Fung: Dermatopathology Flashcards
What are the four layers of the epidermis from the basement membrane to the surface?
stratum basale
stratum spinosum
stratum granulosum
stratum corneum
Which layer of the epidermis has keratohyalin granules?
stratum granulosum
What are two cell types in the epidermis? What do these cells do?
- melanocytes: protect the skin from UV injury
2. Langerhan cells: antigen recognition and immune response
What are two layers found in the dermis?
papillary vs reticular layer
What is found in the dermis?
sebaceous glands, apocrine, and eccrine glands too
How do the palms of the hands and soles of the feet differ in terms of their epidermal layer?
thicker layer of keratin bc these areas undergo a lot of trauma and sheering forces daily
Circumscribed, flat lesion <5mm distinguished from surrounding skin by color
macule
Circumscribed, flat lesion >5mm distinguished from surrounding skin by color
patch
Elevated dome-shaped or flat-topped lesion <5mm
papule
Elevated dome-shaped or flat-topped lesion >5mm
nodule
Elevated flat-topped lesion >5mm
plaque
discrete, pus-filled, raised lesion
pustule
dry, horny, platelike excrescence, usu the result of imperfect cornification
scale
fluid-filled raised lesion <5mm, also called a blister
vesicle
fluid-filled raised lesion >5mm; also called a blister
bulla
traumatic lesion breaking the epidermis and causing a raw linear area
excoriation
itchy, transient, elevated lesion with variable blanching and erythema formed as the result of edema
wheal
thickened, rough skin; usu the result of repeated rubbing
lichenification
What’s the difference bw a vesicle and a bulla?
a vesicle is 5mm
What is a notable feature of a wheal?
blanching
diffuse epidermal hyperplasia
acanthosis
abnormal, premature keratinization w/i cells below the stratum granulosum
dyskeratosis
hyperplasia of the stratum granulosum
hypergranulosis
thickening of the stratum corneum
hyperkeratosis
a linear pattern of melanocyte proliferation w/i the epidermal basal cell layer
lentiginous
surface elevation caused by hyperplasia and enlargement of contiguous dermal papillae
papillomatosis
keratinization w retained nuclei in the stratum corneum
parakeratosis
intercellular edema of the epidermis
spongiosis
Where is hyperkeratosis seen?
in the palms and soles of the feet
What is the difference between hyperkeratosis and parakeratosis?
hyperkeratosis: thick layer of keratin above the granulosum
parakeratosis: thick layer of keratin, but it retains the nucleus
What is the difference between acanthosis and papillomatosis?
both are epidermal hyperplasia, but papillomatosis produces distinct papillary fragments
In spongiosis, what happens to the cells due to the intracellular edema?
they get pushed apart
Where is dyskeratosis seen?
within cells BELOW the stratum granulosum
Last from days to weeks
Characterized by lymphocytic and macrophage inflammatory infiltrate and edema
acute inflammatory dermatoses
Persist for months to years
Associated with changes in epidermal growth (atrophy or hyperplasia) or dermal fibrosis
The skin is roughened due to excess or abnormal scale formation and shedding
chronic inflammatory dermatoses
Common disorder characterized by localized mast cell degranulation and dermal microvascular hyperpermeability
Patients present with pruritic edematous plaques (wheals)
Angioedema is a related condition with edema of the deeper dermis and subcutaneous fat
Can be acute (less than 6 weeks) or chronic
urticaria
How do patients with urticaria present?
w pruritic (itchy) edematous plaques (wheals)
Urticaria is a common disorder characterized by localized (blank) degranulation and dermal microvascular (blank)
mast cell; hyperpermeability
In urticaria (hives), which layer of the skin will have edema and sparse inflammation?
papillary dermis
Causes of urticaria?
immunological mechanisms non-immuno mechanisms physical stimuli skin contact small vessel vasculitis
Treatment for urticaria?
avoid specific allergens oral H1 (histamine) antagonists epi
One of the most common skin disorders
Can be subdivided into 5 categories
Results from T-cell mediated inflammatory reactions (type IV hypersensitivity)
acute eczematous dermatitis (eczema)
What type of immune reaction occurs in eczema?
T-cell mediated inflammatory reaction (type 4 hypersensitivity)
What will you see microscopically in cases of eczema?
spongiosis
intraepidermal vesicles
hemorrhage
lymphocytes invading
What causes eczema?
internal or external antigen
Treatment for eczema?
remove offending agent
topical steroids
Self-limited hypersensitivity reaction Associated with infections from Virus: Herpes simplex Bacteria: Mycoplasma, leprosy, typhoid Fungus: Histoplasma, Coccidioides Exposure to drugs: sulfonamides, penicillin, barbiturates, salicylates, antimalarials Cancer Collagen vascular disease
Erythema multiforme
How does erythema multiforme present clinically?
with classical target-oid lesions with crust in the center; different shapes and sizes of lesions
How does erythema multiforme look microscopically?
spongiosis
dermal edema
necrotic keratinocytes
parakeratosis
A febrile form of erythema multiforme with extensive skin involvement
Also involves oral mucosa, conjunctiva, urethra, genital and perianal areas
May lead to sepsis
Often seen in children
Stevens Johnson syndrome
A form of erythema multiforme
Characterized by diffuse necrosis and sloughing of cutaneous and mucosal epithelial surfaces
Clinical picture similar to that of burn patients
Toxic epidermal necrolysis
Treatment for erythema multiforme?
observe oral antihistamines topical steroids acyclovir (herpes simplex) prednisone
chronic: antibiotics
Common disorder affecting 1-2% of the US population
Chronic inflammatory dermatosis that results from interactions of genetic and environmental factors
Associated with HLA-C
Results from activated T cells in the skin stimulating the secretion of cytokines and growth factors that induce keratinocyte proliferation
15% of patients have associated arthritis
psoriasis
What kind of immune reaction is occurring in psoriasis?
