Dermatology
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107 terms
Terms | Definitions |
|---|---|
 What's special about the skin of your palm and sole? | Acral skin thick stratum corneum |
| Epidermis (epithelium type, cell types) | Keratinizing stratified squamous epithelium Cell types: Keratinocytes, Melanocytes, Langerhans cells, Merkel cells |
| Keratinocytes (% of epidermis, layers) | 80% epidermis Basal layer (stratum basale): single proliferative layer, basophilic, columnar/cuboidal Spinous layer (stratum spinosum, stratum malpighii): polygonal, eosinophilic, desmosomal spines Granular layer (stratum granulosum): basophilic, keratohyaline granules Cornified layer (stratum corneum): no nuc, flatten plates of keratin |
| Stratum malpighii | Stratum spinosum Spinous layer of epidermis made by keratinocytes |
| Time for skin turn over fully and to botton of stratum corneum | Fully (from stratum basale to top of stratum corneum): 30 days From stratum basale to bottom of stratum corneum: 15 days Just through stratum corneum: 15 days |
| Squamous cell carcinoma is cancer of what cell? | Keratinocytes |
| Basal cell carcinoma is cancer of what cell? | Keratinocytes in basal layer (Stratum basale) |
| Melanocytes (% of epidermis, origin, location, appearance, fxn) | 10-15% epidermis (1:4-1:10::melanocyte:basal cell) Origin: neural crest Location: basal layer Appearance: dendritic w stellate projections Fxn: make melanin (in melanosomes) to protect from UV |
| Melanin distribution | Melanocytes produce --> distribute to keratinocytes, mostly basal layer Collect up top to protect nuc from sun |
| What makes skin color dark vs light? | Not # of melanocytes Dark skin: melanosomes more evenly dispersed in keratinocytes, more tyrosinase activity, more melanin content |
| Vitiligo | Autoimmune against melanocytes |
| Melanoma is cancer of what cell? | Melanocytes |
| Birbeck granules | In Langerhans cells Looks like tennis racket Fxn unk |
| Langerhans cells (%, origin, location, appearance | 3-5% epidermis APCs (bone marrow derived, delayed hypersensitivity) Location: Suprabasilar epidermis Appearance: dendritic w stellate projections, have Birbeck granules (can only see w electron microscope) |
| Cancer of Langerhans cells | Langerhans cells histiocytosis AKA Histiocytosis X |
| Merkel cell (%, location, fxn) | <1% epidermis Location: epidermis & dermis Fxn: aggregate to form tactile corpuscles (slow-adapting touch receptors) |
| Basement membrane zone | Jxn between dermis & epidermis Lamina lucida: basal layer of epidermis attach to lamina densa via hemidesmosomes Lamina densa/Basal lamina: type IV collagen Sublamina densa |
| Epidermolysis bullosa | Defective anchoring fibrils that attach basal lamina to sublamina densa Epidermis slough off of dermis |
| Pilosebaceous unit | 1. Hair follicle 2. Sebaceous gland 3. Arrector pili muscle |
| Hair follicle | Inferior: base of follicle to arrector pili muscle insertion Isthmus: arrector pili muscle to sebaceous gland Infundibulum: sebaceous gland to skin surface |
| Hair anatomy from in to out | Hair shaft Cuticle Inner root sheath Outer root sheath (glycogenated) |
| Hair cycle | Anagen: growth, 3-4 years, 90% Catagen - involution, 3 days, 1% Telogen - rest, 3 months, 10% |
| Alopecia areata vs Alopecia universalis | Autoimmune against hair shaft (baldness) Areata: bald spots Universalis: no hair at all |
| Where are sabaceous glands found? | Everywhere except palms and soles Especially abundant in face, scalp, chest, back |
| How do sebaceous glands secrete? | Holocrine secretion |
| At what age do sebaceous glands become functional? | Puberty |
| Acne vulgaris | Blocked sebaceous glands --> oil bursts backwards |
