Skin Pathology Flashcards
what is a macule
primary lesion; small flat (less than 1cm)
what is a patch
primary lesion; large flat (greater than 1 cm)
what is a papule
primary lesion; raised (smaller than 1 cm)
what is a plaque
primary lesion; raised (greater than 1 cm)
what is a vesicle
primary lesion; small, clear fluid filled (less than 1 cm)
what is a tumor/mass
primary lesion; raised, deep, and greater than 2 cm
what is a pustule
primary lesion; white fluid filled
what is a bulla
primary lesion; large, clear fluid filled (greater than 1 cm)
mechanism of papule or plaque formation
proliferation of cells in epidermis or superficial dermis
what is a nodule
primary lesion; usually greater than 1 cm, deep and palpable
mechanism of nodule formation
proliferation of cells into the mid-deep dermis or fat
erythematous means
red FROM inflammation
additional descriptors for primary lesions
- color
- size
- texture
what is scale
secondary change; accumulated skin (stratum corneum)
what is crust
secondary change; died exudate: blood, serum, pus
scab
what is excoriation
secondary change; traumatized due to scratching
what is erosion
secondary change; depression with loss of epidermis (superficial)
what is ulceration
secondary change; depression with loss of epidermis and dermis (deeper than erosion)
what is fissure
secondary change; linear cleavage
what is lichenification
secondary change; thickening, accentuated skin line
what is atrophy
secondary change; depression, thinning, wrinkling
what is scar
secondary change; permanent fibrotic change
if something is vascular/vasculitic it will not
blanch with pressure
petechiae/petechial is a secondary descriptor. what does it mean
acute to subacute leakage of capillaries within skin; generally pinpoint to small
purpura/purpuric is a secondary descriptor. what does it mean
acute to subacute leakage of capillaries or small-larger vessels within skin; usually larger; may be palpable
ecchymotic is a secondary descriptor. what does it mean
subacute to chronic hemorrhage within skin; usually larger
examples of configuration
•solitary •discrete •annular •confluent/coalescent •clustered/grouped •linear reticular (net-like)
what does the term acral mean in the context of distribution pattern
the most distal part (hands, feet, tip of nose)
how to describe skin findings
distribution, configuration, color/size primary lesion with +/- secondary change
causes of impetigo
- staph aureus (more common)
* strep pyogenes
common location of impetigo
around mouth or perineum
description of impetigo
crusted, “glazed” eroded papule to plaque, peripheral rim of scale
uncommonly bullous -> blisters
impetigo can be tender or asymptomatic. how is it treated
topical or oral abx
impetigo is rarely biopsies, but what would be seen histologically
subcorneal neutrophils and scattered gram + cocci
usually doesn’t invade beyond epidermis
description of cellulitis
- edematous, erythematous, warm, sometimes taut/shiny localized plaque
- usually solitary
- uncommonly blisters surface due to edema
cellulitis may be present with or without fever and other systemic sxs. what is the treatment
- systemic abx (PO or IV)
* rest elevation
necrotizing fasciitis is usually deeper tissue injury than cellulitis. what usually causes it
anaerobic bacteria or group A strep pyogenes
description of necrotizing fasciitis
purple, dusky necrotic color +/- ulcers and bullae
necrotizing fasciitis is a surgical emergency and is associated with
severe, intense pain and systemic symptoms
In staph scalded skin syndrome, staph aureus produces
epidermolytic-toxin that causes cleavage/split within epidermis
what demographic is typically affected by SSSS, and why?
- infants and younger kids b/c they have physiologically decreased renal function
- also those who are immunocompromised
those affected by SSSS are usually febrile and have peeling that is accentuated at perioral areas and body folds. where is the most common primary infection?
nasopharynx
why is the area of primary infection important in staph scaled skin?
that is the area that must be cultured
SSSS doesn’t have any true mucosal involvement. what is the treatment?
systemic anti-staphylococcal abx (PO or IV)
histologically how could a biopsy of SSSS be differentiated from impetigo?
there are no organisms in the subcorneal blister of SSSS because it is a toxin-mediated effect
what are they cytopathic effect of herpes virus on keratinocytes?
