Block 9 - L8, 9, 10 Flashcards
1
Q
What are the 3 layers of the skin (superficial to deep) and how do they appear on H&E stain?
A
- Epidermis (basophilic)
- Dermis (eosinophilic)
- Subcutaneous tissue (clear)
2
Q
What are the 5 layers of the epidermis (superficial to deep)?
A
- Stratum corneum
- Stratum lucidum (in thick skin only)
- Stratum granulosum
- Stratum spinosum
- Stratum basale
3
Q
Where are skin stem cells located?
A
Stratum basale
4
Q
What makes up the stratum spinosum and what is its purpose?
A
Keratinocytes connected by desmosomes - strength
5
Q
What makes up the stratum granulosum and what is its purpose?
A
Lipid envelope and keratohyalin granules - secrete substances that hold the corneum together
6
Q
What is desquamatization?
A
Process of epidermal maturation; layers of the epidermis represent vertical maturation from undifferentiated basal cells to fully differentiated cornified cells
7
Q
How long does it take for the skin to fully mature?
A
25 days
8
Q
Disordered maturation causes ___ due to lack of desquamation.
A
Skin thickening
9
Q
Shorter maturation periods are seen in ___ conditions.
A
Inflammatory
10
Q
List the epithelial cell junctions of the skin.
A
- Tight junction
- Adherens junction
- Desmosome
- Gap junction
- Hemidesmosome
11
Q
What is the role of tight junctions?
A
Seals the gap between epithelial cells, controls water and solutes
12
Q
What is the role of adherens junctions?
A
Connects actin filament bundles in one cell with that in the next cell; strength
13
Q
What is the role of desmosomes?
A
Connect intermediate filaments in one cell to those in the next; strength
14
Q
What is the role of gap junctions?
A
Passage of small water solute molecules between cells; communication
15
Q
What is the role of hemidesmosomes?
A
Anchor intermediate filaments to the ECM (basement membrane)
16
Q
What are the three broad categories of skin pathology?
A
- Tumors
- Rashes
- Infection
17
Q
What is ichthyosis?
A
Defective desquamatization leading to a build up of compacted scales (stratum corneum is retained and thickened)
18
Q
What are the etiologies of ichthyosis?
A
- Ichthyosis vulgaris (AD)
- Congenital ichtyosiform erythroderma (AR)
- Lamellar icthyosis (AR)
- X-linked ichthyosis
19
Q
X-linked ichthyosis involves a deficiency in ___.
A
Steroid sulfatase
20
Q
How does ichthyosis vulgaris appear grossly?
A
Fish-like scales (orthokeratosis)
21
Q
How does ichthyosis vulgaris appear microscopically?
A
Increase/thickening of the stratum corneum
Thinning or loss of the granular layer
22
Q
List the benign epithelial neoplasms involving keratinocytes.
A
- Seborrheic keratosis
- Acanthosis nigricans
- Fibroepithelial polyp/acrochordon/skin tag
23
Q
How does seborrheic keratosis appear grossly?
A
“Stuck-on” verrucous waxy brown papules or plaques
24
Q
Where is seborrheic keratosis found on the body?
A
Anywhere on the skin except for the palms and soles
25
What population (age) gets seborrheic keratosis?
>30 y/o (middle age and up)
26
How does seborrheic keratosis appear histologically?
1. Hyperkeratosis
2. Papillomatosis (undulating appearance - Bart Simpson hair sign)
3. Acanthosis (thickening of the epidermis)
4. Uniform small keratinocytes with a flat base (string sign)
5. Keratin-filled horn cysts
6. Frequent melanin pigment present
27
How does acanthosis nigricans appear grossly?
Poorly defined hyperpigmented verrucous plaques with velvety "scales"
28
Where is acanthosis nigricans found on the body?
Commonly in the creases of the axilla and neck
29
How does acanthosis nigricans appear histologically?
1. Hyperkeratosis
2. Papillomatosis
3. Basal layer hyperpigmentation
30
What population (age) gets acanthosis nigricans - benign type and malignant type?
Benign type: childhood (associated with obesity, endocrine issues, also hereditary)
Malignant type: middle age and up
31
What is the Leser-Trelat sign?
