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MSK Personal > Dermatology > Flashcards

Dermatology Flashcards

1
Q

What are the functions of the skin?

A

Protection (against damage, water loss, radiation, and disease)

Sensation (specialized nerve cells communicate stimuli)

Sexual signaling (Health communicated by appearance)

Metabolism (Synthesizes vitamin D3 which is importnat in proper bone formation)

Thermoregulation (Capillaries in the papillary dermis)

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2
Q

What are the features of the stratum basale?

A

Single layer of basophilic cuboidal cells

Attached to basement membrane (hemidesmosomes)

Attached to each other (desmosomes)

Intense mitotic activity (Progenitor cells for all layers)

Keratinocytes have keratin which increases in amount an crosslinking as cells move superficially

Friction blisters occur between S. Basale and basement

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3
Q

What are the features of the S. Spinosum?

A

Desmosomes between keratinocytes give a spiny appearance

Thickest layer

Typically the last mitotic layer

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4
Q

What are the features of the S. Grunulosum

A

Three to five layers of flattened highly basophilic cells

Basophilic masses are called keratohyaline granules

Also have golgi derived lamellar granules which are responsible for secreting lipid rich waterproof layer around cells

Keratinization in conjunction this layer help prevent water loss

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5
Q

What are features of the S. Lucidum

A

Only found in thick skin

Translucent layer of flattened keratinocytes held together by desmosomes

Cytoplasm consists almost exclusively of densely packed keratin

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6
Q

Features of the Stratum Corneum

A

15-20 layers of squamous cells filled with filamentous keratins

By this time tonofibrils have massed with filagrins and are just one mass with the keratohyaline granules

Amorphous proteinaceous cells are called squames and are continuously lost

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7
Q

What are melanocytes?

A

Derivatives of neural crest cells responsible for production of melanin and carotenes which color the skin

Tyrosine converted to DOPA which is converted to melanin

Affected in albinism or vitiligo

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8
Q

How does tanning occur?

A

Tanning is a two stage process that darkens the existing melanin and causes the melanocytes to produce more melanin which can then build up in the keratinocytes

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9
Q

What are langerhans cells?

A

The dendritic cells of the epidermis

Represent 2-8% of epidermal cells

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10
Q

What are Merkel Cells?

A

Epithelial tactile cells

Sensitive mechanoreceptors for light touch

Abundant in sensitive skin like that of the fingertips

Derive from basal layer stem cells

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11
Q

What is the dermis?

A

Layer of connective tissue beneath the epidermis

Connects epidermis to the hypodermis

Used to make leather

Thickest in the back at 4mm

Papillary layer and reticular layer

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12
Q

What is important about the subcutaneous layer?

A

Consists of loose connective tissue

Also called superficial fascia

Cotains adipocytes (good fat) which can be used in metabolism

Extensive vascular supply promotes rapic uptake of insulin or drugs injected into it

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13
Q

What are meissner’s corpuscles?

A

Phasic mechanoreceptors

present in the dermal papillae

light touch or low frequency stimuli

Numerous in fingertips but decline slowly with age

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14
Q

Pascinian Corpuscles

A

Large oval structures deep within reticular dermis

Specialized for course touch, pressure, and vibrations

Phasic receptors

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15
Q

Describe a hair follicle from inside to outside

A

Medulla (Highly Keratinized)

Cortex (Highly Keratinized)

Cuticle (continuous with internal root sheath at level of hair bulb)

Internal root sheath (disappears just above attached sebacous gland)

External root sheath (continuous with basal layer of surrounding epithelium)

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16
Q

Arrector pili muscle

A

Attached to hair follicle

Contraction causes hair to stand up on end

Contraction also cause sebum to be released from sebaceous glands

17
Q

Nails

A

Keratinized epithelium

Nail root covered by a fold of stratum corneum called eponychium

Nail plate is bound to nail bed which consists of S. Spinosum and S. Basale layers

Continuous growth of nail matrix pushes nail plate out at 1mm/month in toes and 3mm in fingers

18
Q

What are the common sources of skin infections?