| Where are apocrine glands found? | Mostly axillae & groin Eyelids (moll's glands) External auditory canal (ceruminous glands) |
| Moll's glands | Modified apocrine glands in eyelids |
| Cerminous glands | Modified apocrine glands in ears |
| Apocrine gland anatomy | Coiled gland --> Straight duct --> Exit into hair follicle or skin surface |
| Secretory components of apocrine gland | Inner secretory layer: cuboidal/columnar epithelial layer --> apocrine decapitation secretion Outer squeezing layer: myoepithelium |
| Hidradenitis Suppurativa (hi-draw-den-itis sup-pora- tiva) | Blocked apocrine glands --> sweat bursts backwards |
| Apocrine vs Eccrine gland stimulation | Apocrine: Adrenergic (fear/excitement) Eccrine: Cholinergic (thermal, mental, gustatory) |
| Where are eccrine glands found? | Everywhere except mucous membranes Most dense on palms, soles, axillae, forehead |
| Eccrine gland anatomy | Coiled gland (secretory) --> coiled duct --> straight duct (toward skin surface) --> spiraled duct in epidermis/acrosyringium |
| Acrosyringium | Spiraled duct in epidermis |
| Secretory components of eccrine gland | Inner secretory layer: 2 cell types (larger glycogen-rich pale cells & smaller darker cells) Outer squeezing layer: myoepithelium Located in deep dermis/superficial fat |
| Hyperhidrosis | Too much eccrine sweat |
| Eccrine poroma | Benign tumor of eccrine gland |
| Dermis layers | Papillary dermis: superficial, type III collagen, thinner Reticular dermis: deep, type I collagen, thicker |
| Dermis composition | Connective tissue: fibroblasts, mast cells, dermal dendrocytes (APCs), collagen, elastic tissue, ground substance Epidermal appendages Blood vessels Nerves |
| Collagen in skin (type & location) | Collagen I: reticular dermis, most abundant, tightly bundled Collagen III: papillary dermis, fine/loosely arranged Collagen IV: lamina densa of basement membrane Collagen VII: anchoring fibrils of basement membrane between lamina densa & sublamina densa |
| Ehlers Danlos Syndrome | Collagen defect Hyper-extensible skin, hyper-mobile joints |
| Desmosine & Isodesmosine | Amino acids unique to elastin protein |
| Elastic tissue (synthesizer, fxn, composition | Synthesizer: fibroblasts Fxn: recoil, elastic properties Composition: elastin (protein, desmosine & isodesmosine) & microfibrillary matrix |
| Is elastic tissue easier to see in tissue samples of older or younger pts? | Easier in older bc elastin damaged from sun and are more visible |
| Solar elastosis | Damaged elastic tissue from sun exposure Clumps of elastotic material |
| Ground substance/ECM (synthesizer, fxn, composition) | Synthesizer: fibroblasts Fxn: skin hydration, redistributes pressure forces, some elasticity Composition: fibronectin & glycosaminoglycans (hyaluronic acid mostly, chondroitin sulfate, dermatan sulfate) |
| Pretibial myxedema | Too much ground substance (too much mucin/hyaluronic acid) |
| Fibroblast (synthesis, other fxn) | Synthesize: Connective tissue components (collagen, elastic tissue, ground substance) Other fxn: contractile cell during wound healing |
| Keloid | Over-working fibroblasts --> huge hypertrophic scars |
| Type of nerve supply in skin | 1. Free nerve ending: temp, pain, itch 2. Meissner's corpuscle: fine touch 3. Merkel cell complex: slow adapting touch 4. Pacinian corpuscle: deep pressure, vibration |
| Sensation of free nerve endings | Temp, pain, pruritis |
| Sensation of Meissner's corpuscle | Fine touch |
| Sensation of Merkel cell complex | Slow adapting touch |
| Sensation of Pacinian corpuscle | Deep pressure, vibration |
| What sensory receptors are in the papillary dermis? | Free nerve endings Meissner's corpuscles |