Sudden onset of multiple seborrheic keratoses that may indicate a paraneoplastic syndrome (most common underlying neoplasm - GI)
32
How does an acrochordon appear grossly?
Soft, tan to-flash-colored PEDUNCULATED papule, 1-10 mm in size with a smooth or folded surface
33
Where is acrochordon found on the body?
Axilla, neck, inframammary region, inguinal region, eyelids (areas where there is rubbing)
34
How do acrochordons appear histologically?
1. Polypoid with loose fibrovascular core
2. Papillomatosis
(Also acanthosis and hyperkeratosis)
35
List the pre-malignant and malignant epithelial neoplasms involving keratinocytes.
1. Actinic keratosis
2. Squamous cell carcinoma
3. Basal cell carcinoma
36
What is actinic keratosis?
Common scaly erythematous patch located on sun-damaged skin; increasingly common with age; precursor of SqCC
37
How is actinic keratosis treated?
Cryotherapy or topical chemotherapeutics to prevent progression to SqCC
38
How does actinic keratosis appear grossly?
Ill-defined scaly erythematous macules
39
How does actinic keratosis appear microscopically?
1. Basal layer atypia
| 2. Parakeratosis (epidermal involvement) alternating with orthoparakeratosis (uninvolved hair follicles) - flag sign
40
What defines squamous cell carcinoma in situ?
It is confined to the epidermis - no invasion into the dermis
41
What are the two clinical manifestations of squamous cell carcinoma in situ and how do they appear on histology and grossly?
1. Bowen's disease - single irregulary scaly erythematous plaque
2. Bowenoid papulosis - multiple papules (frequently)
Atypia at all level of the epidermis
42
Where on the body is Bowen's disease found?
Trunk, extremities, face
43
Where on the body is Bowenoid papulosis found and what causes it?
Genital area; HPV-induced
44
How does Bowen's disease appear on histology?
1. Full thickness epidermal atypia
2. Hyperkeratosis
3. Basal layer sparing (eyeliner sign)
4. Involves follicles
45
How common is squamous cell carcinoma of the skin?
2nd most common skin tumor
46
What populations (age, gender) get squamous cell carcinoma of the skin?
Older individuals
| M>F
47
What is the most common cause of squamous cell carcinoma of the skin?
Exposure to UV light, which leads to TP53 mutations at pyrimidine dimers
48
What are other genetic mutations seen in squamous cell carcinoma of the skin?
1. Activating mutations in HRAS
| 2. Loss of function mutations in Notch receptors
49
What are some other causes of squamous cell carcinoma in the skin?
1. Immunosuppression (HPV 5 and 8)
2. Industrial
3. Chronic wounds
4. Burn scars
5. Arsenic
6. Ionizing radiation
50
What percent of squamous cell carcinoma of the skin metastasize?
5% (not frequently metastatic, but it is aggressive)
51
How does squamous cell carcinoma of the skin appear grossly?
Scaly, sometimes ulcerated and verrucous (rough surface) papules and nodules
52
How does squamous cell carcinoma of the skin appear microscopically?
1. Hyperkeratotic acanthotic epidermis with papillomatosis comprised of atypical squamous cells (pinkish) extending from the epidermis invading into the dermis
2. Islands with keratin pearls
3. Uneven base
53
Compare AK, SCCis, and SCC with respect to keratinocyte atypia.
AK - yes, basal layer
SCCis - yes, full thickness
SCC - yes, dermis
54
Compare AK, SCCis, and SCC with respect to dermal invasion.
AK - no
SCCis - no
SCC - yes
55
Compare AK, SCCis, and SCC with respect to involvement of the hair follicle.
AK - no (flag sign)
SCCis - yes
SCC - yes
56
Compare AK, SCCis, and SCC with respect to involvement of the basal layer.
AK - yes
SCCis - no (sparing)
SCC - yes
57
What is the most common invasive cancer in humans?
Basal cell carcinoma
58
What populations get basal cell carcinoma?
Older individuals
Sun-exposed sites
Immunosuppressed
DNA mismatch repair syndromes (xeroderma pigmentosa)
59
What are common mutations seen in basal cell carcinoma?
