Skin Pathology Flashcards
1
Q
What is a macule?
A
Flat lesion w/ well-circumscried change in skin color
2
Q
What is a Patch?
A
macule >5mm Ex) large brithmark (congenital nevus)
3
Q
What is a papule?
A
Elevated solid skin lesion < 5mm
Ex) Mole (nevus), acne
4
Q
What is a Plaque?
A
Papule >5mm
ex) psoriasis
5
Q
What is a vesicle?
A
Small fluid-containing blister
ex) Chickenpox (varicella), shingles (zoster)
6
Q
What is Bulla?
A
Large fluid-containing blister >5mm
ex) Bullous pemphigoid
7
Q
What is a pustule?
A
Vesicle containing pus
ex) Pustular psoriasis
8
Q
What is a Wheal?
A
Transient smooth papule or plaque
ex) Hives (urticaria)
9
Q
What is a Scale?
A
Flaking off of stratum corenum
ex) eczema, psoriasis, SCC
10
Q
What is a Crust?
A
Dry exudate
ex) Impetigo
11
Q
What is Hyperkaratosis?
A
Inc thickness of stratum corneum
ex) psoriasis
12
Q
What is parakeratosis?
A
Hyperkaratosis w/ retention of nuclei in stratum corneum
ex) psoriasis
13
Q
What is Acantholysis?
A
Separation of epidermal cells
ex) Pemphigus vulgaris
14
Q
What is Acanthosis?
A
Epidermal hyperplasia (inc spinosum)
ex) Acanthosis nigricans
15
Q
What is Dermatitis?
A
Inflam of the skin
ex) Atopic dermatitis
16
Q
What is Albinism?
A
Normal melanocyte # w/ dec melanin production d/t dec tyrosinase activity. Can also be caused by failure of neural cress cell migration during dev. Ocular & oculocutaneous forms
17
Q
What is Melasma (chloasma)?
A
Hyperpigmentation of cheeks assoc w/ pregnancy (“mask of preg”) or OCP use
18
Q
What is Vitiligo?
A
Irreg areas of complete depigmentation
19
Q
What causes Vitiligo?
A
Autoimmune destruction of melanocytes
20
Q
What are Verrucae?
A
Warts common on hands & feet. Condyloma acuminatum on genitals
21
Q
What causes Verrucae?
A
HPV infection of keratinocytes
22
Q
What do Verrucae look like?
A
Soft, tan-colored, cauliflower-like papules w/ rough surface
23
Q
Histo of verrucae
A
Epidermal hyperplasia, hyperkeratosis, koilocytes*
24
Q
What are Melanoctic nevus?
A
Common mole: benign neoplasm of melanocytes
25
Prognosis of Melanocytic nevus
Benign, but mealonoma can arise in congenital or atypical moles via dysplastic nevus
26
What is an Intradermal nevi?
Papular nevus; junctional component lost; MC in adults
27
What is a Junctional nevi?
* Flat macules
* MC mole in children
* Begin as nests of melanocytes at the dermal-epidermal junction
28
What is Urticaria?
Hives; pruritic wheals that form after mast cell degranulation
29
What is Ephelis?
* Freckle
* Normal # of melanocytes
* Inc melanin pigment
30
What is Atopic dermatitis (eczema)?
Pruritic, erythematous, oozing rash w/ vesicles & edema commonly on skin flexures. Us. on the face in infancy & antecubital fossae therafter. Type I hypersensitivity rxn
31
What is Atopic dermatitis assoc w/?
Other atopic dz- asthma & allergic rhinitis
32
What is allergic contact dermatitis?
Type IV hypersensitivity reaction that follows exposure to allergen. Lesions occur at contact site (nickle, poision ivy, neomyocin). Tx by removal of agent & topical glucocorticoids if needed
33
What is Psoriasis?
Papules & salmon colored plaques w/ silvery scaling, esp on knees & elbows (extensor surfaces)
34
Histo of Psoriasis
* _Acanthosis_- epidermal hyperplasia
* Perakeratotiosis- keratinocyte nuclei retention in stratum corneum--called Munro microabscesses
* Inc stratum spinousm & dec stratum granulosum.
* Elongation of rete ridge (resembles comb)
* Thinning of epidermis above dermal papillae
35
What is Auspitz sign?
