Dermatology Flashcards
basal layer/stratum basale
bottom-most layer of the epidermis, attached to the basement membrane; houses stem cells that maintain the epidermis; when a stem cell divides, it creates both a daughter stem cell and a transient amplifying cell
spinous layer/stratum spinosum
second-deepest layer of the epidermis, located between the basal layer and the granular layer; contains the majority of the skin’s keratinocytes (i.e., thickest layer), which are held together by desmosomes, gap junctions, adherens junctions, and tight junctions
granular layer/stratum granulosum
second-most-superficial layer of the epidermis, located between the spinous layer and the cornified layer; keratinocytes in this layer are flattened, begin to lose their nuclei, and contain keratinohyaline granules and lamellar granules
transluscent layer/stratum lucidum
additional layer of the epidermis located between the cornfield layer and the granular layer; present only on the palms and soles
cornified layer/stratum corneum
most-superficial layer of the epidermis; contains corneocytes held together by a cornified envelope, made up of proteins and lipids released by keratohyalin and lamellar granules of the granular layer; thickness of this layer varies depending on the body area
keratinocyte
keratinized cells of the epidermis of the skin; contain keratin, an intermediate filament, made up of heterodimers of alpha-helical type I (acidic) and type II (basic) keratin monomers; derived from stem cells in the basal layer of the epidermis, undergo cornification as they differentiate and mature (takes appx. 28 days)
corneocyte
anucleate keratinocytes held together by the cornified envelope found in the cornified layer of the epidermis
desmosome
adhesive protein that connects to keratin intermediate filaments intracellularly and to neighboring cells extracellularly; holds neighboring cells together in the epidermis
keratohyalin granules
granules present in keratinocytes of the granular layer of the epidermis; contain proteins important for formation of the cornified envelope, including profilaggrin
lamellar granules
granules present in keratinocytes of the granular layer of the epidermis; contain ceramides and cholesterol that contribute to the lipid barrier of the cornified layer and hydrolytic enzymes that promote desquamation of the cornified layer
filaggrin
protein found in keratohyalin granules of the keratinocytes in the granular layer of the epidermis; contributes to the cornified envelope of the cornified layer
ceramide
lipid found in lamellar granules of the keratinocytes in the granular layer of the epidermis; contributes to the cornified envelope of the cornified layer
desmoglein
protein that makes up desmosomes; isoforms 1 and 3 targeted by autoantibodies in pemphigus vulgaris
papillary dermis
superficial layer of the dermis; interdigitates with the rate ridges/pegs of the epidermis, is more cellular than the reticular dermis, and has fine/loosely-woven collagen that runs perpendicular to the dermal-epidermal border
reticular dermis
deep layer of the dermis; is less cellular than the papillary dermis and has coarse, thick, tightly-packed collagen that runs parallel to the dermal-epidermal border
extracellular matrix
acellular scaffold that provides structure to a tissue and regulates cell functions such as adhesion, migration, division, and apoptosis; made up of collagen, elastic fibers, and extrafibrillar matrix; main component of the dermis of the skin
collagen
ECM protein produced by fibroblasts; main subunit is a trimer of alpha-chains containing 3-nucleotide repeats of glycine, proline, and hydroxyproline, which is exported to the extracellular space, cleaved, and assembled into fibers; 28 types exist, 12 are present in skin, type I is most abundant in skin, type III is second-most abundant; type III is more important in embryogenesis and wound healing
elastic fibers
ECM protein composed of microfibrils made of fibrillin and amorphous elastin; provides skin with elasticity
ground substance
AKA extrafibrillar matrix; non-collagen, non-elastin component of dermis composed of water, electrolytes, plasma proteins, and proteoglycans
fibroblast
predominant cell type in the dermis of the skin; derived embryonically from the mesoderm; produces and secretes components of the ECM
Pacinian corpuscle
specialized sensory receptor located in the deep dermis and subcutaneous tissue of weight-bearing surfaces, lips, nipples, penis, and clitoris; detect pressure and vibration
Meissner’s corpuscle
specialized sensory receptor located just below the epidermis in the papillary dermis of the palms and soles; detect light touch
fibrillin
protein component of elastic fibers; mutated in Marfan syndrome
subcutaneous fat
layer of tissue below the dermis of the skin made up of adipocytes; derived embryonically from the mesoderm; stores energy and provides insulation and shock absorption
adipocyte
fat-storing cell located in the subcutaneous fat layer; synthesizes and stores lipids in cytoplasm with nucleus displaced to one edge
basement membrane zone
protein layer that provides dermo-epidermal adhesion; regulates cell differentiation, motility, and extracellular signaling
hemidesmosome
protein structure of the BMZ located on inner surface of basal keratinocytes that connects them to the ECM; includes hemidesmosomes, lamina lucida, lamina dens, and sublamina dens
sunscreen
topical cream that prevents UV radiation from damaging the skin; may contain physical blockers and/or chemical blockers