1. PTCH gene mutations (regulates Hedgehog pathway signaling) - 30%
2. P53 mutations - 40-60%
60
What is Gorlin Syndrome (Nevoid Basal Cell Carcinoma Syndrome)?
AD disorder of multiple BCC before age 20 accompanied by medulloblastomas, ovarian fibromas, odontogenic keratocysts
61
What genetic mutation is associated with Gorlin Syndrome?
PTCH gene on chromosome 9q22.3 (born with 1 hit)
62
How does basal cell carcinoma appear grossly?
Pearly, pink papule with overlying telangiectasia
63
How does basal cell carcinoma appear on histology?
1. Proliferation of basaloid cells (dark, scant cytoplasm, elongated hyperchromatic nuclei)
2. Connection to overlying basal layer
3. Peripheral palisading
4. Peritumoral clefting (artifact)
5. Mucinous alteration of surrounding stroma
6. Prominent dermal telangiectasias
64
What is on the differential for basal cell carcinoma?
Metastatic cancer
65
What are melanocytes?
Clearish cells in the basal layer with dark nuclei that produce melanin
66
What is the normal ratio of melanocytes to keratinocytes?
1:10 (non-sun damaged skin - changes to 1:4 in sun damaged skin)
67
List the pigmented skin disorders of melanocytes.
1. Vitiligo
2. Albinism
3. Melasma
68
How does vitiligo appear grossly?
Well-defined milky-white patches of skin
69
How does vitiligo appear histologically?
Loss of melanocytes seen on IHC stain
70
What is the etiology of vitiligo?
Autoimmune destruction of melanocytes
71
How does albinism appear grossly?
Dilution of the color of the hair, skin, and/or eyes
72
How does albinism appear on histology?
Loss of melanin PIGMENT on IHC stain
73
What is the etiology of albinism?
Decreased tyrosinase activity or defect transport
74
How does melasma appear grossly?
Hyperpigmentation of skin
75
How does melasma appear on histology?
Melanin deposited in basal and suprabasal keratinocytes, melanin in the dermis within melanophases, solar elastosis, elastic fiber fragmentation
76
What is the etiology of melasma?
Pregnancy or OCP use
77
List the neoplasms of melanocytes.
1. Freckle (ephelis)
2. Lentigo
3. Melancoytic nevi
4. Melanoma
78
How do freckles (ephelises) appear grossly?
Small, tan-red to light brown macules on sun-exposed areas; most common lesion of childhood
79
How do freckles appear histologically?
Increased melanin PIGMENT with basal keratinocytes; melanocytes may be enlarged, but normal density
80
How do lentigos appear grossly?
Small, oval tan-brown found at mucus membranes and at any age
81
How do lentigos appear on histology?
Non-confluent typical single cell melanocytic HYPERPLASIA along the basal layer
82
How do melnaocytic nevi (moles) appear grossly?
Tan to brown macules and papules
83
How do COMMON TYPE melanocytic nevi (moles) appear grossly?
Small, well-circumscribed, banal
84
How does melanoma appear grossly?
Most greater than 10 mm, changes in color, size, shape of previous lesions, etc.
85
How does melanoma appear histologically?
Confluent nests and single atypical melanocytes
86
Compare freckles and lentigos.
Freckles: increased MELANIN in keratincoytes
Lentigo: increased MELANOCYTES
87
What are the three different types of benign common nevi and how do they differ?
1. Junctional (majority in the epidermis) - young people
2. Compound (epidermal and dermal components) - middle age people
3. Intradermal (only dermal) - older people
88
How do dysplastic nevi appear grossly?
Usually >5mm, flat to slightly raised macules in sun-exposed and protected areas
89
What are the histologic features of dysplastic nevi?
1. Architectural atypia - melanocytic nests may be larger and fused (bridging) and junctional component extends past dermal components (shouldering)
2. Lamellar fibroplasia
3. Cytologic atypia (enlarged, angulated nuclear contours, hyperchromasia)
90
What is dysplastic nevus syndrome?
Tendency to develop multiple dysplastic nevi and melanoma; 50% have melanoma byage 60
91
What genetic mutations are involved in dysplastic nevus syndrome?