Pinpoint bleeding spots from exposure of dermal papillae when scales are scraped off d/t epidermal thinning
36
What is Psoriasis assoc w/?
Nail pitting & psoriatic arthritis
37
What is Seborrheic keratosis?
Flat, greasy pigmented squamous epi prolif w/ keratin-filled cysts (horn cyts). Looks "stuck on". Char by keartin pseudocytes on histo.
38
Where do Seborrheic keratosis lesions occur?
Head, trunk & extremities
39
Who gets Seborrheic keratosis?
Common benign squamous proliferation of older persons
40
What is Leser-Trélat sign?
Sudden appearance of multiple seborrheic keratoses, indicating an underlying malignancy (GI, lymphoid)
41
What is Pemphigus vlugaris?
Potentially fatal autoimmune skin disorder w/ IgG Ab against desmoglein 3 (1 &/or 3), a part of desmosomes (needed for cell adhesion) in stratum spinosum. Presents as skin & oral mucosa bullae.
42
What does immunofluorescense of Pemphigus vulgaris reveal?
IgG surrounding epidermal cells (keratinocytes) in a reticular or "fish net" pattern
43
What does the histo of Pemphigus vulgaris look like?
* Acantholysis (separation) of stratum spinosum keratinocytes resulting in suprabasal blisters
* Basal layers remain attached to BM via hemidesmosomes ("tombstone" appearance)
44
What is Nikolsky's sign?
Separation of epidermis upon manual stroking of skin. Thin walled bullae rupture easily→ shallow erosions w/ dried crusts. + in Pemphigus vulgaris
45
What is bullous pemphigoid?
Autoimmune disorder w/ IgG ab against hemidesmosomes b/w basal cells & BM.
46
What does Bullous pemphigoid show on immunoflurorescence?
Highlights IgG along BM→ Linear pattern
47
What are the clinical characteristics of Bullous pemphigoid?
* Eosinophils w/in the tense blisters (don't rupture)
* Similar to but less severe than pemphigus vulgaris- affects skin but spares oral mucosa.
* Negative nikolsky's sign
48
What is Dermatis herpetiformis?
Pruritic papules, vesicles & bullae that are grouped (herpetiform). Deposits of IgA at the tips of dermal papillae.
49
What is Dermatitis herpetiformis assoc w/?
Celica dz (resolves w/ gluten-free diet)
50
What is Erythema mutliforme assoc w/?
Infections (Mycoplasma pneumonia, HSV\*\* MC), cancers, autoimmune dz (SLE) & drugs (penicllin, sulfonamides)
51
How does erythema muliforme present?
Hypersensitivity rxn char by multiple types of lesions- macules, papules, vesicles & target lesions
52
What does a target ring look like?
Targets w/ muliple rings & a dusky center showing epi disruption (d/t central epidermal necrosis surrounded by erythema)
53
What is Stevens-Johnson synd characterized by?
* Fever
* Bulla formation- oral mucosa/lip
* Necrosis
* Sloughing of skin
* High mortality rate
54
What does Stevens-Johnson synd look like?
Typicaly 2 mucous mem involved & skin lesions maybe appear like targets as seen in erythema multiforme
55
What is Stevens-Johnson synd assoc w/?
Adverse drug reaction
56
What is Toxic epidermal necrolysis?
A more severe form of Stevens-Johnson synd w/ \>30% of the body surface area involved. Destroys the epidermal-dermal junction causing diffuse sloughing of skin, resembling a large burn
57
What is acanthosis nigricans?
Epidermal hyperplasia causing symmetrical, hyperpigmented, velvety thickening of skin, esp on neck, axilla or groin
58
What is aconathosis nigricans assoc w/?
Hyperinsulinemia (DM, obesity, Cushing's synd) & visceral malignancy (esp gastric CA)
59
What is actinic keratosis?
premalignant lesions caused by sun exposure
60
What does actinic keratosis look like?
Small, scaly/rough, erythematous or brownish papules or plaques often on face, back or neck
61
What is actinic keratosis a risk for?
Risk of SCC is proportional to degree of epi dysplasia
62
What is erythema nodosum?
Inflam lesions of SQ fat, usually on anterior shins
63
What is erythema nodosum assoc w/?
Sarcoidosis, coccidioidomyocosis, histoplasmosis, TB, strep infections, leprosy & Chron's dz
64
What are the 6 **P**'s of Lichen Planus?
