Dermatopathology Flashcards
Functions of the Skin
Prevent fluid loss Protection barrier Area for heat exchange Protects against invading microorganisms Neurological receptor relay system: touch, pressure, temp, pain Vitamin D synthesis
Four Types of Skin Cells
Keratinocytes
Melanocytes
Merkel’s cells
Langerhans’s cells
What is the predominant cell of the epidermis?
Keratinocytes
What happens to the keratinocytes as they move superficially?
Change size
Change shape
What is keratin essential for?
Protective function of the skin
Is the structure protein of hair & nails
Five Layers of Keratinocytes
Stratum germinativum OR stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum
Define Stratum Germinativum or Stratum Basale
Single layer of columnar cells, undergo mitosis, no migration
Define Stratum Spinosum
Two to four layers, cells differentiate
Define Stratum Granulosum
Only a few layers, most differentiated
Define Stratum Lucidum
Thin, transparent, layer mostly confined to the palms of the hand & soles of feet, transitional cells
Define Stratum Corneum
Many layers, dead squamous-type keratinized cells
Where are melanocytes located?
At or in the basal layer
What is the primary function of melanocytes?
Protect from UV rays
What do merkel cells function as?
Mechanoreceptors: touch receptors
Where are Langerhans’ cells located?
Scattered in the supra basal layer of the epidermis
What are Langerhans’ cells responsible for?
Recognizing foreign antigens harmful to the body
Define Dermis
Connective tissue layer separating the epidermis from the subcutaneous fat layer
What is the dermis mostly composed of?
Collagen
Variety of immune cells
Nerves
Blood vessels
What does the subcutaneous tissue consist of?
Primarily fat & connective tissues that lend support to the vascular & neural structures supplying the dermis & epidermis
Examples of Skin Appendages
Sweats glands
Sebaceous glands
Hair Nails
2 Types of Sweat Glands
Eccrine (Merocrine)
Apocrines
Location of Eccrine/Merocrine Sweat Glands
Entire body surface
Originate in dermis & open directly to the skin surface
Primary Function of Eccrine/Merocrine Sweat Glands
Transport sweat to body surface to regulate body temperature
Location of Apocrine Sweat Glands
Deep dermal layer
Characteristics of Apocrine Sweat Glands
Open through hair follicle
Secrete an oily substance
Where are sebaceous glands located?
Over entire skin surface except for the palms, soles, and side of feet
What do sebaceous glands secrete?
Sebum: lipids, cholesterol, & other substances
Function of Sebaceous Glands
Lubricate hair & skin
What does the hair structure consist of?
Hair follicle & hair shaft
Sebaceous gland
Hair muscle (arrector pili muscle)
Apocrine gland (sometimes)
What determines hair color?
Melanocytes within the bulb
Where is the arrector pili muscle located?
Under the sebaceous gland
Define Nails
Hardened keratinized plates
Define Eponychium
Cuticle
Define Rash
Change of the skin affecting color, appearance, and texture
Manifestation of Primary Lesions
Arise from previously normal skin
Manifestation of Secondary Lesions
Created by another process such as scratching or infection
Types of Primary Lesions
Macule Patch Papule Plaque Nodule Tumor Wheal Vesicle Bulla Pustule
Define Macule
Small
Define Patch
> 1 cm
Circumscribed, flat, non-palpable changes in skin color
Ex: vitligo
Define Papule
Elevated solid lesion with variable color
Define Plaque
Flat, elevated surface
> 1 cm
Formed by coalescence of papules
Palpable elevated solid mass
Define Nodule
0.5-2 cm
Deeper and firmer than a papule
Palpable elevated solid mass
Define Tumor
Larger than 1-2 cm
Palpable elevated solid mass
Define Wheal
Somewhat irregular, relatively transient, superficial area of localized skin edema
Palpable elevated solid mass
Ex: mosquito bite, hives
Define Vesicle
Fluid filled lesion up to 1 cm
Define Bulla
> 1 cm
Filled with serous fluid
Circumscribed superficial elevations of the skin formed by free fluid in a cavity within the skin layers
Ex: 2nd-degree burn
Define Pustule
Filled with pus
Circumscribed superficial elevations of the skin formed by free fluid in a cavity within the skin layers
Ex: acne, impetigo
Types of Secondary Lesions
Scales Crust Erosion Ulcer Fissures Atrophy Scar
Define Scales
Abnormal stratum corneum due to accumulation of, or increased shedding of keratinocytes
Define Crusts