A

Endogenous sources (normal flora taking advantage of immunosuppression) (P. Acnes)

Exogenous sources (Bacteria that is aquired from another source)

Toxins (superantigens secreted by bacteria)

19
Q

What are the general characteristics of all streptococci?

A

Gram positive

Catalase negative

Appear in pairs or in chains

Obligate extracellular bacteria

20
Q

What are the characteristics of Group A Strep?

A

Beta Hemolytic

Landsfield A antigen present (tested with rapid antigen test, kinda like pregnancy test)

Bacitracin sensitive

21
Q

How does group A strep avoid being taken up by host neutrophils?

A

M proteins prevent complement fixation

Hyalunonic Acid capsule mimics normal human HA and therefore forces the body to recognize the bug as “self”

22
Q

What are the common supporative GAS diseases?

A

Strep throat

Pyoderma (Impetigo, Erysipilis, Cellulitis, Necrotizing Fascitis)

23
Q

What are common non-supporative sequelae caused by GAS?

A

Acute Rheumatic Fever (if patient develops this they must be put on prophylactic penicillin for the rest of their life to prevent additional cardiac antibodies)

ARF is caused because many M proteins mimic normal proteins in the body like tropomyosin

Glomerular Nephritis

24
Q

How do superantigens from GAS work?

A

They cause bonding between MHC and T cells even when no antigen is present

Locking them together causes the T cells to release TNF-A and IFN y leading to fever

25
Q

What are characteristics of staphylococci?

A

Gram positive

Facultatively anaerobic

Catalase positive

26
Q

What toxin is responsible for Toxic Shock Syndrome?

A

TSST-1

27
Q

Freckles

A

Generally small tan red or light brown macules

Fade and darken in a cyclic fashion

Hyperpigmentation caused by increased production of melanosomes

28
Q

Lentigo

A

Common benign localized hyperplasia of melanocytes

Small oval tan brown macule or patch

Do not darken when exposed to sunlight

Characterized by linear, non-nested, melanocytic hyperplasia

29
Q

Melanocytic Nevus

A

Known colloquially as moles

Benign mutations of the RAS signaling pathway leading to continuous signaling of NRAS or BRAF

Commonly small and uniformly pigmented

May become more prevalent during pregnancy

Junctional become Compound become Intradermal

30
Q

Dysplastic Nevi

A

May be direct precursors of melanoma

May indicate predisposition to melanoma

Increased BRAF activity leads to decreased p16/INK4a activity which leads to increased CDK4 and CDK6 activity

May also be caused by increased TERT

Larger than most nevi and may number in the 100s

Histologically looks lentiginous with melanocytic nests

31
Q

Melanoma

A

The most deadly of all skin cancers

ABCDE, Radial then Vertical Growth,

Measured by Breslow thickness

Strongly linked to UV exposure

CDK2NA gene is often mutated which blocks suppression of CDK4 and CDK6 preventing RB from acting as a tumor suppressor Can also arise from mutations of PTEN or KIT, TERT is most common mutation yet identified

32
Q

Seborrheic Keratoses

A

Have a “stuck on” appearance

Activation of FGFR3 often found

Uniformly hyperpigmented with granular surface

Hyperkeratosis and sometimes horn cysts are noted

Can develop whirling foci when irritated

33
Q

Fibroepithelial Polyp

A

Commonly called a skin tag

Soft, flesh colored, baglike tumor

May undergo torsion causing pain and necessitating removal

Fibrovascular cores covered by benign squamous epithelium

34
Q

Epithelial Inclusion Cyst

A

Formed by invagination and cystic expansion of the epidermis

When “popped” they stink incredibly because of the decomposed keratin inside

35
Q
A

MSK Personal (12 decks)

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