activated T cells in the skin stimulate cytokines and growth factors that induce keratinocyte proliferation
What might patients with psoriasis also present with?
arthritis
What does psoriasis look like microscopically?
acanthosis in epidermis spongiosis lymphocyte invasion can have suprapapillary thinning spongiform pustules
Treatment for psoriasis
topical steroids
intralesional steroid injection
UVB and tar
drugs
Common chronic inflammatory dermatosis that affects up to 5% of the general population
Involves regions with high density of sebaceous glands
Scalp Forehead External auditory canal Retroauricular area Nasolabial folds Presternal area
Seborrheic dermatitis
What are two causes of sebhorreic dermatitis?
increased sebum production
colonization of the skin by Malassezia (fungus)
Severe form of sebhorreic dermatitis seen in (blank) patients with low CD4 count
HIV+
Treatment of sebhorreic dermatitis?
frequent washing of the affected area with antisebhorreic soaps
topical steroids
anti-yeast meds
oral antifungals
Self-limited condition most commonly resolving spontaneously 1-2 years after onset
“Six Ps”
Pruritic, purple, polygonal, planar, papules and plaques
Resolution of lesions may leave postinflammatory hyperpigmentation
Squamous cell carcinoma may develop in oral lesions
Lichen planus
What does lichen planus look like microscopically?
contact hyperkeratosis
hypergranulosis
lichenoid lymphocytes (thick band of lymphocytic infiltration of dermal/epidermal junction)
Treatment for lichen planus?
topical steroids intralesional steroids systemic steroids drugs light therapy
(blank) disorders are a group of diseases in which blisters are the primary and most distinctive feature
bullous
4 conditions in which blisters are a feature
herpes virus
spongiotic dermatitis
erythema multiforme
thermal burns
3 types of blistering disorders
subcorneal (beneath the stratum corneum)
suprabasal (above the stratum basale)
subepidermal (beneath the epidermis at the level of the basement membrane)
Corneal blisters affect which protein in the skin?
desmoglin 1
Superbasal blisters affect which protein in the skin?
desmoglin 3
In inflammatory blistering disorder caused by autoantibodies that result in the dissolution of intercellular attachments within the epidermis and mucosal epithelium
IgG autoantibodies to desmoglein 1 and 3 disrupt intercellular adhesions of desmosomes
pemphigus
This form of pemphigus accounts for 80% of cases
pemphigus vulgaris
This form of pemphigus is rare and forms plaques around the groin
pemphigus vegetans
This form of pemphigus forms subcorneal blisters
pemphigus foliaceus
What is unique about the blisters in pemphigus?
they crust and break open
Treatment of pemphigus
immunosuppressive agents to decrease the titers of the pathogenic antibodies
In pemphigus, the body forms autoantibodies to what? What does this cause?
desmoglin 1 and 3; disruption of intercellular adhesions of desmosomes
A blistering disorder caused by autoantibodies directed to the proteins that bind basal keratinocytes to the basement membrane
Antibody deposition occurs in a linear pattern at the dermoepidermal junction
The proteins BPAGs are part of the hemidesmosomes that link basal keratinocytes to the basement membrane
bullous penphigoid
In bullous pemphigoid, what is the body making autoanitbodies to?
BPAG - proteins that bind basal keratinocytes to the basement membrane
What is one characteristic feature of bullous pemphigoid?
subepidermal blister (the whole epidermis is raised above the blister)
What can be used to detect bullous pemphigoid?
immunofluorescence to look for linear IgG on the roof of the blister
What is a characteristic immunofluorescence feature of pemphigus?
swiss cheese pattern of intra-epidermal IgG
Treatment of bullous pemphigoid?
topical steroids
systemic steroids
drugs
Rare disorder characterized by urticaria and grouped vesicles
Strong association with HLA-B8, HLA-DR3 and HLA-DQw2
Genetically predisposed individuals develop IgA antibodies to dietary gluten
These antibodies cross-react with reticulin which is a component of the anchoring fibrils that attaches the epidermal basement membrane to the superficial papillary dermis
The injury results in subepidermal blisters
dermatitis herpetiformis
In dermatitis herpetiformis, what do individuals develop IgA antibody against? These antibodies can cross-react with what protein?
dietary gluten; reticulin
Classic presentation of dermatitis herpetiformis?
blisters occurring on the elbows and knees
What would you look for on immunofluorescence staining in dermatitis herpetiformis?
granular IgA
What does dermatitis herpetiformis look like microscopically?
subepidermal blister
eos
neutrophils
Treatment for dermatitis herpetiformis?
dapsone
sulfapyridine
Inherited defect in structural proteins that cause mechanical instability to the skin
Clinical manifestations soon after birth with blister formation at sites of pressure, rubbing or trauma
4 types Simplex – suprabasalar blister Junctional – subepidermal blister Dystrophic – subepidermal blister Mixed
Epidermolysis bullosa
Autosomal dominant inheritance of defects in keratin 14 or keratin 5 resulting in defects in the basal cell layer of the epidermis
Epidermolysis bullosa - simplex type
Autosomal recessive inheritance of defects in laminin, a protein at the lamina lucida
The lamina lucida binds to both hemidesmosomes and anchoring filaments
Blisters are seen at the level of the lamina lucida
Epidermolysis bullosa - junctional type
Autosomal dominant or recessive inheritance of defects in type VII collagen (a major component of the basement membrane anchoring fibrils)
Defects causes blisters at the level of the lamina densa
This is a scarring disorder
Epidermolysis bullosa - dystrophic type