Dried serum, pus, or blood
Pt. Hx reveals wheeping, pus, or blood
Define Erosion
Partial loss of the epidermis
Doesn’t penetrate beneath dermal-epidermal border
Heals without scarring
Define Ulcer
Full thickness loss of epidermis & at least some of the dermis, sometimes all of the dermis
Heals with scarring
Define Fissures
Linear splits in the epidermis & may include the dermis
Usually occurs at an orifice, over a joint, or along skin creases
Define Atrophy
Depression of the skin surface due to thinning of the epidermis or dermis
Blood vessels can frequently be seen
Define Scar
Abnormal collection of connective tissue implying injury
Initially thick & pink
Over time becomes white & atrophic
Other Skin Lesions & Descriptive Terms
Excoriation Comedones Milia Cyst Abscess Burrow Lichenification Umbilicated Telangiectasia Petechia Purpura Keratin horn Warty/papillomatous Furuncle Carbuncle
Define Excoriation
Localized damage to the skin due to scratching & consists of linear or pinpoint erosions or crusts
Define Comedones
Plug of sebaceous & keratinized material lodged in opening of hair follicle
Black head: open comedone
White head: closed comedone
Define Milia
Small, superficial keratin cyst with no visible opening
Define Cyst
Cavity lined with epithelium containing fluid, pus, or keratin
Define Abscess
Infected lesion surrounded by a membrane & filled with exudate
Define Burrow
Narrow, elevated, tortuous channel produced by a parasite
Define Lichenification
Thickening of the epidermis with increased skin markings due to persistent scratching
Skin lines accentuated
Define Umbilicated
Surface contains a rounded depression in the center
Define Telangiectasia
Dilated superficial blood vessels
Define Petechia
Circumscribed deposit of blood
Define Ecchymosis
Circumscribed deposit of blood > 0.5 cm
Define Keratin Horn
Accumulation of abnormal keratin which is usually rough on palpation & difficult to remove
Define Warty/ Papillomatous
Surface consists of minute finger-like or round projections
Define Furuncle (Boil)
Skin disease caused by the inflammation of hair follicles
Results in localized accumulation of pus & dead tissue
Define Carbuncle
Interconnected network of furuncles
Distribution Terms
Symmetrical Asymmetrical Sun exposed areas Intertriginous Contact areas Extensor surfaces Flexural surfaces
Define Symmetrical
Involves both sides of body to a similar extent
Ex: acne, psoriasis
Define Asymmetrical
Involves predominantly one side
Examples of Sun Exposed Areas
Sunburns
Photosensitivity
Example of Intertriginous
Candidal rash
Development of Candida in the skin grooves
Ex: rash at top of but crack
Example of Contact Areas
Contact dermatitis
Example of a Skin Condition on the Extensor Surfaces
Psoriasis
Example of a Skin Condition on the Flexural Surfaces
Atopic dermatitis
Types of Margination
Sharp, well defined, or circumscribed
Poorly defined
Sharp, Well Defined, or Circumscribed Skin Issues
Able to draw a line around it
Transition quickly
Poorly Defined Skin Issues
Borders that merge into normal skin
Transition over 1 mm
Shapes of Skin Lesions
Annular Arcuate Iris Nummular Serpiginous Guttate Morbilliform
Describe Annular Shape
Ring-shaped with active margin & clear center
Ex: ring worm
Describe Arcuate Shape
Arched
Bow-shaped
Describe Iris Shape
Target lesion
Describe Discoid Shape
Disk-shaped
Describe Nummular Shape
Coin-shaped
Describe Serpiginous Shape
Snake-like
Describe Guttate Shape
Drop-sized
Describe Mobilliform Shape
Small confluent macules, forming irregular shapes
Types of Arrangements
Confluent Discrete Generalized or diffuse Disseminated Grouped Reticulated
Describe Confluent Arrangements
Blending into adjacent lesions
Describe Discrete Arrangements
Separated by normal skin from other similar lesions
Describe Generalized or Diffuse Arrangements
Covering most of the designated body surface
Describe Disseminated Arrangements
Widespread discrete lesions
Describe Grouped Arrangements
Multiple lesions clustered in one area
Not necessarily blending with each other
Describe Reticulated Arrangements
In the form of a network
Ex: mottled appearance
Palpation Events
Smooth
Uneven
Rough
Describe Smooth Palpation of the Skin
Normal epidermis
Describe Uneven Palpation of the Skin
Scaly, warty, etc.
Describe Rough Palpation of the Skin
Sandpaper like
Ex: keratin horn, scarlatiniform rash, crust