Inflammatory Lesions Flashcards
What is ichthyosis?
(appearance and histologic features)
impaired epidermal maturation
- hyperkeratosis
- dry, coarse “fish-like” scales
Where and in what populations is ichthyosis most commonly seen?
-extensor surfaces
Inherited: first year of life, usually resolving around adolescence
Aquired: as a paraneoplastic syndrome
What is urticaria?
(appearance and histologic features)
hives/wheals
- transient, pruitic, edmatous papules/plaques
- angioedema: swelling of dermis and subcutaneous fat
- dermal edema
- epidermis unchanged
What are the mechanisms of urticaria?
Mast cell degranulation:
- IgE dependent; type I hypersensitivities/allergies/anaphylaxis
- IgE independent; substances that stimulate degranulation directly
What is acute eczematous dermatitis?
(appearance and histologic features)
- red papular/vesicular, oozing, crusted lesions
- scaling plaques if persistent
Acute lesions
- spongiosis (edema of the epidermis)
- acantholysis (seperation of keratinocyte -> vesicle formation)
Persistent lesions
- acanthosis (diffuse epidermal hyperplasia)
- hyperkeratosis
What is the mechanism of acute eczematous dermatitis?
Type IV hypersensitivity
-requires sensitization
-delayed reaction following stimulus
What is erythema multiforme?
(appearance and histologic features)
self-limited T-cell mediated, hypersensitivity
- various lesions types (hence multiforme), classically erythematous macule -> papule -> targetoid lesion
- infiltrating lymphocytes
- areas of epidermal necrosis
Where and in what populations is erythema multiforme most commonly seen?
- typically start on hands/feet and extend proximally
- young/middle aged adults (20-40 years)
What are common causes of erythema multiforme?
Infection
- herpes simpex
- mycoplasma
- histoplasmosis
- coccidiodomycosis
- typhoid
Drugs:
- penicillins
- sulfonamides
- antimalarials
Certain cancers
Autoimmune diseases
What is Stevens-Johnson syndrome?
Complication of erythema multiforme
- targetoid lesions of erythema multiforme
- fever*** (differentiating feature)
- involvement of <10% surface area
- involvement of mucous membranes
- sloughing of skin -> fluid loss -> shock
What is toxic epidermal necrolyis (TEN)?
Severe form of Stevens-Johnson syndrome
- fever
- targetoid lesions of erythema multiforme
- involvement of >30% surface area*** (differentiating feature)
- involvement of mucous membranes
- sloughing of skin -> fluid loss -> shock
What is psoriasis?
(appearance and histologic features)
Chronic inflammatory dermatosis
- associated with mild to severly deforming arthritis
- pink to salmon-colored plaque with adherent silver-white scale
- pruritic
- nail involvement (pitting or separation/onycholysis)
- acanthosis (epidermal hyperplasia)
- elognated rete ridges
- Munro microabscesses (neutrophils in stratum conreum)
- parakaratosis
Where and in what populations is psoriasis most commonly seen?
- extensor surfaces
- young/middle aged adults (20-40 years)
What are characteristic/diagnositic features of psoriasis?
Koebner phenomenon:
- physical stimuli (scratching, irritation, or trauma) produces lesion
- lesions are pruritic which can cause propagation of lesions
Auspitz sign:
-removal of scale results in pinpoint bleeding
What is the treatment for psoriasis?
-corticosteroids
PUVA
-Psoralen with UVA
What is seborrheic dermatitis?
(appearance and histologic features)
Chronic inflammatory dermatosis
- dandruff is a form
- erythematous papules on erythematous base with scales and greasy yellow crusts
-parakaratotic mounds
-follicular lipping
Where and in what populations is seborrheic dermatitis most commonly seen?
Oily skin (numerous sebaceous glands)
- forehead, around the ears, nasolabial fold, presternal
- more common in men (androgens?)
- bimodal; infants and puberty
What conditions are associated with development of seborrheic dermatitis?
- Malassezia colonization
- adrongens (increased sebum)
- Parkinson’s disease
- HIV w/ low CD4 count
What is lichen planus?
(appearance and histologic features)
Chronic inflammatory dermatosis
six “P’s”
- pruritic
- purple
- polygonal
- planar (flat top)
- papules
- plaques
Wickham striae: white lines on surface of lesion
- hyperkeratosis
- hypergranulosis (-> Wickham striae)
- saw-tooth acanthosis
- band-like lymphocyte infiltrate of dermal-epidermal junction
Where is lichen planus most commonly seen?
