Lecture 3 11/27/25 Flashcards
(50 cards)
What are the responses of the epidermis to injury?
-changes in growth or differentiation
-changes in fluid balance or cell adhesion
-inflammation
-alterations in epidermal pigment
What are the potential alterations in epidermal growth/differentiation?
-hyperkeratosis
-epidermal hyperplasia
-dysplasia
-atrophy
-dyskeratosis/apoptosis/necrosis
What are the characteristics of hyperkeratosis?
-increased thickness of stratum corneum/keratin layer
-can be a non-specific reaction to chronic stimuli
What are the conditions that cause orthokeratotic (lacking nuclei) hyperkeratosis?
-seborrhea
-ichthyosis
-vitamin A deficiency
What are the conditions that cause parakeratotic (retaining nuclei) hyperkeratosis?
-zinc-responsive dermatosis
-superficial necrolytic dermatitis
What are the characteristics of epidermal hyperplasia?
-increased thickness of epidermis due to increased number of cells
-typically in stratum spinosum; termed acanthosis
-non-specific response to chronic stimuli
What are the characteristics of rete pegs?
-down-growths of epidermis into dermis
-normal in areas of high friction
-seen in areas with chronic irritation (abnormal)
What are the characteristics of epidermal dysplasia?
-abnormal development of the epidermis
-disorganization of any of the epidermal layers
-typically occurs in basal cells
-often a pre-neoplastic lesion
What is epidermal atrophy?
decrease in the number and size of cells within the epidermis
What are the possible causes of epidermal atrophy?
-hyperadrenocorticism
-partial ischemia
-severe malnutrition
What are the characteristics of dyskeratosis, apoptosis, and necrosis?
-distinct pathogenesis that are histologically identical
-cells become shrunken and hypereosinophilic
Which diseases have dyskeratosis/apoptosis/necrosis confined to the basal layer?
-discoid lupus
-mucocutaneous pyoderma
Which disease has dyskeratosis/apoptosis/necrosis in multifocal spots throughout all layers?
erythema multiforme
Which diseases have dyskeratosis/apoptosis/necrosis in a diffuse pattern/full thickness?
-toxic epidermal necrolysis
-thermal injury
What are the potential consequences of alterations in the epidermal adhesion molecules?
-edema/fluid buildup
-acantholysis/loss of cell adhesion
What are the mechanisms of vesicle formation?
-widening of intercellular spaces due to worsening edema; causes spongiosis
-loss of cells due to worsening edema; causes ballooning degeneration/intra-cellular edema
-loss of intercellular junctions resulting in separation of cells; causes acantholysis
Which disease processes can lead to acantholytic cells?
-immune-mediated processes
-neutrophilic enzyme destruction
How do acantholytic cells differ from apoptotic cells on cytology?
-acantholytic cells are typically disassociated from other cells
-apoptotic cells are not disassociated from other cells
How does vesicle location and appearance within the epidermis differ with different pemphigus types?
-pemphigus folicaceous: vesicle develops “between” epidermis and stratum corneum and contains acantholytic cells
-pemphigus vulgaris: vesicle develops “between” epidermis and dermis and contains acantholytic cells
-bullous pemphigoid/thermal burns: vesicle develops “between” epidermis and dermis with no acantholytic cells
What is exocytosis?
inflammatory cells “walking” through the epidermis
What is a pustule?
accumulation of cells in the epidermis that have moved via exocytosis
Which cells accumulate in a pustule and when?
-neutrophils: bacterial infection, pemphigus
-eosinophils: ectoparasites, pemphigus
When do crusts form?
as pustules dry up and are pushed off by the hyperplastic epidermis
What are the potential alterations in epidermal pigmentation?
-hyperpigmentation
-pigmentary incontinence
