Dermatopathology I Flashcards
Layers of Skin
Stratum corneum
Stratum granulosum
Stratum spinosulm
Stratum Basale
Macule
Circumscribed, flat lesion <5mm distinguished from surrounding skin by color
Patch
Circumscribed, flat lesion >5mm distinguished from surrounding skin by color
Papule
Elevated dome-shaped or flat-topped lesion <5mm
Nodule
Elevated dome-shaped or flat-topped lesion >5mm
Plaque
Elevated flat-topped lesion >5mm
Pustule
Discrete, pus-filled, raised lesion
Scale
Dry, horny, platelike excrescence; usually the result of imperfect cornification
Vesicle
Fluid-filled raised lesion <5mm; also called a blister
Bulla
Fluid-filled raised lesion >5mm; also called a blister
Excoriation
Traumatic lesion breaking the epidermis and causing a raw linear area (deep scratch)
Wheal
Itchy, transient, elevated lesion with variable blanching and erythema formed as the result of dermal edema
Lichenification
Thickened, rough skin; usually the result of repeated rubbing
Acanthosis
Diffuse epidermal hyperplasia
Dyskeratosis
Abnormal, premature keratinization within cells below the stratum granulosum
Hypergranulosis
Hyperplasia of the stratum granulosum
Hyperkeratosis
Thickening of the stratum corneum
Lentiginous
A linear pattern of melanocyte proliferation within the epidermal basal cell layer
Papillomatosis
Surface elevation caused by hyperplasia and enlargement of contiguous dermal papillae
Parakeratosis
Keratinization with retained nuclei in the stratum corneum
Spongiosis
Intercellular edema of the epidermis
Acute Inflammatory Dermatoses
Last from days to weeks
Characterized by lymphocytic and macrophage inflammatory infiltrate and edema
Chronic 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
Urticaria (Hives)
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
Causes of Urticaria
Immunologic mechanisms Non-immunologic mechanisms Physical stimuli Skin contact Small vessel vasculitis
Treatment of Urticaria
Avoidance of specific allergens
Oral H1 antagonists
Epinephrine
Acute Eczematous Dermatitis
One of the most common skin disorders
Can be subdivided into 5 categories
- Allergic contact dermatitis
- Atopic dermatitis
- Drug-related eczematous dermatitis
- Photoeczematous dermatitis
- Primary irritant dermatitis
Results from T-cell mediated inflammatory reactions (TYPE IV HYPERSENSITIVITY)
Causes and treatment of acute eczematous dermatitis
Causes can be broadly categorized as
INSIDE: reaction to an internal circulating antigen
OUTSIDE: reaction from external application of an antigen
TREATMENT
Removal of the offending substance
Topical steroids
Erythema Multiforme
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
Stevens Johnson Syndrome
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
Toxic Epidermal Necrolysis
Type of erythema multiforme characterized by diffuse necrosis and sloughing of cutaneous and mucosal epithelial surfaces
Clinical picture similar to that of burn patients
Treatment of Acute Erythema Multiforme
Observation Oral antihistamines Topical steroids Acyclovir Prednisone
Treatment of Chronic Erythema Multiforme
Antivirals (acyclovir)
Dapsone
Azathioprine
Cyclosporine
Psoriasis
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 is associated with what gene and what condition?
HLA-C
Arthritis
Treatment of psoriasis
Topical steroids Intralesional steroid injection UVB and tar Methotrexate Cyclosporine Soriatane
Seborrheic Dermatitis
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
Causes of Seborrheic Dermatitis
Increased sebum production
Colonization of the skin by Malassezia
Severe form seen in HIV+ patients with low CD4 counts
Treatment of Seborrheic Dermatitis
Frequent washing of the affected area with antisebhorreic soaps
Topical steroids
Anti-yeast medications
Oral antifungals
Lichen Planus
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
6 P’s of Lichen Planus
Pruritic Purple Polygonal Planar Papules Plaques
Treatment of Lichen Planus
Topical steroids Intralesional steroids Systemic steroids Azathioprine Cyclosporine Light therapy (PUVA & UVB)
Acute Inflammatory Dermatoses
Urticaria
Acute Eczematous Dermatitis
Erythema Multiforme
Chronic Inflammatory Dermatoses
Psoriasis
Seborrheic Dermatitis
Lichen Planus
Blistering Disorders
Pemphigus
Bullous Pemphigoid
Dermatitis Herpetiformis
Epidermolysis Bullosa
Pemphigus
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
In Pemphigus, _______ to ________ disrupt intercellular adhesions of desmosomes
IgG autoantibodies, Desmoglein 1 and 3
Pemphigus Variants
Pemphigus vulgaris Pemphigus vegetans Pemphigus foliaceus Pemphigus erythematosus Paraneoplastic pemphigus
Pemphigus treatment
Immunosuppressive agents to decrease the titers of the pathogenic antibodies
Bullous Pemphigoid
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
In bullous pemphigoid, the protein _______ are part of the hemidesmosomes that link _______ to ______
BPAGs
keratinocytes
basement membrane
Treatment of Bullous Pemphigoid
Topical steroids
Systemic steroids
Methotrexate
Azathioprine
Dermatitis Herpetiformis
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
Which genes are strongly associated with dermatitis herpetiformis
HLA-B8
HLA-DR3
HLA-DQw2
With dermatitis herpetiformis, genetically predisposed individuals develop ______ to _____
IgA antibodies to dietary gluten
The IgA antibodies created in Dermatitis herpetiformis cross react with which protein and what is the role of this protein
Reticulin, a component of the anchoring fibrils that attaches to the epidermal basement membrae to the superficial papillary dermis
Treamtment of Dermatitis Herpetiformis
Dapsone
Sulfapyridine
Epidermolysis Bullosa
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
- Junctional
- Dystrophic
- Mixed
Epidermolysis Bullosa Simplex Type
Autosomal dominant inheritance of defects in keratin 14 or keratin 5 resulting in defects in the basal cell layer of the epidermis
Epidermolysis Bullosa Junctional 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 Dystrophic 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
What is the defect in epidermolysis bullosa simplex type
Keratin 14 or 5
What is the defect in epidermolysis bullosa junctional type
laminin
What is the defect in epidermolysis bullosa dystrophic type
type VII collagen