| Pacinian corpuscle location | Deep dermis |
| Dermal vascular supply (plexus, location, fxn) | Superficial vascular plexus (AKA subpapillary plexus): papillary-reticular dermis jxn, supply dermal papillae (nutrients to epidermis via difusion) Deep vascular plexus: dermal-subcutaneous interface Both communicate, supply epidermal adnexal structures |
| Hemangioma vs Angiosarcoma | Hemangioma: Benign proliferation of vessel supply Angiosarcoma: Malignant blood vessels |
| Lesion types | Macule Papule Plaque Nodule Vesicle Bulla Pustule |
| Macule (mac-cue -ole) | Flat spot that's a different color than the rest of the skin (any size/shape) Cause: hyper/hypopigmentation, vascular abnormality, dil capillaries, extravasated RBCs (bruise) |
| Papule (pap-pue-ole) | Small (<1cm) circumscribed solid elevation |
| Plaque | Broad and flatted elevation (SA>>height) >1cm |
| Nodule | Large papule (>1cm) Substantial length, width, depth |
| Vesicle | Small (<0.5cm) fluid-filled lesion Fluid: serum, lymph, or blood Cause: skin separation at any level |
| Bulla (bull-la) | Large (>0.5cm) fluid-filled lesion Fluid: serum, lymph, or blood Cause: skin separation at any level |
| Pustule | Purulent-filled lesion that's circumscribed and elevated Contains PMNs (+/- bacteria) |
| Lesion evolution (secondary changes) | Erosion Crust |
| Erosion (description, cause) | Circumscribed, moist, depressed lesion Cause: epidermis lost bc vesicle/bulla ruptured, or epidermal necrosis |
| Crust | Dried serum, blood, purulent exudate Can be thin/delicate or thick/adherent |
| Lesion shape vs arrangement | Shape: morphology of individual lesion Arrangement: how lesion arrange together Linear (usually exogenous cause) Annular (ring) Targetoid Arciform (partial ring) Serpiginous (snake) Grouped (herpetiform, dermatomal/zosteriform) Reticular (net-like) |
| Arciform | Partial ring shape |
| Serpiginous | Snake-like shape |
| Herpetiform grouped lesions | Clusters of vesicles Characteristics of HSV |
| Zosteriform grouped lesions | AKA dermatomal grouped lesions Lesions following dermatome |
| What does KOH examination test for? | Fungal infections (find fungus by killing all non-fungal cells with KOH) |
| What does Tzanck ("zank") preparation test for? | Herpetic infection |
| What does patch testing look for? | Allergic rxn |
| Skin biopsies | 1. Punch biopsy 2. Shave biopsy 3. Excision biopsy |
| Impetigo (cause, population, tx) | Contagious superficial skin infection Cause: Gram +ve (Staph aureus or Strep pyogenes) Population: most common bacterial infection in kids Tx: clean/remove crust, mupirocin 2% ointment, oral antibiotic |
| Non-bullous vs Bullous impetigo | Non-bullous: 70% of cases, most Staph aureus some Strep pyogenes, red macule --> vesicle or pustule --> honey crust Bullous: all Staph aureus (bullous from toxin), most common in neonates, vesicle --> bulla --> dry erosion |
| Mupirocin 2% ointment is used for... | Impetigo |
| Pseudomonas aeruginosa Gram -ve or +ve? | Negative |
| Pseudomonal Folliculitis (organism, source, innoculation/infection site, time course, tx) | Cause: Gram -ve Pseudomonas aeruginosa Source: hot tubs Innoculation/infection site: hair follicles (erythematous papules/pustules) Time course: starts 8-48h after exposure --> self limited to 7-14days Tx: fluoroquinolone if widespread or immunosuppressed |
| Borrelia burgdorferi (bore-rel-lia berg-dorf-furry) causes... | Lyme disease (Spirochette from Ixodes tick bite) |