**P**ruritic, **P**urple, **P**olygonal **P**lanar **P**apules & **P**laques
Commonly on wrists, elbows & oral mucosa (Wickham striae)
65
Histo of Lichen Planus
"Sawtooth" inflam infilitrate of lymphocytes at dermal-epidermal junction
66
What is Lichen Planus assoc w/?
Hepatitis C
67
What is Pitryiasis rosea?
"Herald patch" followed days later by "Christams tree" distribution. Multiple plaques w/ collarette scale.
68
What is the clinical courseof Pityriasis rosea?
Self resolving in 6-8 weeks
69
How does a sunburn occur?
UV irradiation causes DNA mut, inducing apoptosis of keratinocytes
70
Which UV irradiation is dominant in tanning & photoaging?
UVA
71
Which UV irradiation is involved in sunburns?
UVB
72
What can sunburns lead to?
Impetigo & skin cancers (basal cell CA, SCC & melanoma)
73
What is Impetigo?
Very superficial skin infection. Highly contagious. Common in children
74
What causes Impetigo?
*S. aureus or S. pyogenes*
75
What does Impetigo look like?
Presents as erythematous macules that progress to pustules,usually on the face. Rupture of pustules results in erosions & dry, "Honey-colored" crusting
76
What is Bullous impetigo?
hass bullae & is caused by *S. aureus*
77
What is Cellulitis?
Acute, painful, spreading infection of dermis & SQ tissues. Presents as red, tender swollen rash w/ fever
78
What causes cellulitis?
*S. pyogenes or S. aureus* that starts w/ a break in skin from trauma, surgery or insect bite
79
What is Necrotizing fascitis?
Necrosis of SQ tissue, usually from anaerobic bacteria or *S. pyogenes*. "Flesh-eating bacteria"
80
What does Necrotizing fasciitis cause?
Results in crepitus (bubbles of gas under skin) from methane & CO2 production. Causes bullae & a purple color to the skin. Surgical emergency
81
What is Staphylococcal scalded skin synd (SSSS)?
*S. aureus* exfolative exotoxins A & B destroy keratinocyte attachments in stratum granulosum only
82
What is Staph scalded skin synd (SSSS) characterized by?
Fever & gen erythematous rash w/ sloughing of upper layers of the epidermis that heals completely
83
Who is SSSS seen in?
Newborns & children
84
What is hairy leukoplakia?
White painless plaques on the tongue that cannot be scraped off
85
What is hairy leukoplakia mediated by?
EBV
86
Who gets hairy leukoplakia?
HIV + pts
87
What is the MC skin cancer?
Basal cell CA
88
Where is Basal cell CA found?
Sun-exposed areas of body. Classic location is UPPER lip
89
What is the clinical course of Basal Cell CA?
Locally invasive but almost never mets. Excellent prognosis
90
What does Basal Cell CA look like?
Pink, pearly nodules\*, commonly w/ telangiectasias\*, rolled borders, & central crusting or ulceration. Also appear as nonhealing ulcers w/ infiltrating growth or as a scaling plaque (superficial BCC)
91
What is the histo of Basal Cell tumors?
Nodules of basal cells w/ palisading peripheral nuclei\*
92
What is the 2nd MC skin cancer?
SCC
93
What is SCC assoc w/?
Excessive exposure to sunlight, albinism, xeoderma pigmentosum, chronic inflam, immunosuppression, & occasionaly arsenic exposure
94
Where does SCC occur?
Appears on face, LOWER lip, ears & hands
95
What is the clincial course of SCC?
Locally invasive, but may spread to LN & will rarely mets. assoc w/ chronic draining sinuses
96
What do SCC lesions look like?
Ulcerative red lesions/ nodular mass w/ freq scale
97
What is the histopathology of SCC?
Keratin pearls
98
What is Keratoacanthoma?
Well diff SCC variant that grows rapidly (4-6 weeks) & may regress spon over months. Presents as a "cup-shaped" tumor filled w/ keratin debris.
99
What is Melanoma?
Common tumor w/ significant risk of mets. MC COD from skin cancer
100
What is the tumor marker for Melanoma?
S-100
101
What are the risk factors for melanoma?
* Prolonged sunlight exposure
* Albinism
* Xeroderma pigmentosum
* Dysplastic nevus synd
102
What does the depth of melanoma correlate w/?