(Autosomal dominant)
CDKN2A gene on chromosome 9p21
CDK4 on chromsome 12q14
92
What % of dysplastic nevi turn into melanoma?
20-30% (same rate as ordinary nevi)
93
Define shouldering.
Epidermal component extends at least 3 rete ridges beyond dermal component
94
Define bridging.
Confluence of rete ridge nests
95
What are the prognostic factors for melanoma?
1. Depth (Breslow thickness)
2. Number of mitotic figures (less important these days)
3. Ulceration
4. Lymph node involvement
5. Regression
6. Tumor infiltrating lymphocytes
7. Gender
8. Location
96
What does a positive sentinel lymph node biopsy indicate?
Melanoma spreading
97
What are the ABCDEs of melanoma?
1. Asymmetrical
2. Border (irregular, notched, blurred, uneven)
3. Color (uneven, may see areas of regression)
4. Diameter (usually larger in diameter than the size of a pencil eraser = 6 mm)
5. Evolving (changes in size, shape, color, eelvation, new symptoms - bleeding, pruritis, pain)
98
How does melanoma in-situ appear on histology?
Confluent proliferation of single and nested atypical melanocytes with upward pagetoid spread
99
How does malignant melanoma appear on histology?
(Shoulder + bridging + atypia + lamellar fibroplasma + confluence + upward pagetoid spread) + invasion of atypical melanocytes into the dermis
100
What are the different types of melanoma?
1. Lentigo maligna (seen in the elderly, hands/face/neck, sun exposure, long radial growth phase)
2. Superficial spreading (seen on the trunk)
3. Acral lentiginous (seen on the hands, palms, and soles)
4. Nodular (increased vertical phase - goes deep fast)
Each has an in situ and an invasive phase
101
Which types of melanoma have a significant radial growth phase and why is this important?
LM, SS, AL - unlikely that it has metastasized (no vasculature in the epidermis)
102
Which types of melanoma have a significant vertical growth phase?
Nodular and any type of invasive melanoma
103
What are the two most important predisposing risk factors for melanoma?
1. Sun exposure
| 2. Inherited genes
104
How does melanoma vary between men and women and between light skin and dark skin?
M: upper back vs. F: posterior legs
Light skin >> dark skin
105
What are some of the genes involved in melanoma?
1. CDKN2A - mutation that diminishes the activity of RB tumor suppressor proteins
2. Increase in RAS and PI3K/AKT signaling, which promote cell growth and survival
3. BRAF, NRAS, PTEN, C-KIT (study further if there is time)
106
What is the most common mutation in sporadic melanoma?
BRAF
107
What is the most common mutation in familial melanoma?
CDKN2A
108
What is the best prognostic feature for melanoma?
Breslow thickness
109
What are favorable prognostic factors for melanoma?
1. Depth <1.7 mm
2. No ulceration
3. No mitoses
4. Negative sentinel lymph nodes
5. Brisk TIL response
6. Absence of regression
7. Female gender
8. Location on extremity
110
How is melanoma staged?
Stage 0 - MIS
Stage 1/2 - confined to skin with any depth
Stage 3 - nodal involvement
Stage 4 - distant skin or visceral metastasis
111
Compare lentigo simplex, banal (ordinary nevus), dysplastic nevus, and melanoma with respect to the presence of melanocytes as single cells.
LS - yes
BN - yes
DN - yes
M - yes
112
Compare lentigo simplex, banal (ordinary nevus), dysplastic nevus, and melanoma with respect to the presence of melanocytes as nests.
LS - no
BN - yes
DN - yes
M - yes
113
Compare lentigo simplex, banal (ordinary nevus), dysplastic nevus, and melanoma with respect to the presence of shouldering, bridging, lamellar fibropasia, and cellular atypia.
LS - no
BN - no
DN - yes
M - yes
114
Compare lentigo simplex, banal (ordinary nevus), dysplastic nevus, and melanoma with respect to the presence of confluence and pagetoid spread.
LS - no
BN - no
DN - no
M - yes
115
List the dermal neoplasms arising from follicles.