physical blocker
a component of sunscreen that reflects UV radiation; examples include zinc oxide and titanium dioxide
chemical blocker
a component of sunscreen that absorbs UV radiation and converts it to heat; examples include para-aminobenzoic acid (PABA), avobenzone, oxybenzone, cinnamates, and salicylates
sun protection factor
measure of protection against UVB exposure; MED protected/MED unprotected (i.e., factor by which you can multiply your time in the sun without getting sunburned)
lamina lucida
layer of the BMZ found just beneath the hemidesmosomes; may be an artifact of tissue preparation
lamina densa
layer of the BMZ composed of type IV collagen and laminins
sublamina densa
layer of the BMZ composed of type VII collagen; maintains epidermal-dermal cohesion by binding both type I and type IV collagens
BP230 (BP antigen 1)
cytoplasmic protein in the plakin family; contributes to organization of the cytoskeletal architecture; may be targeted by autoantibodies in bullous pemphigoid
BP180 (BP antigen 2)
AKA type XVII collagen; transmembrane protein that connects basal keratinocytes and cytoskeleton to dermal collagen VII/laminin 332; may be targeted by autoantibodies in bullous pemphigoid
laminin 332
primary BMZ laminin; heterotrimer; binds transmembrane domain of hemidesmosome integrin and to type VII collagen (bridges the BMZ)
direct immunofluorescence
diagnostic procedure using a patient perilesional skin sample and fluorescein-conjugated antibodies to detect immunoglobulin or complement in situ
indirect immunofluorescence
diagnostic procedure using normal human skin (sometimes split at the lamina lucida by salt), patient serum, and fluorescein-conjugated antibodies to detect circulating antibodies in the patient serum
ELISA
enzyme-linked immunosorbent assay; diagnostic procedure used to detect circulating autoantibodies in patient serum
hemostasis
first step in cutaneous wound healing; reflexive vasoconstriction occurs in response to damage signals from cells and vessels; mediators include endothelin (from endothelium), catecholamines, and prostaglandins (from injured cells); coagulation cascade is initiated by bradykinin, serotonin, and thromboxane A2
inflammation
second step in cutaneous wound healing; involves vasodilation and increased vascular permability mediated by kinins, histamine, prostaglandins, and leukotrienes, followed by leukocyte recruitment
proliferation
third step in cutaneous wound healing; involves re-epithelialization of the wound, which begins with epidermal thickening along wound edges; also mediated by fibroblasts (last cell population to enter wound - attracted by PDGF, IGF-1, TGF-beta from platelets), smooth muscle cells, and endothelial cells, which synthesize collagen (allows basal cell migration) and promote angiogenesis
maturation
final step in cutaneous wound healing; involves clearance of inflammatory cells from scar tissue, fibroblast apoptosis, blood vessel maturation, and collagen remodeling/maturation
Langerhans cell
antigen-presenting cell found in the skin; primarily found in the spinous layer, but present throughout the dermis and epidermis; mesoderm/bone marrow-derived
macule
flat, non-palpable skin lesion
patch
flat, non-palpable skin lesion > 1 cm in diameter
papule
elevated or depressed, palpable skin lesion
plaque
elevated or depressed, palpable skin lesion with a broad and flat surface > 1 cm in diameter
nodule
palpable skin lesion with a rounded surface > 1 cm in diameter; characteristic of inflammatory acne, indicative of a mixed-inflammatory response (lymphocytes, giant cells, and neutrophils)
vesicle
fluid-filled blister
bulla
fluid-filled blister > 1 cm in diameter
pustule
pus-filled blister; characteristic lesion of inflammatory ache, indicative of a neutrophil-dominant reaction
wheal
edematous papillose and plaques that are characteristic of hives
erosion
open area of the skin with partial or full loss of epidermis
ulcer
open area of the skin with loss of part of the dermis
fissure
linear ulcer
telangiectasia
dilated blood vessels visible on the surface of the skin
petechiae
pinpoint areas of hemorrhage on the skin
purpura
area of hemorrhage on the skin; can be flat or elevated
pemphigus vulgaris
autoimmune blistering disease caused by autoantibodies against desmosomal proteins (desmoglein 1 and 3); most common in the elderly; symptoms include flaccid, intraepidermal blisters that progress into erosions on mucosal and cutaneous sites; can be fatal; tx includes immunosuppressive rx (i.e. prednisone, azathioprine, mycophenolate mofetil, rituximab)
ichthyosis vulgaris
autosomal dominant genetic disease caused by mutations in the profilaggrin gene/defective cornified envelope; symptoms include large scaly areas on the body (particularly on the shins and other extremities), dry skin, hyperlinear palms, and predisposition to atopic dermatitis, allergic rhinitis, food allergies, and asthma
Marfan syndrome
autosomal dominant genetic disease caused by mutations in fibrillin; symptoms include tall and thin body type, long limbs/fingers, scoliosis, flexible joints, striae, nearsightedness, lens dislocation, aortic dilation/aneurysm, and mitral valve prolapse
Ehlers-Danlos syndrome
group of genetic diseases caused by mutations in the structure, production, processing, or assembly of collagen; symptoms include fragile/super-elastic skin prone to scarring, extremely flexible joints, scoliosis, and ruptured blood vessels/intestines/uterus
morphea