Risk of mets
103
What are the **ABCDE**s of melanoma?
* **A**symmetry
* **B**order irreg
* **C**olor variation
* **D**iameter \>6mm
* **E**volution over time
104
What mut is melanoma driven by?
Activating mut in BRAF kinase
105
What is the 1º tx of melanoma?
Excision w/ appropriately wide margins
106
What can pts w/ melanoma w/ BRAF V600E mut be tx w/?
May benefit from vemurafenib, a BRAF kinase inhibitor
107
What is the Epidermis composed of?
Keratinocytes & has 4 layers (basalis, spinosum, granulosum & corneum)
108
What is the stratum basalis?
Regenerative (stem cell ) layer
109
What is the stratum spinosum char by?
Desmosomes b/w keratinocytes
110
What is the stratum granulosum char by?
Granules in keratinocytes
111
What is the stratum corneum char by?
Keratin in anucleate cells
112
What does the Dermis consist of?
CT, nerve endings, blood & lymphatic vessels & adnexal structures (hair shafts, sweat glands, & sebaceous glands)
113
What is acne vulgaris?
Comedones (whiteheads/blackheads), pustules (pimples) & nodules (scars). Extremely common in adolescents
114
What is the cause of acne vulgaris?
* Hormone assoc inc in sebum production & excess keratin production blocks follicles forming comedones
* Propionibacterium acnes infection produces lipases that break down sebum, releasing proinflam FA's that resutls in pustule or nodule formation
115
What is the tx of acne vulgaris?
Benzoyl peroxide (antimicrobial) & vit A derivatives (isotretinoin) which reduce keratin prod
116
What is Wickham striae?
Lichen planus that looks like reticular white lines on the oral mucosa
117
What is xeroderm pigmentosa?
AR defect in nucleated excisor enzymes needed to repair pyrimadine dimers (DNA damage) caused by UVB light exposure
118
What is responsible for skin pigmentation?
Melanocytes in basal layer of epidermis
119
Where are melanocytes derived from?
Neural crest
120
How is melanin synthesized?
Synthesized in melanosomes\* using tyrosine as a precursor molecule. Pass melanosomes to keratinocytes to cause skin pigmentation.
121
What does Albinism inc risk of?
* SCC
* Basal Cell CA
* Melanoma
* Due to dec protection against UVB (inc pyrimidine dimers)
122
What does a freckle look like?
Small, tan to brown macule; darkens when exposed to sunlight.
123
What are freckles caused by?
Inc # of melanosomes (melanocytes are NOT inc)
124
What is a compound nevi?
Benign nests of melanocytes extend from the epidermal-dermal junction into the dermis
125
What is dysplastic nevus syndrome?
AD disorder char by formation of dysplastic nevi that may progress to melanoma
126
What are the variants of melanoma?
* Superficial spreading
* Lentigo maligna melanoma
* Nodular
* Acral lentiginous
127
What is superficial spreading melanoma variant?
MC subtype, dominant early raidal growth results in good prognosis
128
What is the Lentigo maligna melanoma variant?
Letiginous proliferation (radial growth) w/ good prognosis
129
What is the Nodular melanoma variant?
Early vertical growth that pushes the epidermis up to form a nodule; poor prognosis
130
What is the Acral lentiginous melanoma variant?
* Arises on the palms or soles; under proximal nail beds
* Often in dark-skinned individuals (African Am, Asians)
* NOT related to UV light exposure
131
What is the radial growth of melanoma?
Horizontal growth along the epidermis & superficial dermis. Low risk of mets
132
What is the Vertical growth of melanoma?
Growth deep into the dermis. Inc risk of mets
133
What is Breslow thickness?
Most important prognostic factor in predicting melanoma mets--depth of tumor growth.
134
What is Molluscum Contagiosum?
Firm, pink, umbillicated papules d/t poxvirus (DNA virus)
135
What is the histo of Molluscum Contagiosum?
Affected keratinocytes show cytoplasmic inclusions (molluscum bodies\*)
136
Who gets Molluscum contagiosum?
Most often arise in children; also occur in sexually active & immunocompromised pts
137
What is Daurier's Sign?
Dermal edema resembling a hive from localized stroking of an area of skin w/ a pointed insturment (Uticaria; Type I hypersensitivity)
138
What is Koebner's phenomenon?
Rash develops in areas of trauma