1. Epidermal inclusion cysts (follicular cyst)
| 2. Trichilemmoma
116
List the dermal neoplasms arising from histiocytes.
1. Dermatofibroma
2. Keloid
3. Dermatofibroma sarcoma protuberans
117
List the dermal neoplasms arising from eccrine/aprocrine glands.
1. Cylindroma
118
List the dermal neoplasms arising from sebaceous glands.
1. Sebaceous adenoma
119
List the dermal neoplasms arising from vasculature.
1. Pyogenic granuloma
2. Bacillary angiomatosis
3. Cherry hemangioma
4. Cystic hygroma
5. Glomus tumor
6. Strawberry hemangioma
7. Kaposi sarcoma
8. Angiosarcoma
120
List the dermal neoplasms arising from smooth muscle.
1. Leiomyoma
121
How does an epidermal inclusion cyst appear grossly?
Nodule under the skin
122
How does an epidermal inclusion cyst appear on histology?
Epithelial-lined cyst with keratin debris and a granular layer lining the epithelium
123
How do trichilemmomas appear grossly?
Multiple flesh-colored papules, usually around the nose and mouth
124
What are trichilemmomas associated with?
PTEN mutations
| Cowden's syndrome (AD) - increased risk for breast, endometrial, and thyroid cancers
125
How do trichilemmomas appear on histology?
Endophytic growth of ordinary clear cells
| Palisading and pushing border
126
How do dermatofibromas appear grossly?
Pink to brown papule or nodule most common on lower extremities, dimples when pushed together
127
How do dermatofibromas appear on histology?
1. Dermal proliferation of boomerang-shaped fibrohistiocytes
2. Collagen trapping**
3. Overlying tabling of rete ridges
4. Basal layer hyperpigmentation
128
How do dermatofibrosarcoma protuberans appear grossly?
Large nodule with multiple protuberances; most common on the trunk of young to middle-aged adults
129
How do dermatofibrosarcoma protuberans appear on histology?
1. Dense proliferation of spindle cells in the dermis
| 2. Storiform (irregulary whorled) pattern of fibroblasts
130
How does a keloid scar appear grossly?
Firm, smooth, hard growths
131
How does a keloid scar appear on histology?
1. Dermal proliferation of spindle cells
| 2. Fibroblasts and myofibroblasts with wide bands of collagen with large, brightly eosinophilic, glassy fibers
132
How does a cylindroma appear grossly?
Solitary or multiple small papules and/or large dome-shaped nodules on the scalp, face, or extremities (occasionally); "turban tumor"
133
How does a cylindroma appear on histology?
1. Non-encapsulated tumor nodule arising in the dermis formed by multiple irregular tumor islands (jigsaw pattern)
2. Thick hyaline deposit surrounds the tumor island; also seen in discrete droplets within the nodules
3. Two populations of cells: smaller cells with a hyperchromatic nucleus tending to the periphery, larger cells with open nuclei throughout the center of the nodule
134
How does a sebaceous adenoma appear grossly?
Yellowish papule or small nodule
135
What are sebaceous adenomas associated with?
Lynch Syndrome/Muir Torre syndrome (MLH1, MSH2, MSH6), especially if multiple or cystic
136
How does a sebaceous adenoma appear on histology?
Relatively well-circumscribed lobulated tumor consisting of lobules of sebaceous cells (bubbly cytoplasm) lined by basaloid cells
137
How do pyogenic granulomas appear grossly?
Single papules that are ulcerated (upper extremities, especially fingers)
138
How do pyogenic granulomas appear on histology?
Lobular capillary proliferation, mixed inflammatory infiltrate, often ulcerated and crushed
139
How does bacillary angiomatosis appear grossly?
Single or multiple papules
140
What causes bacillary angiomatosis and what is it associated with?
Caused by infection Bartonella Henselae; associated with AIDs
141
How does bacillary angiomatosis appear on histology?
Resembles PG and KS, but has neutrophils and positive staining with Warthin Starry
142
How does a cherry hemangioma appear grossly and on histology?
Single or multiple papules; benign proliferation of capillaries (frequency increases with age)
143
How does a strawberry hemangioma appear grossly and on histology?