Symmetrically on extremities
-wrists, elbows, and ankles
Mucosa
What condition is associated with development of lichen planus?
chronic hepatitis C infections
What cancer is associated with lichen planus?
squamous cell carcinoma of chronically infected mucosa
What is pemphigus?
(mechanism, appearance, and histologic/immunofluorescence features)
Blistering disease
- IgG autoantibodies against desmogleins (in desmosomes)
- vesicles/bullae -> rupture to form erosions and crusts
- non-pruritic
- acantholysis (above the basal layer)
- “tombstone” appearance; basal layer attached to basement membrane
- fishnet-like immunofluorescence surrounding keratinocytes
Where and in what populations is pemphigus most commonly seen?
- older adults (40-60)
- first appear in oral mucosa, later in intertriginous areas
What is a characteristic clinical finding of pemphigus that helps to differentiate it from other blister disorders?
Nikolsky’s sign:
-thin vesicle/bullae (they are intraepidermal and more superficial) readily rupture -> erosions and crusts
What is bullous pemphigoid?
(mechanism, appearance, and histologic/immunofluorescence features)
Blistering disease
- IgG autoantibodies against BPAg (in hemidesmosomes)
- tense bullae, don’t rupture
- pruritic
-subepidermal, nonakantholytic
-linear immunofluorescence along basement membrane
Where and in what populations is bullous pemphigoid most commonly seen?
- inner thigh, flexor surfaces, axilla, groin
- RARE mucosal involvement
- elderly (over 60)
What is dermatitis herpetiformis?
(mechanism, appearance, and histologic/immunofluorescence features)
Blistering disease
- IgA autoantibodies against gluten analog in epidermal basement membrane
- tense, grouped vesicles (herpetiform)
- extremely pruritic
- subepidermal blister at tip of dermal papillae
-noncontinuous immunofluorescence at tip of dermal papillae
Where and in what populations is dermatitis herpetiformis most commonly seen?
- extensor surfaces
- NO mucosal involvement
- middle aged adult males (30-40)
What condition is associated with development of dermatitis herpetiformis?
celiac disease, autoantibody is against gluten like substance in basement membrane
What is the treatment for dermatitis herpetiformis?
gluten free diet
What is epidermolysis bullosa?
(mechanism and onset)
Non-inflammatory, inherited blistering disease
- blisters easily form from mechanical stress
- onset at birth
What are porphyrias and how do they relate to the skin?
(mechanism)
Inherited defects in porphyrin synthesis
- deposition of intermediates into skin can occur -> fragile skin -> blisters
- subepidermal vesicles, scar when ruptured
- worsens with sun exposure
What is acne vulgaris?
(appearance and histologic features)
- erythematous papules, nodules, or pustules
- may have open or closed comedones, white/black heads (keratin plug either visible or below epidermal surface)
What are causes of acne vulgaris?
- keratinization of follicle -> keratin plug
- hypertrophy of sebaceous glands (androgens in puberty)
- Propionibacterium acnes colonization of follicle
What is the treatment for acne vulgaris?
- benzoyl peroxide (antimicrobial)/antibiotics
- vitamin A derivatives
What is rosacea?
(appearance and histologic features)
- facial flushing
- persistent erythema w/ telangiectasia
- pustules/papules
- rhinophyma (thickend nasal skin by papules)
What is the mechanism of rosacea?
-increased levels of cathelicidin (antimicrobial peptides)
Where and in what populations is rosacea most commonly seen?
- face, particularly around the nose
- more common in women
- mid-older adults (30-60)
What is paniculitis?
inflammation of subcutaneous adipose
What is erythema nodosum?
(appearance and histologic features)
Panniculitis (subcutaneous adipose inflammation)
- firm, tender, erythematous nodules
- more noticeable by palpation than inspection
- subcutaneous edema and infiltration
What is erythema induratum?
(appearance and histologic features)
Panniculitis (subcutaneous adipose inflammation)
- tender, erythematous nodules
- ulcerate
- subcutaneous granulomas/necrosis
What are verrucae?
(appearance and histologic features)
Warts (HPV infection)
- skin colored papules
- epidermal hyperkeratosis/hyperplasia
What is molluscum contagiosum?
(appearance and histologic features)
caused by Pox virus
- skin colored papule with umbilication
- Molluscum bodies
What is impetigo?
(appearance and histologic features)
Staphylococcus aureus (bullous) or Strep A (non-bullous) infection of the skin
- erythematous macules -> pustules
- honey-colored crust
- neutrophil infiltration under stratum corneum -> pustules