the 3 Ms
•margination of chromatin
•multinucleation
•molding of nuclei (clumping together)
HSV1 more commonly affects
oral
HSV2 more commonly affects
genital
initial infection of HSV can range from
asymptomatic to fulminant stomatitis (rare)
Description of shingles (VZV) rash
- dermatomal distribution disseminated papules, vesicles, plaques, bulla
- itchy, painful
- +/- systemic symptoms
concerning presentations of VZV
- ophthalmic involvement -> possible blindness
* Ramsay-hunt syndrome -> facial palsy, ear pain
Histopathology of VZV
identical to HSV! 3Ms
Need PCR to discriminate between the 2
what are verruca and what the cause
warts; HPV
vulgaris verruca
common wart
condyloma acuminata
genital warts
histology of verruca vulgaris
- papillomatous epidermal acanthosis
- hyperkeratosis
- hypergranulosis
what is molluscum contagiousum
in the pox virus category
description of molluscum contagiosum
•dome-shaped papules with waxy surface •single or multiple •may be pruritic •~5mm "papule with central umbilication"
what is seen histologically in molluscum contagiosum
henderson-patterson bodies = accumulation of virus into brick-like structures
location of molluscum contagiosum lesions
trunk, face, axillae, genital area (STI)
how does molluscum contagiosum spread
with scratching
what are tinea
40+ species of fungi that “feed” on dead skin (dermatophyte infection)
species that cause tinea fall in which genera
- tricophyton
- microsporum
- epidermophyton
what stain can be used for tinea
KOH stain the stratum corneum
*fungal culture if inconclusive
fungal forms of tinea can be difficult to see on HandE stain, but what might be identifiable?
altered cornified layer with intracorneal neutrophils
tinea pedis
athlete’s foot
tinea corporis
ringworm occurs anywhere on the body
tinea manuum
hand (usually left)
tinea cruris
jock itch
tinea capitis
scalp
tinea onychomycosis
nails
tinea versicolor (pityrosporum)
not technically tinea, b/c caused by yeas organism, but lumped in because similar presentation
bacterium that causes syphilis
treponema pallidum (spiral shaped bacteria)
primary syphilis infection (treponema pallidum)
solitary or multiple painless genital “chancres”
secondary syphilis infection (treponema pallidum)
rash and condyloma lata, systemic symptoms, moth-eaten alopecia
tertiary syphilis infection (treponema pallidum)
gummas (granumolas), aortitis, neurosyphilis, etc
congenital syphilis (treponema pallidum)
stillbirth, acral bullae/erosions, rhinitis, rhagades, deafness
*highly infectious
what is sarcoptes scabiei
the human itch mite
an arthropod that burrows under the skin and causes scabies
scabies infection occurs when
adult female sarcoptes scabiei burrows into the epidermis and lays eggs
transmission of scabies
close skin contact
description of scabies
- usually exceedingly pruritic
* moth-eaten papules, burrows
what histologic prep may be useful in diagnosing scabies?
mineral oil prep
where does scabies infection occur
- hands, feet, waistline/genitals
* infants may have atypical presentation
cutaneous infections caused by arthropod
scabies
cutaneous infections caused by bacteria
impetigo, cellulitis, SSSS
syphilis (treponema=spiral bacteria)
cutaneous infections caused by dermatohyte (fungus)
tinea
cutaneous infections caused by virus
HSV, VSV, molluscum contagiosum
subcutis is underneath the dermis and is also called
panniculus
stratum corneum
- composed of dead, anucleated keratinocytes
* protects against environment and external pathogens
stratum lucidum is only normally found
•on thickened skin (palms and soles)
stratum granulosum (aka granular layer) have keratinocytes with heratohyalin granules that
are exocytosed to produce a water-proof barrier
stratum spinosum (aka spiny layer)
- provided structural support
* home of langerhans cells
cellular junctions in stratum spinosum
desmosomes (have pairs), look like spines
stratum basale (basal layer)
- connects epidermis to dermis
* home of melanocytes and stem cells
cellular junctions in stratum basale
hemidesmosome (no pairs)
merkle cells are somewhat of a mystery but serve the purpose of
group together to form a receptor for touch (sustained pressure/deep static touch)
melanocytes are derived from
neural crest
langerhans cells are located in stratum spinosum and act as
- antigen presenting cells (APCs)
* mediators of immune response
langerhans cells contain
birbeck granules, which look like tennis rackets
what is found only in the dermis, and not the epidermis
blood vessels, lymphatics, and nerves
fibroblasts are the main cells of the dermis and produce
collagen, elastin, and ground substance
free nerve endings in the dermis have 2 kinds
- c-type: small, slow, unmyelinated
* A delta type: small, fast, myelinated
meissner corpuscles sense what in dermis
light touch, vibration, and position
pacinian corpuscles sense what in dermis
vibration and pressure