Benign proliferation of capillaries appearing in the first few weeks of life, regresses by age 5-8; histology same as cherry angioma
144
How does a cystic hygroma appear grossly?
Cavenous lymphangioma of the neck
145
What is cystic hygroma associated with?
Turner syndrome (female partly or completely missing an X-chromosome, presentation: short, webbed neck, low-set ears, low hairline, short stature, swollen hands and feet at birth)
146
How does a glomus tumor appear grossly?
Benign, painful red-blue tumor commonly under the fingernails
147
Glomus tumors arise from ___ cells of the ___ body.
Smooth muscle; thermoregulatory glomus
148
Compare PG/hemangioma to GT.
PG/hemangioma: more vessels than cells
GT: more cells than vessels
149
What is a kaposi sarcoma?
Malignant vascular tumor of the skin, mouth, GI tract, respiratory system; common on the feet
150
What is kaposi sarcoma associated with?
HHV-8 and HIV
151
How does kaposi sarcoma appear on histology?
Lymphocytic infiltrate, proliferation of spindle cells, extravasated blood cells; HHV8+ stain
152
What is an angiosarcoma?
Malignant vascular tumor in the head, neck, and breast areas occurring in the elderly, sun-exposed, radiation, lymphedema
153
Hepatic angiosarcoma is associated with exposure to what substances?
Vinyl chloride and arsenic
154
COMPLETE TABLE - SLIDE 75
Do it.
155
How does a pilar type leiomyoma appear on histology?
Small fascicles of bland, eosinophilic spindle cells in the mid-dermis; cigar-shaped nuclei, bubbles
156
How doe a pilar type leiomyoma appear grossly?
Flesh-colored nodule of the skin
157
List the patterns of inflammatory dermatosis.
1. Lichenoid
2. Psoriasiform
3. Spongiotic
4. Bullous
158
Describe lichenoid dermatitis.
Band of inflammation at the DEJ
159
List the types of lichenoid dermatitis.
1. Lichen planus
2. Erythema multiforme
3. SJS/TENS
4. Cutaneous T cell lymphoma (mycosis fungoides)
160
What are the 5 P's of lichen planus?
Pruritic, purple, polygonol, papules, plaques (also Wickham striae, common oral involvement)
161
How does lichen planus appear on histology?
1. Lichenoid lymphocytic infiltrate with epidermal hyperplasia, hypergranulosis
2. Sawtooth rete ridges
3. Colloid bodies (CD) - dead keratinocytes - on the basal layer
162
How does EM, SJS, and TEN appear on histology?
Lichenoid dermatitis with necrotic keratinocytes (Civatte bodies), prominent or confluent (full thickness - not just the basal layer)
163
What causes EM?
Infections, most commonly HSV; self-resolving
164
What causes SJS/TENs?
Drug-induced
165
What defines SJS/TENS?
Mucosal involvement, body surface involvement >30%
166
How does EM appear grossly?
Characteristic target
167
How does EM appear on histology?
More sparse lichenoid infiltrate, plentiful necrotic keratinocytes high in the epidermis
168
How does TEN appear on histology?
Necrotic keratinocytes at all levels of epidermis (full thickness necrosis); no epidermis
169
How does cutaneous T cell lymphoma appear grossly?
Patches/plaques on the trunk (older people)
170
How does cutaneous T cell lymphoma appear on histology?
1. Atypical lymphocytes along the DEJ (look like soldiers); band-like pattern
2. Pautrier's microabscess (collection of atypicaly lymphocytes within the dermis)
3. Cerebriform nuclei
171
Describe psoriasiform dermatitis.
Regular acanthosis (thickening of the epidermis)
172
What is psoriasis associated with?
Arthritis, myopathy, enteropathy, spondylitic joint disease, acquired immunodeficiency
173
What are genetic and environmental factors of psoriasis?
2/3 affected have HLA-C, but only 10% of HLA-C people have psoriasis
CD4+ and CD8+ cells accumulate, Ag unknown
174
How does psoriasis appear grossly?
1. Well-demarcated plaques with adherent silver/white scales
| 2. 30% have nail changes - yellow-brown discoloration with pitting, onycholysis (splitting apart)
175
Where is psoriasis found on the body?