autoimmune disease; affects both children and adults, more common in females; symptoms include erythematous and indurated plaques that slowly expand and may cause fibrotic/atrophic scars; may also include joint and neurologic complications
systemic sclerosis
autoimmune disease; most common in young to middle-aged women; subtypes include limited systemic sclerosis (CREST syndrome) and diffuse systemic sclerosis; symptoms of limited systemic sclerosis include Calcinosis cutis, Raynaud phenomenon, Esophageal dysmotility, Sclerodactyly, and Telangiectasia of the face; symptoms of diffuse systemic sclerosis include widespread sclerosis of the skin, pulmonary fibrosis, renal failure, GI disease, and cardiac disease
erythema nodosum
acquired disorder with multiple causes (i.e. idiopathic, infection, etc.); triggers include upper respiratory strep infection, medications (oral contraceptives), sarcoidosis, IBD, and malignancy; form of panniculitis (inflammation of subcutaneous fat); symptoms include tender, red nodules on the shins that resolve within a few days or weeks
bullous pemphigoid
autoimmune bullous disease caused by autoantibodies against BP230 and BP180; most common in the elderly; symptoms include highly pruritic urticaria followed by tense, stable, subepidermal blisters with serous or hemorrhagic content; DIF, linear IgG/C3 deposits along BMZ; IIF, linear staining on epidermal side of split skin; Tx with steroids
mucous membrane pemphigoid
autoimmune disease caused by autoantibodies against BP180, BP230, integrin beta4, or laminin 332; most common in the elderly; symptoms include recurrent blistering of mucous membranes and skin, scars, strictures, synechiae, blindness; association with malignancy also seen in those with anti-laminin 332; DIF, linear IgG/C3 deposits along BMZ; IIF, linear staining on epidermal, dermal + epidermal, or dermal side of split skin
epidermolysis bullosa acquisita
autoimmune disease caused by autoantibodies against type VII collagen; symptoms include blistering and erosion elicited by any trauma, particularly on mechanically-stressed areas (hands, feet, elbows, knees), atrophy, milia, scars, pigmentation disorders, fibrosis of hands and feet, nail dystrophy, and hemorrhagic erosions of oral mucosa; DIF, linear IgG/C3 deposits along BMZ; IIF, linear staining on dermal side of split skin (no ELISA test)
epidermolysis bullosa
genetic disease caused by mutations in BMZ proteins (keratins 5 and 14, pectin, collagen VII and XVII, alph6beta4 integrin, laminin 332); symptoms include blistering and erosion elicited by any trauma, as well as others depending on disease subtype
sebaceous glands
glands that produce sebum (triglycerides, fatty acids, squalene, wax, sterols) and are associated with hair follicles (except on vermilion lips, urogenital mucosa, areolae, and eyelids); present in highest density on face and scalp, but are present everywhere on body except palms and soles; sebum secretion occurs continuously and via holocrine secretion under the influence of maternal hormones or androgens
vellus hair
fine, short hairs found on most body surfaces; during puberty, some changes to terminal hair under the influence of androgens (beard, axillae, pubic)
terminal hair
coarse, dark hair that grows longer than other types of hair; before puberty, found on the scalp, eyelashes, and eyebrows; after puberty, also appears on beard, axillae, and pubic areas
anagen
hair growth phase; on the scalp, lasts 2-6 years; at any given time, appx. 85% of scalp hairs are in anagen
catagen
hair regression phase; on scalp, lasts 2-3 weeks; at any given time,
telogen
hair resting phase; on scalp, lasts appx. 3 months; at any given time, appx. 10-15% of scalp hairs are in telogen
eccrine glands
one of the two types of sweat glands; present on all cutaneous surfaces, but found in greatest density on palms and soles; innervated by postganglionic sympathetic fibers controlled by the hypothalamic sweat center using acetylcholine as the principal neurotransmitter; apical portion (acrosyringium) is intraepidermal and drains directly onto cutaneous surface; secrete via merocrine mechanics
apocrine glands
one of two types of sweat glands; present on the axillae, anogenital region, periiumbilical region, areolae, nipples, and vermilion border of the lips; secrete oily, viscous fluid that is degraded by cutaneous bacteria into odiferous substances; secretion is controlled by catecholamines and cholinergic agonists (poorly understood); duct opens into the upper portion of the hair follicle; secrete via apocrine mechanics
comedone
plugged hair follicles due to increased sebum production and increased production/decreased shedding of corneocytes; characteristic lesions of non-inflammatory acne; may be closed (whiteheads) or open (blackheads)
inflammatory papules
one of the characteristic lesions of inflammatory acne; indicates a mixed-inflammatory response (lymphocytes, giant cells, neutrophils)
acne cysts
one of the characteristic lesions of inflammatory acne; indicates a mixed-inflammatory response (lymphocytes, giant cells, neutrophils)
melanocyte
dendritic cells derived from the neural crest that reside in the stratum basale of the epidermis and produce melanin; density in normal skin is generally one melanocyte to 10 keratinocytes, but may vary with location and degree of sun damage
melanin
pigment produced by melanocytes
melanosomes
melanin-containing vesicles synthesized by melanocytes, then transferred to neighboring keratinocytes