Planus
6 P’s
1) Pruritic, purple, polygonal, planar papules, and plaques of skin and squamous mucosa
2) Mucosal involvement –> Wickham striae
**
Microscopic Findings:
* The lymphocytes are intimately associated with basal keratinocytes, which often atrophy or become necrotic
* “zig-zag” contour/”saw-tooth” infiltrate of lymphocytes at Dermo-epidermal interface (junction)
* Presence of anucleate, necrotic basal cells (colloid bodies or Civatte bodies)
features of?
Lichen Planus
cause of Lichen simplex Chronicus
Response to local repetitive trauma, such as continual rubbing or scratching