Skin-nontumor / Clinical dermatology
General
Common pathologic terms

Author: Cecilia Rosales, M.D, Baylor College (see Authors page)

Revised: 19 May 2016, last major update August 2010

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Common pathologic terms

Table of Contents
Definition / General
Definition / General
  • Acantholysis: loss of intercellular connections (desmosomes) between keratinocytes; occurs in pemphigus vulgaris and related disorders; causes change in cell shape from polygonal to round
  • Acanthosis: thickening of epidermis (squamous layer); rete ridges usually extend deeper into dermis
  • Atrophy: thinning of epidermis, associated with age or disease
  • Basophilic degeneration: age and sunlight related changes of collagen and elastic fibers
  • Blister: vesicle or bullae
  • Bullae: fluid filled area > 5 mm; either intraepidermal or subepidermal; intraepidermal bullae are due to spongiosis or acantholysis; subepidermal bullae are due to extensive papillary dermal edema
  • Calcinosis: deposit of calcium
  • Colloid bodies: also called Civatte bodies; apoptotic keratinocytes, are oval/round, immediately above or below epidermal basement membrane
  • Comedo: hair follicle infundibulum is dilated and plugged with keratin and lipids
  • Cyst: encapsulated cavity or sac lined by true epithelium
  • Dyskeratosis: abnormal, premature keratinization of keratinocytes below granular cell layer; often have brightly eosinophilic cytoplasm
  • Epidermolysis: alteration of granular layer with perinuclear clear spaces, swollen and irregular keratohyalin granules, increased thickness of granular layer; different from acantholysis
  • Epidermotropism: atypical lymphocytes present in epidermis (seen in cutaneous T cell lymphoma)
  • Erosion: discontinuity of skin causing partial loss of epidermis (compare to ulceration)
  • Excoriation: deep linear scratch, often self-induced
  • Exocytosis: normal appearing lymphocytes in epidermis (spongiotic dermatitis)
  • Horn: conical mass of cornifed cells
  • Hydropic (liquefactive) degeneration: basal cells become vacuolated, separated and disorganized
  • Hyperkeratosis: thickened cornified layer, often with prominent granular layer; keratin may be abnormal; either orthokeratotic (hyperkeratosis is exaggeration of normal pattern of keratinization with no nuclei in cornified layer) or parakeratotic (hyperkeratosis has retained nuclei in cornified layer)
  • Lentiginous: linear pattern of melanocytic proliferation within epidermal basal cell layer
  • Leukocytoclasis: karyorrhexis and destruction of neutrophils; occurs with neutrophilic vasculitis (also called leukocytoclastic vasculitis)
  • Lichenification: thick, rough skin with prominent skin markings usually due to repeated rubbing
  • Lichenoid interface change: destruction of basal keratinocytes, causing remodeling of basement membrane zone; also bandlike lymphocytic infiltrate
  • Macule: circumscribed flat colored area of any size
  • Nodule: solid, deeply extending lesion > 5 mm
  • Oncholysis: loss of integrity of nail substance
  • Papillomatosis: outward overgrowth of epidermis with elongation of dermal papillae
  • Papule: elevated and solid area, 5 mm or less
  • Parakeratosis: cells of cornified layer retain their nuclei, often less prominent or absent granular layer; normal for mucous membranes
  • Patch: flat discoloration > 5 mm
  • Papule: solid elevated lesion < 5 mm
  • Plaque: elevated flat topped area, usually > 5 mm
  • Poikiloderma: combination of atrophy, telangiectasia and pigmentary changes
  • Purpura: extravasation of red blood cells into the skin or mucous membranes
  • Pustule: intraepidermal or subepidermal vesicle or bullae filled with neutrophils
  • Scale: dry, horny, platelike excrescence usually due to imperfect cornification
  • Scale crust: parakeratotic debris, degenerating inflammatory cells and tissue exudate on surface of epidermis
  • Sinus: tract connecting cavities to each other or to the surface
  • Spongiosis: intraepidermal edema, causing splaying apart of keratinocytes in stratum spinosum (resembling a sponge), vesicles due to shearing of desmosomes
  • Ulceration: discontinuity of skin causing complete loss of epidermis and possible loss of dermis
  • Vesicle: fluid filed area, 5 mm or less
  • Wheal: itchy, transient, elevated area with variable blanching and erythema, due to dermal edema