Elbows, kness, scalp, lumbosacral, intergluteal cleft, glans penis
176
How does psoriasis appear on histology?
1. Psoriasiform hyperplasia with parakeratotic "wafer-like" scales containing neutrophils
2. Acanthosis
3. Munroe microabscesses (filled with neutrophils)
4. Spongiform pustules in the epidermis
5. Thinning of the suprapapillary plates with dilated papillary vessels (Auspitz sign)
6. Loss of granular layer, increased epidermal mitotic figures
177
Describe spongiotic dermatitis.
Irregular acanthosis with edema in the epidermis
178
What is a common form of spongiotic dermatitis?
Eczema
179
What is seen on histology in eczema?
Irregular acanthosis, vesicle formation, eosinophils
180
What is allergic contact dermatitis?
Inflammatory disorder initiated by contact with an allergen to which the person has been previously sensitized
181
How does allergic contact dermatitis appear grossly?
Erythematous papules, small vesicles, or weeping plaques, very pruritic, glove-like distribution; occurs 12-48 hours after exposure to allergen (delayed hypersensitivity rxn)
182
Describe bullous dermatitis.
Vesicles or bullae caused by splits in the epidermis or by the DEJ
183
List the types of bullous dermatitis.
1. Bullous pemphigoid
2. Pemphigus vulgaris
3. Dermatitis herpetiformis
184
How is bullous dermatitis diagnosed?
Direct IF
185
Diagnosis of bullous dermatitis depends on what three features?
1. Anatomic level of split
2. Underlying mechanism of the split
3. Nature of the inflammatory infiltrate
186
Discuss the features of bullous pemphigoid.
1. Occurs in older individuals
2. Tense bullae on the inner aspects of thighs, flexor surfaces of forearms, axillae, groin, and lower abdomen
3. Subepidermal blister with eosinophils
4. IgG Ab to hemidesomsomes - linear pattern at the BM
5. Split is at the DEJ
Ag - BPAG1 and 2
187
Discuss the features of pemphigus vulgaris.
1. Superficial vesicles and bullae that rupture easily, leaving shallow, crusted erosions
2. Acanthloysis results in suprabasilar clefting (tombstoning)
3. Dissolution due to IgG Ab against desmoglein
4. Net-like IgG and C3 on direct immunoflorescence
5. Suprabasilar split
188
Discuss the features of dermatitis herpetiformis.
1. Pruritic papules/vesicles on erythematous base (elbows, buttocks)
2. Associated with celiac (Ab to gliadin)
3. Granular IgA deposits on direct immunofluorescence
4. DEJ split
5. Neutrophils
189
What causes verruca?
HPV
190
What are the different types of verruca?
1. Verruca vulgaris - common type (warts)
2. Verruca plana - face and dorsal hands
3. Verruca plantaris/palmaris
4. Condyloma acuminatum (HPV 6, 11)
191
How does verruca vulgaris appear on histology?
1. Hyperkeratosis
2. Hypergranulosis (dark purple)
3. Papillomatosis
4. Koilocytes - vacuolated keratinocytes with raisin-like nuclei
192
How does molluscum contagiosum appear on histology?
1. Crater produced by epidermal hyperplasia
2. Henderson-Patterson (molluscum) bodies in the crater - intracytoplasm inclusions that push the nucleus and keratohyaline granules aside
Very common in childhood
193
Compare HSV 1 and 2 with Varicella Zoster virus (VZV)
1. Both part of human herpes virus family
2. Both double stranded DNA virus with similar mechanisms for infection
3. Both have the ability to cause primary and latent infection
4. Both cause a vesicular viral exanthem (maculopapular rash with vesicles on top)
5. Positive Tzanck or DFA of blister contents, positive viral culture
194
The first infection with HSV1/2 is often asymptomatic. How do primary or latent infections present?
Vesicles or erosions
195
HSV1 more commonly causes infection in what location? HSV2?
Oral - more commonly HSV1
| Genital - more commonly HSV2
196
What are the 3 M's of HSV?