| Lyme Disease (organism, skin manifestation, other sx, time course, tx) | Organism: Borrelia burgdorferi (spirochette from Ixodes tick bite) Skin: red macule --> papule --> expanding annular plaque/erythema migran Other sx: other skin sx (edematous, vesicular, crusted), fatique, headache, arthralgias, myalgias Time course: sx 2wks after bite Tx: antibiotics (doxycyclin, amoxicillin) |
| Primary HSV (skin manifestations, other sx) | Most infections are asymptomatic! Skin: grouped vesicles --> pustules/ulcerations --> crusts (generally more severe than recurrent) Other sx: pain, tenderness, burning, malaise, fever, lymphadenopathy |
| Recurrent HSV (skin manifestations, latency establishment, triggers, other sx) | Skin: grouped vesicles/pustules (generally less severe than primary) Latency: DRG Triggers: stress, sun, fever, immunosuppression Other sx: prodrome pain, tenderness, burning |
| Chickenpox (organism, transmission, prodrome, skin manifestations) | Organism: varicella zoster virus (VZV) Transmission: airborne droplets, direct contact w vesicle fluid (infectious til all lesion crusted) Prodrome: 2-3days fever, malaise, myalgia Skin: red macules/papules --> vesicles (dew on rose) --> pustules --> crusts; all stages present; start on scalp/face --> trunk --> extremities |
| Shingles (organism, latency, prodrome, skin manifestations, tx) | AKA: Herpes Zoster Organism: varicella zoster virus (VZV) Latency: DRG Prodrome: intense pain, itching, tingling, tenderness Skin: painful grouped vesicles on erythematous base along sensory dermatome --> crusts Tx: antivirals |
| Erythema infectiosum (organism, host, transmission, population, skin manifestation) | Organism: Parvovirus B19 Host: RBC precursors (causes pancytopenia) Transmission: respiratory droplets Population: school-age children Skin: initial bright red macular erythema on cheeks (slapped checks) --> reticular rash on extremities 1-4days later |
| Cercarial (sir-carry-al) Dermatitis (organism, skin manifestation) | AKA: Swimmer's itch Organism: worm (animal schistosome: cercariae suppose to infect duck; cercariae die when infect humans) Skin: Inflammation --> erythematous papule (Life cycle: egg from duck --> hatch to miracidia --> infect snail & become cercariae --> cercariae infect duck) |
| Scabies (organism, skin sx, dx, tx) | Organism: mite (Sarcoptes scabiei var hominis) Skin: serpiginous/linear lesion, papule, pustule from mite burrowing, laying eggs; intense itching Dx: mineral oil microscope exam of skin scraping; look for adult mites, eggs, fecal pellets Tx: topical scapicide |
| Brown recluse spider bite (organism, location, skin sx, other sx) | Organism: toxic venom from Loxosceles (lox-sauce-so-lees) reclusa bite (dark brown fiddle on cephalothorax) Location: South Central US in woodpiles & attics Skin: dermonecrosis (erosion/ulceration) from toxic venom Other (rarer) sx: shock, hemolysis, renal insufficiency, DIC |
| Delusions of parasitosis | Monosymptomatic hypochondriacal psychosis False belief of parasite infection (bring ziploc, matchbox of skin samples) May experience biting, crawling, stinging Must exclude drug abuse, true derm disorder Tx: antipsychotics |
| Dermatitis artefacta | Skin finding of neuropsychiatic disease |
| Osler nodes vs Janeway lesions | Osler: painful Janeway: not painful (Janeway pain away) |
| Roth spots | Retinal hemorrhages |
| Lupus pernio | Sarcoidosis |
| Retinoids | (Reverse keratinization) Reteinoic acid (tretinoid) Adapalene Tazatotene |
| Antibio/microbes | Erythromycin Clindamycin Sodium sulfacetamide-sulfur Benzoyl peroxide (break comedones too) |
| Salicyclic acid | keratolytic |
| Azelaic acid | keratolytic + anti-inflammatory |
| Dapsone | helpful for inflammatory papules & pustules |
| Oral antibiotics for acne | Tetracycline class Erythromycin |
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