Definitions Flashcards
Loss of cohesion between individual keratinocytes with breakdown of desmosomes leading to round cells with a central nucleus that is rimmed by condensed eosinophilic cytoplasm
Acantholysis
Increased thickness of the stratum spinosum
Acanthosis
Individual programmed cell death leading to eosinophilic, shrunken cells
Apoptosis
Intracellular oedema leading to swollen, eosinophilic cytoplasm, enlarged or condensed nuclei, loss of cohesion and vesicle formation
Ballooning degeneration
Premature or abnormal keratinisation of individual keratinocytes leading to eosinophilic, shrunken cells with condensed, dark staining nuclei
Dyskeratosis
Deposition of calcium salts as basophilic, amorphous, granular material along collagen fibrils
Dystrophic mineralisation
Giant clumps of melanin found within melanocytes or hair shafts
Macromelanosomes
Migration of inflammatory cells through the intercellular spaces of the epidermis
Exocytosis
Dermal papillae devoid of attached epithelial cells that project into a vesicle or bulla
Festoons
Deposition of amorphous eosinophilic material resembling fibrin in the walls of blood vessels
Fibrinoid degeneration/necrosis
Formation and development of fibrous reactive tissue
Fibroplasia
Inflammation of the hair follicle that has resulted in destruction of the follicular epithelium and release of luminal contents into the dermis
Furunculosis
Relatively normal collagen that separates the epidermis from an underlying dermal alteration
Grenz zone
Tumour-like malformation of an abnormal mixture of normal tissue elements or an abnormal single element (normal to location)
Hamartoma
Inflammation of epitrichial (apocrine) sweat glands
Hidradenitis
Focal, circular, concentric layers of squamous cells showing gradual keratinisation toward the centre
Keratin pearls
Increased thickness of the stratrum corneum with no nuclei
Orthokeratotic hyperkeratosis
Increased thickness of the stratum corneum with nucleated cells
Parakeratotic hyperkeratosis
Increase in number of epidermal cells with even rete ridges
Regular or Psoriasiform hyperplasia
Extreme, irregular epidermal hyperplasia with increased mitosis and branched or fused rete pegs
Pseudocarcinomatous hyperplasia
Intracellular oedema restricted to the basal layer of the epidermis and outer root sheath with clear vacuoles within the keratinocytes
Hydropic degeneration
Accumulation of dermal ground substance - granular, basophilic material that separates or thins collagen fibres
Mucinosis
Small, desiccated accumulations of neutrophils in stratum corneum
Munro’s microabscess
Loss of keratinocyte intercellular bridges, rounding of cells, normal-sized or swollen eosinophilic cytoplasm, pyknotic nucleus
Necrosis
Projection of dermal papillae and epidermis above the surface of the skin
Papillomatosis
Small, focal accumulation of abnormal lymphoid cells in the epidermis/follicular epithelium
Pautrier’s microabscess
Free melanin granules within the subepidermal dermis and dermal macrophages (melanophages)
Pigmentary incontinence
Severe intracellular oedema of epidermal cells, cells burst and result in multilocular intraepidermal vesicles whose septa are formed by resistant cell walls
Reticular degeneration
Individual necrotic keratinocytes in the epidermis surrounded by lymphoid cells
Satellitosis
End point of fibrosis – increased numbers of collagen fibres, thick hyalinised appearance, reduced numbers of fibroblasts
Sclerosis
Epidermal widening of intercellular spaces with accentuation of intercellular bridges that may lead to intraepidermal/subepidermal vesicles
Spongiosis
Whorl-like patterns of squamous cells with no atypia, dyskeratosis or central keratinisation
Squamous eddies
Dermal papilla covered by 1-2 layers of epidermal cells that projects into the base of a vesicle/bulla
Villus
What does coagulation necrosis look like?
Typical microscopic changes in coagulative necrosis become prominent in 4-12 hours, there is preservation of basic outline of injured cells along with denaturation of cellular proteins. There is increased eosinophilia due to denaturation of proteins, loss of normal basophilia imparted by RNA degeneration. Secondly, eosin stain has more affinity for denatured proteins.