Molding, multinucleated, marginated chromatin
197
What is a primary VZV infection and how does it present?
Chicken pox; vesicles on a red base/papules/crusted erosion; transmitted by respiratory secretions and cutaneous lesions
198
What is a reactivation of VZV infection and how does it present?
Shingles; focal unilateral/dermatomal distribution (unless disseminated); painful/pruritic vesicles most commonly on the trunk; increased in patients over 50 or in people who are immunocompromised
199
What is the Hutchinson sign?
HSV involvement of the nose, which alerts the physician to the possibility of ocular involvement (which can lead to vision impairment)
200
What causes bullous impetigo?
Most common - Staph
Also GAS
Specifically exfoliative toxicns A and B from Phage II Group 71 Staph attack the epidermis, resulting in subcorneal splitting
201
Bullous impetigo is most common in ___ - how does it present?
Children; flaccid blisters that collapse easily resulting in honey-colored crust
202
How is bullous impetigo treated?
MRSA mupirocin
203
How does bullous impetigo appear on histology?
Subcorneal blister with neutrophils +/- bacteria
204
What causes scalded skin syndrome?
Exotoxin from S. Aureus destroys keratinocyte desmosomes, leading to fever and generalized erythematous rash with sloughing of the upper layers of the epidermis
Seen in newborns, children, and adults with renal insufficiency
205
Compare TENS, BI, and SSSS with respect to site of epidermal split.
TENS - DEJ
BI - Sub-epidermis
SSSS - Sub-epidermis
206
Compare TENS, BI, and SSSS with respect to organisms present.
TENS - no
BI - yes
SSSS - no
207
Compare TENS, BI, and SSSS with respect to systemic symptoms.
TENS - yes
BI - no
SSSS - yes
208
Compare TENS, BI, and SSSS with respect to culture.
TENS - n/a
BI - yes (skin)
SSSS - yes (not skin)
209
What is erysipelas?
Infection involving the superficial dermis and lymphatics caused by S. pyogenes; well-defined demarcation between infected and normal skin; dermal edema
210
What is cellulitis?
Acute, painful spreading infection of deeper dermis and subcutaneous tissue caused by S. pyogenes or S. Aureus; starts with break from trauma or other infection
211
What is necrotizing fasciitis?
Infection involving deep subcutaneous tissue/fascia caused by S. pyogenes; crepitus, pain out of proportion to clinical findings
212
What are dermatophytes and what are the most common genera?
Fungus that live on keratin; Microsporum, Trichophyton, Epidermophyton
213
How do are dermatophytes imaged in the lab?
Hyphae on KOH prep, in corneal layer using PAS stain
214
What are the 4 types of dermatophyte infections?
1. Tinea pedis - foot
2. Tinea corpora - body
3. Tinea cruris - inguinal folds
4. Tinea capitis - scalp
215
What is onychomycosis?
Dermatophyte infection of the nail
216
How does tinea versicolor appear grossly?
Macules and patches of hypo/hyperpigmentation on the trunk
217
How does tinea versicolor appear on histology?
Spaghetti and meatball appearance of hyphae and yeast forms (Malassezia globosa organisms) - can visualize with Wood's lamp as well
218
How does tinea nigra appear grossly?
Tan-brown patches on palms or soles
219
What causes scabies?
Sarcoptes scabiei mite; overcrowding, poor hygiene, sexual contact
220
How does scabies appear grossly?
Papulovesicular, persistent nodules, Norwegian (crusted forms), often seen in webbed spaces between fingers
221
How does cutaneous infection with blastomycosis appear histologically?
1. Epidermal acanthosis
2. Dermal necrosis
3. Histiocytes
Broad based budding yeast form
222
How does cutaneous infection with coccidiomycosis appear histologically?
Large spherule with little spherules inside (bigger than blast)
223
How does cutaneous infection with cryptococcus neoformans appear grossly and histologically?
Gross - nodules with central area of umbilication
Histology - large, intracellular or free yeast-like organisms, mucin stains thick capsule; very small
224
How does cutaneous infection with histoplasm capsulatum appear histologically?
Very small intracytoplasmic organisms with surroudning clear halo, PAS and GMS +, often within histiocytes
